Update Field

Update an existing contact field by its ID.

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Endpoint

PATCH https://api.campaignlark.com/v1/fields/:id

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Path Parameters

Parameter	Type	Required	Description
id	integer	required	The field ID.

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Request Body

Field	Type	Required	Description
label	string	required	Human-readable display name. 1–32 characters. Must be unique within the workspace.
merge_tag	string	required	The key used to reference this field in contact data payloads. 2–16 characters, lowercase letters and underscores only. Must be unique.
type	string	required	Data type of the field. Must match the field's existing type — the type cannot be changed.
definition	string	conditional	Required for DROPDOWN_SINGLE and DROPDOWN_MULTIPLE types. Comma-separated list of at least 2 unique options.
default_value	string	optional	Value used when no value is provided for this field.
required	boolean	optional	Whether this field must have a value on every contact.

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Sample Request

PATCH https://api.campaignlark.com/v1/fields/6
Content-Type: application/json

{
  "label": "Favorite Color Updated",
  "merge_tag": "fav_color",
  "type": "DROPDOWN_SINGLE",
  "definition": "Red,Blue,Green,Yellow",
  "default_value": "",
  "required": false
}

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Response

Success — 200 OK

{
  "data": {
    "id": 6,
    "label": "Favorite Color Updated",
    "merge_tag": "fav_color",
    "type": "DROPDOWN_SINGLE",
    "definition": "Red,Blue,Green,Yellow",
    "default_value": "",
    "order": 0,
    "immutable": false,
    "required": false
  }
}

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Errors

Status	Message	Cause
404	We were unable to find the field.	Field does not exist in this workspace.
400	This field is immutable and cannot be updated.	Immutable fields (e.g. email_address) cannot be modified.
400	The type of the field cannot be changed.	The type value does not match the field's existing type.
400	Validation error	label is missing, empty, or exceeds 32 characters.
400	Validation error	merge_tag is missing, invalid format, or exceeds 16 characters.
400	Validation error	definition is required for dropdown types and must contain at least 2 unique options.
400	Validation error	A field with the same label or merge_tag already exists.
400	Validation error	An import or export is currently in progress.