The Location Response Header in REST Create Operation

For REST endpoints, the Location response header tells clients where to retrieve a newly created resource. Data API builder (DAB) returns Location for POST inserts. For PUT or PATCH upserts that create new rows, the header may be omitted.

When DAB sets the Location header

Scenario	Status Code	Location Header (current behavior)
POST creates a new row (table)	201 Created	Present: primary key path segments, for example id/123 or categoryid/3/pieceid/1.
POST executes stored procedure returning new rows	201 Created	Present if PK can be derived; may be empty when it can't.
PUT upsert updates existing row	200 OK	Not present
PUT upsert inserts new row (no If-Match)	201 Created	May be omitted; don't rely on Location
PATCH upsert updates existing row	200 OK	Not present
PATCH upsert inserts new row (no If-Match)	201 Created	May be omitted; don't rely on Location
PUT/PATCH with If-Match: * and row missing	404 Not Found	Not present
Any update (row existed)	200 OK	Not present

Behavior

• Composite primary keys appear as ordered segments, for example book_id/1/id/5001 or categoryid/3/pieceid/1.
• Column name mappings (aliases) use the REST-exposed field names in the path.

Example: POST creating a new item

Request

POST /api/Books
Content-Type: application/json

{
  "title": "New Book",
  "publisher_id": 42
}

Response

HTTP/1.1 201 Created
Location: http://localhost:50246/api/Books/id/123
Content-Type: application/json

{
  "id": 123,
  "title": "New Book",
  "publisher_id": 42
}

Client can now GET http://localhost:50246/api/Books/id/123.

Example: POST inserting into composite key table

Request

POST /api/Inventory
Content-Type: application/json

{
  "categoryid": 3,
  "pieceid": 1,
  "categoryName": "SciFi"
}

Response

HTTP/1.1 201 Created
Location: http://localhost:50246/api/Inventory/categoryid/3/pieceid/1
Content-Type: application/json

{
  "categoryid": 3,
  "pieceid": 1,
  "categoryName": "SciFi"
}

Example: PUT updating existing row (no Location)

Request

PUT http://localhost:50246/api/Books/id/1
Content-Type: application/json

{
  "title": "Updated Title"
}

Response

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

{
  "id": 1,
  "title": "Updated Title"
}

(No Location header.)

Example: PUT inserting new row

Request

PUT http://localhost:50246/api/Books/id/500
Content-Type: application/json

{
  "title": "Inserted via PUT",
  "publisher_id": 7
}

Response

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

{
  "id": 500,
  "title": "Inserted via PUT",
  "publisher_id": 7
}

(Location header may be omitted here.)

Example: PUT with If-Match and row missing

Request

PUT http://localhost:50246/api/Books/id/500
If-Match: *
Content-Type: application/json

{
  "title": "Attempted Update"
}

Response

HTTP/1.1 404 Not Found
Content-Type: application/json

{
  "error": "No Update could be performed, record not found"
}

(No Location header.)

Review

• POST with creation: Location is present with the primary key path.
• PUT or PATCH with update: No Location.
• PUT or PATCH with insert: Returns 201 Created; Location may be omitted (don't depend on it).
• When you include If-Match: *, DAB only performs an update if the row already exists. If the row is missing, the request fails with 404 Not Found and no insert is performed, so no Location header is returned.