Create a custom field

Use this endpoint to create a custom field value on a shipment or container. The field must reference an existing custom field definition.

Request body

Parameter	Required	Description
entity	Yes	Polymorphic relationship to a Shipment or Container
api_slug	Yes	The slug of the custom field definition
value	Yes	The field value (must match the definition’s data type)

Value formats by data type

Data type	Expected value format
short_text	Any string
number	Numeric value
date	Date string (parsed using definition’s default_format or flexible parsing)
datetime	DateTime string
boolean	true or false
enum	String matching one of the definition’s option values
enum_multi	Array of strings matching the definition’s option values

Validation

• Values are validated against the definition’s data type
• Enum values must match one of the definition’s configured options
• The api_slug must reference a definition belonging to your account or a Terminal49 template