Create a custom field definition

Platform module

POST/custom-field-definitionscustomFieldDefinitions.create

A custom field on a built-in resource. Creates a custom field definition. Requires `Idempotency-Key`; a replay returns the original response. The organization is derived from the credential or the parent row, never from the body.

Requires the capability org.custom_fields.write.
OAuth scopes: org.
Send an Idempotency-Key header. A replay with the same key returns the original response.
Error statuses: 400, 401, 409, 422, 429. Errors are RFC 9457 problem details.

Request body: CustomFieldDefinitionCreate

customFieldDefinitions.create: CustomFieldDefinitionCreate
Field	Type	Required	Description
target_table	string	Yes	Table the field extends.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
field_key	string	Yes	Field key.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
label	string	Yes	Label.Constraints: length 1 to 300
data_type	string	Yes	Data type.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
required	boolean	No	True when forms require a value.
filterable	boolean	No	True when views filter on the field; it adds a partial index.
sort_order	integer	Yes	Position in forms.Constraints: range 0 to any

{
  "target_table": "app.vendors",
  "field_key": "union_signatory",
  "label": "Union Signatory",
  "data_type": "boolean",
  "required": false,
  "filterable": false,
  "sort_order": 1
}

Response 201: CustomFieldDefinition

customFieldDefinitions.create: CustomFieldDefinition
Field	Type	Required	Description
id	string (uuid)	Yes	Identifier of the custom field definition.
org_id	string (uuid)	Yes	Identifier of the owning organization, derived from the parent row and never accepted from the caller.
created_at	string (date-time)	Yes	When the row was created.
created_by	string (uuid) \| null	Yes	Identifier of the person who created the row; null when a seed, platform or system process created it.
updated_at	string (date-time)	Yes	When the row was last updated.
updated_by	string (uuid) \| null	Yes	Identifier of the person who last updated the row; null when a seed, platform or system process updated it.
target_table	string	Yes	Table the field extends.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
field_key	string	Yes	Field key.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
label	string	Yes	Label.Constraints: length 1 to 300
data_type	string	Yes	Data type.Constraints: pattern ^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$
required	boolean	Yes	True when forms require a value.
filterable	boolean	Yes	True when views filter on the field; it adds a partial index.
sort_order	integer	Yes	Position in forms.Constraints: range 0 to any

{
  "id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
  "org_id": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
  "created_at": "2026-10-08T14:30:00Z",
  "created_by": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
  "updated_at": "2026-10-08T14:30:00Z",
  "updated_by": "0192f1e2-7c3a-7b4d-9e8f-1a2b3c4d5e6f",
  "target_table": "app.vendors",
  "field_key": "union_signatory",
  "label": "Union Signatory",
  "data_type": "boolean",
  "required": false,
  "filterable": false,
  "sort_order": 1
}

Code samples

curl -X POST "$XOS_BASE_URL/custom-field-definitions" \
  -H "Authorization: Bearer $XOS_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{"target_table":"app.vendors","field_key":"union_signatory","label":"Union Signatory","data_type":"boolean","required":false,"filterable":false,"sort_order":1}'

const { data } = await xos.customFieldDefinitions.create({
    "target_table": "app.vendors",
    "field_key": "union_signatory",
    "label": "Union Signatory",
    "data_type": "boolean",
    "required": false,
    "filterable": false,
    "sort_order": 1
  });

response = xos.custom_field_definitions.create({"target_table": "app.vendors", "field_key": "union_signatory", "label": "Union Signatory", "data_type": "boolean", "required": False, "filterable": False, "sort_order": 1})

xos custom-field-definitions create --data '{"target_table":"app.vendors","field_key":"union_signatory","label":"Union Signatory","data_type":"boolean","required":false,"filterable":false,"sort_order":1}'