Interface ExternalFieldSchema

Whether NULL is a permitted value at rest. Distinct from IsRequired (see above). When the source system reports neither explicit nullability nor a NOT NULL constraint, leave undefined — consumers default to permissive (nullable). Per the framework's provable-only policy, don't infer NOT NULL from sample data.

Field data type in the external system

Default value expression — surfaced when the source system reports it.

Human-readable description of the field's purpose

If FK, which source object it references

Whether this field is a foreign key

Whether this field is THE primary key of the object. Distinct from IsUniqueKey — an object can have several unique fields (email, phone) of which only one is the PK. Connectors that introspect a source whose docs distinguish PK from unique constraint should set BOTH flags correctly; consumers should treat them independently.

Whether the field is read-only

Whether the field must be provided when creating a new record. Semantically distinct from AllowsNull — required is a create-time constraint; nullable is a record-state constraint. Often related but not always (e.g. a field can be required on create and become nullable later via update; a field can be optional on create with a default applied that produces a non-null stored value).

Whether the field is a unique identifier (may or may not be the PK)

Human-readable label

Maximum length for string types — surfaced when the source system reports it.

API name of the field

Precision for numeric types — surfaced when the source system reports it.

Scale for numeric types — surfaced when the source system reports it.