# Model Operations¶

The model operations configure the entity-relationship model that will be used to structure tabular data in the ERMrest catalog. The model must be configured before use, but it may continue to be adjusted throughout the lifecycle of the catalog, interleaved with data operations.

## Schemata Retrieval¶

The GET operation is used to retrieve a document describing the entire catalog data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema
• service /catalog/ cid [ @ revision ] /schema/

In this operation, content-negotiation SHOULD be used to select the application/json representation as other content types MAY be returned, including HTML-based user interfaces:

GET /ermrest/catalog/42/schema HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

{
"schemas": {
schema name: schema representation, ...
}
}


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is a single field schemas which in turn is a sub-object used as a dictionary mapping. Each field name of the sub-object is a schema name and its corresponding value is a schema representation as described in Schema Retrieval.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Bulk Schemata and Table Creation¶

The POST operation can be used to create multiple named schemata and/or tables in a single request by posting a complex JSON document to the same resource used for retrieving all schemata:

• service /catalog/ cid /schema

In this operation, application/json content MUST be provided. The same format returned in schemata retrieval is supported:

POST /ermrest/catalog/42/schema HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"schemas": {
schema name: schema representation, ...
}
}


with this form, each schema name MUST be distinct and available for use as a new schema in the catalog. Each schema representation MAY include multiple fields as described in the Schema Retrieval documentation. If present, the "schema_name" field MUST match the schema name key of the enclosing document. If present, the "tables" field MAY describe new tables which will also be created as part of the same request.

Optionally, a batch request list document is also supported:

POST /ermrest/catalog/42/schema HTTP/1.1
Host: www.example.com
Content-Type: application/json

[
schema, table, or foreign-key representation, ...
]


In this form, each schema representation, table representation, or foreign key representation is handled similarly to the Schema Creation, Table Creation, or Foreign Key Creation APIs, respectively. The list of representations are processed in document order, and embedded sub-resources are also created. With both forms, a set of tables with interdependent foreign key constraints MAY be specified and the service will defer all foreign key definitions until after all tables and keys have been defined.

On success, the response is:

HTTP/1.1 201 Created
Content-Type: application/json

...new resource representation...


Typical error response codes include:

• 403 Forbidden
• 409 Conflict
• 401 Unauthorized

The request effects are atomic, either applying all elements of the batch change to the catalog model or making no changes at all in the case of failures.

## Schema Creation¶

The POST operation is used to create new, empty schemata, using a model-level resource name of the form:

• service /catalog/ cid /schema/ schema name

In this operation, no input is required:

POST /ermrest/catalog/42/schema/schema_name HTTP/1.1
Host: www.example.com


On success, the response is:

HTTP/1.1 201 Created


BUG: should be 204 No Content and/or should include Location header for new schema?

Typical error response codes include:

• 409 Conflict
• 403 Forbidden
• 401 Unauthorized

## Schema Retrieval¶

The GET operation is used to retrieve a document describing the one schema in the data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

{
"schema_name": schema name,
"comment": comment,
"annotations": {
annotation key: annotation document, ...
}
"tables": {
table name: table representation, ...
}
}


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is a single object with the following fields:

• schema_name: whose value is the schema name addressed in the retrieval request
• comment: whose value is a human-readable comment for the schema
• annotations: whose value is a sub-object use as a dictionary where each field of the sub-object is an annotation key and its corresponding value a nested object structure representing the annotation document content (as hierarchical content, not as a double-serialized JSON string!)
• tables: which is a sub-object used as a dictionary mapping. Each field name of the sub-object is a table name and its corresponding value is a table representation as described in Table Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Schema Alteration¶

The PUT operation is used to alter an existing schema’s definition:

• service /catalog/ cid /schema/ schema name

In this operation, the application/json schema representation is supplied as input:

PUT /ermrest/catalog/42/schema/schema_name HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"schema_name": new schema name,
"comment": new column comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input schema representation is as for schema creation via the POST request. Instead of creating a new schema, the existing schema with schema name as specified in the URL is altered to match the input representation. Each of these fields, if present, will be processed as a target configuration for that aspect of the table definition:

• schema_name: a new schema name to support renaming from schema name to new schema name
• comment: a new comment string
• annotations: a replacement annotation map
• acls: a replacement ACL set

Other schema fields are immutable through this interface, and such input fields will be ignored.

Absence of a named field indicates that the existing state for that aspect of the definition should be retained without change. For example, an input to rename a schema and set a comment would look like:

{
"schema_name": "the new name",
"comment": "This is my new named table."
}


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

schema representation


where the body content represents the schema status at the end of the request.

NOTE: In the case that the schema name is changed, the returned document will indicate the new name, and subsequent access to the model resource will require using the updated URL:

• service /catalog/ cid [ @ revision ] /schema/ new schema name

The old URL will immediately start responding with a schema not found error.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Schema Deletion¶

The DELETE method is used to delete a schema:

DELETE /ermrest/catalog/42/schema/schema_name HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Table List Retrieval¶

The GET operation is used to retrieve a list of tables in one schema using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/

In this operation, content-negotiation SHOULD be used to select the application/json representation as other content types MAY be returned, including HTML-based user interfaces:

GET /ermrest/catalog/42/schema/schema_name/table HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

[
table representation, ...
]


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is an array where each element is a table representation as described in Table Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Table Creation¶

The POST operation is used to add a table to an existing schema’s table list resource:

• service /catalog/ cid /schema/ schema name /table
• service /catalog/ cid /schema/ schema name /table/

In this operation, the application/json table representation is supplied as input:

POST /ermrest/catalog/42/schema/schema_name/table HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"schema_name": schema name,
"table_name": table name,
"comment": table comment,
"annotations": {
annotation key: annotation document, ...
},
"column_definitions": [ column representation, ... ],
"keys": [ key representation, ... ],
"foreign_keys": [ foreign key representation, ... ],
"kind": "table"
}


The input table representation is a long JSON document too verbose to show verbatim in this documentation. Its general structure is a single object with the following fields:

• schema_name: whose value is the same schema name addressed in the request URL (optional content in this request)
• table_name: whose value is the table name string for the new table
• comment: whose value is the human-readable comment string for the new table
• annotations: whose value is a sub-object use as a dictionary where each field of the sub-object is an annotation key and its corresponding value a nested object structure representing the annotation document content (as hierarchical content, not as a double-serialized JSON string!)
• column_definitions: an array of column representation as described in Column Creation, interpreted as an ordered list of columns
• keys: an array of key representation as described in Key Creation, interpreted as an unordered set of keys
• foreign_keys: an array of foreign key representation as described in Foreign Key Creation, interpreted as an unordered set of foreign keys
• kind: a string indicating the kind of table
• normally table for a regular mutable table
• the value view MAY be encountered when introspecting existing ERMrest catalogs which may have extended data models not created through the standard ERMrest model management interface; the view kind of table supports data retrieval operations but does not support data creation, update, nor deletion;
• this mechanism MAY be used for future extension so other values SHOULD be detected and the enclosing table representation ignored if a client does not know how to interpret that table kind.

On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

table representation


where the body content is the same table representation as the request input content, representing the table as created. This response MAY differ from the input content. It is RECOMMENDED that the service generate a newly serialized representation of the newly created table, and this result MAY differ from the request input.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized
• 409 Conflict

## Table Retrieval¶

The GET operation is used to retrieve a document describing one table in the data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

table representation


The response body is a table representation as described in Table Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized
• 409 Conflict

## Table Alteration¶

The PUT operation is used to alter an existing table’s definition:

• service /catalog/ cid /schema/ schema name /table/ table name

In this operation, the application/json table representation is supplied as input:

PUT /ermrest/catalog/42/schema/schema_name/table/table_name HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"schema_name": destination schema name,
"table_name": new table name,
"comment": new column comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input table representation is as for table creation via the POST request. Instead of creating a new table, the existing table with table name as specified in the URL is altered to match the input representation. Each of these fields, if present, will be processed as a target configuration for that aspect of the table definition:

• schema_name: an existing schema name to support moving from schema name to destination schema name
• table_name: a new name to support renaming from table name to new table name
• comment: a new comment string
• annotations: a replacement annotation map
• acls: a replacement ACL set
• acl_bindings: a replacement ACL bindings set

Other table fields are immutable through this interface, and such input fields will be ignored.

Absence of a named field indicates that the existing state for that aspect of the definition should be retained without change. For example, an input to rename a table and set a comment would look like:

{
"table_name": "the new name",
"comment": "This is my new named table."
}


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

table representation


where the body content represents the table status at the end of the request.

NOTE: In the case that the table name is changed or the table is relocated to a different schema, the returned document will indicate the new names, and subsequent access to the model resource will require using the updated URL:

• service /catalog/ cid [ @ revision ] /schema/ new schema name /table/ new table name

The old URL will immediately start responding with a table not found error.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Table Deletion¶

The DELETE method is used to delete a table and all its content:

DELETE /ermrest/catalog/42/schema/schema_name/table/table_name HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized
• 409 Conflict

## Column List Retrieval¶

The GET operation is used to retrieve a list of columns in one table using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/column HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

[
column representation, ...
]


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is an array where each element is a column representation as described in Column Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Column Creation¶

The POST operation is used to add a column to an existing table’s column list resource:

• service /catalog/ cid /schema/ schema name /table/ table name /column
• service /catalog/ cid /schema/ schema name /table/ table name /column/

In this operation, the application/json column representation is supplied as input:

POST /ermrest/catalog/42/schema/schema_name/table/table_name/column HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"name": column name,
"type": column type,
"default": default value,
"nullok": boolean,
"comment": column comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input column representation is a long JSON document too verbose to show verbatim in this documentation. Its general structure is a single object with the following fields:

• name: whose value is the column name string for the new column which must be distinct from all existing columns in the table
• type: whose value is the column type drawn from a limited set of supported types in ERMrest
• default: whose value is an appropriate default value consistent with the column type or the JSON null value to indicate that NULL values should be used (the default when default is omitted from the column representation)
• nullok: JSON true if NULL values are allowed or false if NULL values are disallowed in this column (default true if this field is absent in the input column representation)
• comment: whose value is the human-readable comment string for the column
• annotations: whose value is a sub-object use as a dictionary where each field of the sub-object is an annotation key and its corresponding value a nested object structure representing the annotation document content (as hierarchical content, not as a double-serialized JSON string!)
• acls: whose value is a sub-object specifying ACLs for the new column
• acl_bindings: whose value is a sub-object specifying ACL bindings for the new column

On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

column representation


where the body content is the same column representation as the request input content, representing the column as created. This response MAY differ from the input content. It is RECOMMENDED that the service generate a newly serialized representation of the newly created column, and this result MAY differ from the request input.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Column Indexing Preferences¶

During column creation, whether as modification to an existing table or as part of new table creation, a special annotation tag:isrd.isi.edu,2018:indexing-preferences MAY be used to supply hints which override implicit service behavior for constructing column indexes in the underlying database. *These hints are only effective if available during column creation; they have no effect if applied to a column after it already exists in the catalog.

The indexing-preferences annotation can be applied at multiple levels of the catalog’s model resource hierarchy, but only has an effect when interpreted with respect to a specific column. The purpose of annotations at other levels are to override default hints to apply in the absence of an indexing-preferences annotation on a specific column:

1. Catalog-level annotation to set default hints for columns created in all tables in that catalog;
2. Schema-level annotation to set default hints for columns created in tables in that schema;
3. Table-level annotation to set default hints for columns created in that table;
4. Column-level annotation to set hints for that column.

Furthermore, the default hints are searched from most specific to least specific model level on a key-by-key basis. Thus, the effective hints for a given column can be a blend of hints supplied at various levels if those hints are sparsely populated rather than fully specifying every sub-field within the annotation.

Example annotation payload to suppress unnecessary btree indexes and GIN tri-gram indexes:

"annotations": {
"tag:isrd.isi.edu,2018:indexing-preferences": {
"btree": false,
"trgm": false
}
}


This could be applied to minimize index maintenance and storage costs on a catalog where search is limited or insensitive to query performance. The service will still create indexes necessary for correct function, such as btree indexes used to enforce key uniqueness and foreign key referential integrity constraints.

Example annotation payload to suppress unnecessary btree indexes but enable built-in GIN tri-gram indexes which are used to accelerate regular-expression matching:

"annotations": {
"tag:isrd.isi.edu,2018:indexing-preferences": {
"btree": false,
"trgm": true
}
}


Example annotation payload to enable a custom btree index and to disable the built-in GIN tri-gram index for a specific column:

"annotations": {
"tag:isrd.isi.edu,2018:indexing-preferences": {
"btree": [ "column1", "column2" ],
"trgm": false
}
}


In practice, this would only be sensible as a column-level annotation on the column named column1 where it is desired to accelerate search, sort, or joins not just by column1 but by the ordered pair (column1, column2).

Example annotation payload to suppress the btree index and enable GIN tri-gram and GIN array indexing for an array-typed column:

"annotations": {
"tag:isrd.isi.edu,2018:indexing-preferences": {
"btree": false,
"trgm": true,
"gin_array": true
}
}


In practice, this would be sensible as a column-level annotation where you want to accelerate = equality filter predicates as well as ::regexp::/::ciregexp:: regular-expression predicates on a column storing arrays of values.

## Column Retrieval¶

The GET operation is used to retrieve a document describing one column in the data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ column name

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/column/column_name HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

column representation


The response body is a column representation as described in Column Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Column Alteration¶

The PUT operation is used to alter an existing column’s definition:

• service /catalog/ cid /schema/ schema name /table/ table name /column/ column name

In this operation, the application/json column representation is supplied as input:

PUT /ermrest/catalog/42/schema/schema_name/table/table_name/column/column_name HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"name": new column name,
"type": new column type,
"default": new default value,
"nullok": new boolean,
"comment": new column comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input column representation is as for column creation via the POST request. Instead of creating a new column, the existing column with column name as specified in the URL is altered to match the input representation. Each of these fields, if present, will be processed as a target configuration for that aspect of the column definition:

• name: a new name to support renaming from column name to new column name
• type: a new type to support changing from existing to new column type
• default: a new default value for future row insertions
• nullok: a new nullok status
• comment: a new comment string
• annotations: a replacement annotation map
• acls: a replacement ACL set
• acl_bindings: a replacement ACL bindings set

Absence of a named field indicates that the existing state for that aspect of the column definition should be retained without change. For example, an input to rename a column, disallow nulls, and set a new default value would look like:

{
"name": "the new name",
"nullok": false,
"default": "the new default value"
}


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

column representation


where the body content represents the column status at the end of the request.

NOTE: In the case that the column name is changed with the "name": new column name input syntax, the returned document will indicate the new name, and subsequent access to the model resource will require using the updated URL:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ new column name

The old URL will immediately start responding with a column not found error.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Column Deletion¶

The DELETE method is used to remove a column and all its content from a table:

DELETE /ermrest/catalog/42/schema/schema_name/table/table_name/column/column_name HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Key List Retrieval¶

The GET operation is used to retrieve a list of keys in one table using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /key
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /key/

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/key HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

[
key representation, ...
]


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is an array where each element is a key representation as described in Key Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Key Creation¶

The POST operation is used to add a key constraint to an existing table’s key list resource, or a pseudo-key constraint to a view’s key list resource:

• service /catalog/ cid /schema/ schema name /table/ table name /key
• service /catalog/ cid /schema/ schema name /table/ table name /key/

In this operation, the table name MAY be an existing table or view in the named schema, and the application/json key representation is supplied as input:

POST /ermrest/catalog/42/schema/schema_name/table/table_name/key HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"names": [
[ schema name, constraint name ], ...
],
"unique_columns": [ column name, ... ],
"comment": comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input key representation is a JSON document with one object with the following fields:

• names: an array of [ schema name , constraint name ] pairs representing names of underlying constraints that enforce this unique key reference pattern.
• unique_columns has an array value listing the individual columns that comprise the composite key. The constituent columns are listed by their basic column name strings.
• comment: whose value is the human-readable comment string for the key
• annotations: whose value is a sub-object use as a dictionary where each field of the sub-object is an annotation key and its corresponding value a nested object structure representing the annotation document content (as hierarchical content, not as a double-serialized JSON string!)

During key creation, the names field SHOULD have at most one name pair. Other names inputs MAY be ignored by the server. When the names field is omitted, the server MUST assign constraint names of its own choosing. In introspection, the names field represents the actual state of the database and MAY include generalities not controlled by the key creation API:

• ERMrest will refuse to create redundant constraints and SHOULD reject catalogs where such constraints have been defined out of band by the local DBA.
• The chosen schema name for a newly created constraint MAY differ from the one requested by the client.
• The server MAY create the constraint in the same schema as the constrained table
• Pseudo keys are qualified by a special schema name of "" which is not a valid SQL schema name.
• Pseudo keys MAY have an integer constraint name assigned by the server.

On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

key representation


where the body content is the same key representation as the request input content, representing the key as created. This response MAY differ from the input content. It is RECOMMENDED that the service generate a newly serialized representation of the newly created key, and this result MAY differ from the request input.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Key Retrieval¶

The GET operation is used to retrieve a document describing one key in the data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /key/ column name ,

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/key/column_name,... HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

key representation


The response body is a key representation as described in Key Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Key Alteration¶

The PUT operation is used to alter an existing key’s definition:

• service /catalog/ cid /schema/ schema name /table/ table name /key/ key columns

In this operation, the application/json key representation is supplied as input:

PUT /ermrest/catalog/42/schema/schema_name/table/table_name/key/key_columns HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"names": [ [ schema name, new constraint name ] ],
"comment": new comment,
"annotations": {
annotation key: annotation document, ...
}
}


The input key representation is as for key creation via the POST request. Instead of creating a new key, the existing key with key columns as specified in the URL is altered to match the input representation. Each of these fields, if present, will be processed as a target configuration for that aspect of the definition:

• names: the new constraint name, i.e. second field of first element of names list, is a replacement constraint name
• comment: a new comment string
• annotations: a replacement annotation map

Other key fields are immutable through this interface. The unique_columns field, if present, must match the key columns in the URL.

Absence of a named field indicates that the existing state for that aspect of the definition should be retained without change. For example, an input to rename a key and set a comment would look like:

{
"names": [ ["table schema name", "the new constraint name" ] ],
"comment": "This is my newly named key."
}


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

key representation


where the body content represents the key status at the end of the request.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Key Deletion¶

The DELETE method is used to remove a key constraint from a table or a pseudo-key constraint from a view:

DELETE /ermrest/catalog/42/schema/schema_name/table/table_name/key/column_name,... HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Foreign Key List Retrieval¶

The GET operation is used to retrieve a list of foreign key references in one table using a model-level resource name of the following forms:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,/reference
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/ table reference

These names differ in how many constraints are applied to filter the set of retrieved foreign key references:

1. The list is always constrained to foreign keys stored in schema name : table name
2. The list MAY be constrained by the composite foreign key column name list of its constituent keys, interpreted as a set of columns
3. The list MAY be constrained by the table reference of the table containing the composite key or keys referenced by the composite foreign key

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/foreignkey HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

[
foreign key reference representation, ...
]


Note, this JSON document is usually quite long and too verbose to show verbatim in this documentation. Its general structure is an array where each element is a foreign key reference representation as described in Foreign Key Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Foreign Key Creation¶

The POST operation is used to add a foreign key reference constraint or pseudo-constraint to an existing table’s or view’s foreign key list resource:

• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/

In this operation, the application/json foreign key reference representation is supplied as input:

POST /ermrest/catalog/42/schema/schema_name/table/table_name/foreignkey HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
"names": [
[ schema name, constraint name ], ...
]
"foreign_key_columns": [
{
"schema_name": schema name,
"table_name": table name,
"column_name": column name
}, ...
]
"referenced_columns": [
{
"schema_name": schema name,
"table_name": table name,
"column_name": column name
}
],
"comment": comment,
"annotations": {
annotation key: annotation document, ...
},
"on_delete": delete action,
"on_update": update action
}


The input foreign key reference representation is a long JSON document too verbose to show verbatim in this documentation. Its general structure is a single object with the following fields:

• names: an array of [ schema name , constraint name ] pairs representing names of underlying constraints that enforce this foreign key reference pattern. For legacy compatibility this is a list, but it will have at most one member.
• foreign_key_columns: an array of column reference objects comprising the composite foreign key, each consisting of a sub-object with the fields:
• schema_name: whose value is the same schema name addressed in the request URL (optional content in this request)
• table_name: whose value is the same table name addressed in the request URL (optional content in this request)
• column_name: whose value names the constituent column of the composite foreign key
• referenced_columns: an array of column reference objects comprising the referenced composite key, each consisting of a sub-object with the fields:
• schema_name: whose value names the schema in which the referenced table resides
• table_name: whose value names the referenced table
• column_name: whose value names the constituent column of the referenced key
• comment: whose value is the human-readable comment string for the foreign key reference constraint
• annotations: whose value is a sub-object used as a dictionary where each field field of the sub-object is an annotation key and its corresponding value a nested object structure representing the annotation document content (as hierarchical content, not as a double-serialized JSON string!)
• on_delete: whose delete action value describes what happens when the referenced entity is deleted:
• NO ACTION (default) or RESTRICT: the reference is unchanged and an integrity violation will block the change to the referenced table. The difference between these two actions is only evident to local SQL clients who ERMrest.
• CASCADE: the referencing entities will also be deleted along with the referenced entity.
• SET NULL: the referencing foreign key will be set to NULL when the referenced entity disappears.
• SET DEFAULT: the referencing foreign key will be set to column-level defaults when the referenced entity disappears.
• on_Update: whose update action value describes what happens when the referenced entity’s key is modified:
• NO ACTION (default) or RESTRICT: the reference is unchanged and an integrity violation will block the change to the referenced table. The difference between these two actions is only evident to local SQL clients who ERMrest.
• CASCADE: the referencing foreign key will be set to the new key value of the referenced entity.
• SET NULL: the referencing foreign key will be set to NULL when the referenced key value is changed.
• SET DEFAULT: the referencing foreign key will be set to column-level defaults when the referenced key value is changed.

During foreign key creation, the names field SHOULD have at most one name pair. Other names inputs MAY be ignored by the server. When the names field is omitted, the server MUST assign constraint names of its own choosing. In introspection, the names field represents the actual state of the database and MAY include generalities not controlled by the foreign key creation REST API:

• ERMrest will refuse to create redundant constraints and SHOULD reject catalogs where such constraints have been defined out of band by the local DBA.
• The chosen schema name for a newly created constraint MAY differ from the one requested by the client.
• The server MAY create the constraint in the same schema as the referencing table, regardless of client request.
• Pseudo foreign keys are qualified by a special schema name of "" which is not a valid SQL schema name.
• Pseudo foreign keys MAY have an integer constraint name assigned by the server.

The two column arrays MUST have the same length and the order is important in that the two composite keys are mapped to one another element-by-element, so the first column of the composite foreign key refers to the first column of the composite referenced key, etc. In the referenced_columns list, the schema name and table name values MUST be identical for all referenced columns. If both referencing and referenced table name refer to tables, a real constraint is created; if either referencing or referenced table name refer to a view, a pseudo-constraint is created instead.

On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

foreign key reference representation


where the body content is the same foreign key reference representation as the request input content, representing the constraint as created. This response MAY differ from the input content. It is RECOMMENDED that the service generate a newly serialized representation of the newly created constraint, and this result MAY differ from the request input.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Foreign Key Retrieval¶

The GET operation is used to retrieve a document describing one foreign key constraint in the data model using a model-level resource name of the form:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/ table reference / key column ,

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET /ermrest/catalog/42/schema/schema_name/table/table_name/foreignkey/column_name,.../reference/table-reference/key_column,... HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

foreign key reference representation


The response body is a foreign key reference representation as described in Foreign Key Creation.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Foreign Key Alteration¶

The PUT operation is used to alter an existing foreign key’s definition:

• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/ table reference / key column ,

In this operation, the application/json key representation is supplied as input:

PUT /ermrest/catalog/42/schema/schema_name/table/table_name/key/column_name,.../reference/table_referenace/key_column,... HTTP/1.1
Host: www.example.com
Content-Type: application/json

[
{
"names": [ [ schema name, new constraint name ] ],
"on_update": new update action,
"on_delete": new delete action,
"comment": new comment,
"annotations": {
annotation key: annotation document, ...
}
}
]


The input foreign key reference representation is as for key creation via the POST request. Instead of creating a new foreign key, the existing one as specified in the URL is altered to match the input representation. To be symmetric with foreign key retrieval, the input is a JSON array with one sub-document. Each of these object fields, if present, will be processed as a target configuration for that aspect of the definition:

• names: the new constraint name, i.e. second field of first element of names list, is a replacement constraint name
• on_update: the new update action, e.g. one of NO ACTION, RESTRICT, CASCADE, SET DEFAULT, SET NULL
• on_delete: the new delete action, e.g. one of NO ACTION, RESTRICT, CASCADE, SET DEFAULT, SET NULL
• comment: a new comment string
• acls: a replacement ACL configuration
• acl_bindings: a replacement ACL binding configuration
• annotations: a replacement annotation map

Other key fields are immutable through this interface.

Absence of a named field indicates that the existing state for that aspect of the definition should be retained without change. For example, an input to rename a constraint and set a comment would look like:

{
"names": [ ["table schema name", "the new constraint name" ] ],
"comment": "This is my newly named key."
}


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

foreign key reference representation


where the body content represents the foreign key status at the end of the request.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Foreign Key Deletion¶

The DELETE method is used to remove a foreign key constraint from a table using any of the foreign key list or foreign key resource name forms:

• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,/reference
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/ table reference
• service /catalog/ cid /schema/ schema name /table/ table name /foreignkey/ column name ,/reference/ table reference / key column ,

These names differ in how many constraints are applied to filter the set of retrieved foreign key references:

1. The list is always constrained to foreign keys stored in schema name : table name
2. The list MAY be constrained by the composite foreign key column name list of its constituent keys, interpreted as a set of columns
3. The list MAY be constrained by the table reference of the table containing the composite key or keys referenced by the composite foreign key
4. The list MAY be constrained by the composite referenced key key column list

This example uses a completely specified foreign key constraint name:

DELETE /ermrest/catalog/42/schema/schema_name/table/table_name/key/column_name,.../reference/table_reference/key_column,... HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


The effect is to delete all foreign key constraints from the table matching the resource name used in the request.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Annotations¶

Annotations are generic sub-resources available within multiple subject resources. The possible subject resources are:

• service /catalog/ cid [ @ revision ]
• service /catalog/ cid [ @ revision ] /schema/ schema name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ column name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /key/ column name ,
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,

And the annotation sub-resources are named by appending /annotation/ to the subject resource as described in the following operations.

### Annotation List Retrieval¶

The GET operation is used to retrieve a document describing a set of annotations on one subject resource:

• subject /annotation/

For annotation retrieval, the optional @ revision qualifier is allowed on the cid of the subject.

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET subject/annotation/ HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

{
annotation key: annotation document, ...
}


Its general structure is a single object containing the annotations dictionary from the enclosing subject resource. Each field of the object is an annotation key and its corresponding value is the nested annotation document content.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Annotation Creation¶

The PUT operation is used to add or replace a single annotation:

• subject /annotation/ annotation key

For annotation creation, the @ revision qualifier is not allowed on the cid of the subject.

In this operation, the application/json annotation document is supplied as input:

PUT subject/annotation/annotation_key HTTP/1.1
Host: www.example.com
Content-Type: application/json

annotation document


The input annotation document is a arbitrary JSON payload appropriate to the chosen annotation key.

On success, the response is:

HTTP/1.1 201 Created


or:

HTTP/1.1 200 OK


without any response body. The 200 response indicates the annotation document replaces a previous one, while 201 responses indicate that a new annotation key has been added to the parent resource.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Annotation Bulk Update¶

The PUT operation can also replace the whole annotation list at once:

• subject /annotation

For annotation bulk update, the @ revision qualifier is not allowed on the cid of the subject.

In this operation, the application/json annotation list is supplied as input to specify all annotation key and annotation document values at once:

PUT subject/annotation HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
annotation key: annotation document, ...
}


This operation completely replaces any existing annotations, including dropping any which were present under an annotation key not specified in the bulk input list. This is most useful to an administrator who is intentionally clearing stale annotation content.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Annotation Retrieval¶

The GET operation is used to retrieve a document describing one annotation using a model-level resource name of the form:

• subject /annotation/ annotation key

For annotation retrieval, the optional @ revision qualifier is allowed on the cid of the subject.

In this operation, content-negotiation SHOULD be used to select the application/json representation:

GET subject/annotation/annotation_key HTTP/1.1
Host: www.example.com
Accept: application/json


On success, the response is:

HTTP/1.1 200 OK
Content-Type: application/json

annotation document


Its general structure is a single object containing annotation document content associated with annotation key.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Annotation Deletion¶

The DELETE method is used to delete an annotation using a model-level resource name of the form:

• subject /annotation/ annotation key

For annotation deletion, the @ revision qualifier is not allowed on the cid of the subject.

The request does not require content-negotiation since there is no response representation:

DELETE subject/annotation/annotation_key HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

Comments are generic sub-resources available within multiple subject resources. The possible subject resources are:

• service /catalog/ cid [ @ revision ] /schema/ schema name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ column name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /key/ column name ,
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,

And the comment sub-resources are named by appending /comment to the subject resource as described in the following operations.

### Comment Creation¶

The PUT operation is used to add or replace a single comment:

• subject /comment
• subject /comment/

For comment creation, the optional @ revision qualifier is not allowed on the cid of the subject.

In this operation, the text/plain comment text is supplied as input:

POST subject/comment/ HTTP/1.1
Host: www.example.com
Content-Type: text/plain

comment text


The input comment text is a arbitrary UTF-8 text payload.

On success, the response is:

HTTP/1.1 200 OK


without any response body.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Comment Retrieval¶

The GET operation is used to retrieve a document describing one comment using a model-level resource name of the form:

• subject /comment

For comment retrieval, the optional @ revision qualifier is allowed on the cid of the subject.

In this operation, content-negotiation is not necessary:

GET subject/comment HTTP/1.1
Host: www.example.com


On success, the response is:

HTTP/1.1 200 OK
Content-Type: text/plain

comment text


Its general structure is raw comment text.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Comment Deletion¶

The DELETE method is used to delete an comment using a model-level resource name of the form:

• subject /comment

For comment deletion, the optional @ revision qualifier is not allowed on the cid of the subject.

The request does not require content-negotiation since there is no response representation:

DELETE subject/comment HTTP/1.1
Host: www.example.com


On success, this request yields a description:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Access Control Lists¶

Access control lists (ACLs) are generic sub-resources available within multiple subject resources. The possible subject resources are:

• service /catalog/ cid [ @ revision ]
• service /catalog/ cid [ @ revision ] /schema/ schema name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ column name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,

And the ACL sub-resources are named by appending /acl to the subject resource as described in the following operations.

### Access Control Lists Retrieval¶

The GET method is used to get a summary of all access control (ACL) lists:

GET subject/acl HTTP/1.1
Host: www.example.com


On success, this request yields the ACL content as an object with one value list for each named ACL:

HTTP/1.1 200 OK
Content-Type: application/json

{
"owner": ["user1", "group2"],
"select": ["*"],
"update": [],
"delete": [],
"insert": [],
"enumerate": []
}


White-space is added above for readability. This legacy representation is likely to change in future revisions.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Bulk Access Control List Update¶

The PUT method can be used to reconfigure all access control lists on a single subject resource at once:

PUT subject/acl HTTP/1.1
Content-Type: application/json

{
"owner": ["user1", "group2"],
"select": ["*"],
"update": [],
"delete": [],
"insert": [],
"enumerate": []
}


The previous configuration of the subject access control lists is completely replaced. When subject is a whole catalog, absent ACL names are interpreted as implicitly present with value []. When subject is any other mode sub-resource, absent ACL names are interpreted as implicitly present with the value null.

On success, this request produces no content:

204 No Content


### Access Control List Creation¶

The PUT method is used to set the state of a specific access control list (the owner ACL in this example):

PUT subject/acl/owner HTTP/1.1
Content-Type: application/json

["user1", "group2"]


On success, this request produces no content:

204 No Content


### Access Control List Retrieval¶

The GET method is used to get the state of a specific access control list (the owner ACL in this example):

GET subject/acl/owner HTTP/1.1
Host: www.example.com


On success, this request yields the ACL content as a value list:

HTTP/1.1 200 OK
Content-Type: application/json

["user1", "group2"]


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Access Control List Deletion¶

The DELETE method is used to delete an access control list (the owner ACL in this example):

DELETE subject/acl/owner HTTP/1.1
Host: www.example.com


On success, this request yields an empty response:

HTTP/1.1 204 No Content


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

## Access Control List Bindings¶

Access control list bindings (ACL bindings) are generic sub-resources available within multiple subject resources. The possible subject resources are:

• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /column/ column name
• service /catalog/ cid [ @ revision ] /schema/ schema name /table/ table name /foreignkey/ column name ,

And the ACL binding sub-resources are named by appending /acl_binding to the subject resource as described in the following operations.

### Access Control List Bindings Retrieval¶

The GET method is used to get a summary of all access control list bindings:

GET subject/acl_binding HTTP/1.1
Host: www.example.com


On success, this request yields the ACL content as an object with one value list for each named ACL:

HTTP/1.1 200 OK
Content-Type: application/json

{
"my_example_binding": {
"types": ["owner"],
"projection": "My Owner Column",
"projection_type": "acl"
},
"my_example_binding2": {
"types": ["select"],
"projection": [{"filter": "Is Public", "operand": true}, "Is Public"],
"projection_type": "nonnull"
}
}


White-space is added above for readability. This legacy representation is likely to change in future revisions.

Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Bulk Access Control List Binding Update¶

The PUT method can be used to reconfigure all access control list bindings on a single subject resource at once:

PUT subject/acl HTTP/1.1
Content-Type: application/json

{
"my_example_binding": {
"types": ["owner"],
"projection": "My Owner Column",
"projection_type": "acl"
},
"my_example_binding2": {
"types": ["select"],
"projection": [{"filter": "Is Public", "operand": true}, "Is Public"],
"projection_type": "nonnull"
}
}


The previous configuration of access control list bindings on subject is completely replaced.

On success, this request produces no content:

204 No Content


### Access Control List Binding Creation¶

The PUT method is used to set the state of a specific access control list binding:

PUT subject/acl_binding/my_example_binding HTTP/1.1
Content-Type: application/json

{
"types": ["owner"],
"projection": "My Owner Column",
"projection_type": "acl"
}


On success, this request produces no content:

204 No Content


### Access Control List Binding Retrieval¶

The GET method is used to get the state of a specific access control list binding:

GET subject/acl_binding/my_example_binding HTTP/1.1
Host: www.example.com


On success, this request yields the ACL content as a value list:

HTTP/1.1 200 OK
Content-Type: application/json

{
"types": ["owner"],
"projection": "My Owner Column",
"projection_type": "acl"
}


Typical error response codes include:

• 403 Forbidden
• 401 Unauthorized

### Access Control List Binding Deletion¶

The DELETE method is used to delete an access control list binding:

DELETE subject/acl_binding/my_example_binding HTTP/1.1
Host: www.example.com


On success, this request yields an empty response:

HTTP/1.1 204 No Content


Typical error response codes include: