Class InlineForeignKeyField

django/forms/models.py:1376–1417

A basic integer field that deals with validating the given value to a given parent instance in an inline.

class InlineForeignKeyField(Field):
    """
    A basic integer field that deals with validating the given value to a
    given parent instance in an inline.
    """

    widget = HiddenInput
    default_error_messages = {
        "invalid_choice": _("The inline value did not match the parent instance."),
    }

    def __init__(self, parent_instance, *args, pk_field=False, to_field=None, **kwargs):
        self.parent_instance = parent_instance
        self.pk_field = pk_field
        self.to_field = to_field
        if self.parent_instance is not None:
            if self.to_field:
                kwargs["initial"] = getattr(self.parent_instance, self.to_field)
            else:
                kwargs["initial"] = self.parent_instance.pk
        kwargs["required"] = False
        super().__init__(*args, **kwargs)

    def clean(self, value):
        if value in self.empty_values:
            if self.pk_field:
                return None
            # if there is no value act as we did before.
            return self.parent_instance
        # ensure the we compare the values as equal types.
        if self.to_field:
            orig = getattr(self.parent_instance, self.to_field)
        else:
            orig = self.parent_instance.pk
        if str(value) != str(orig):
            raise ValidationError(
                self.error_messages["invalid_choice"], code="invalid_choice"
            )
        return self.parent_instance

    def has_changed(self, initial, data):
        return False


class ModelChoiceIteratorValue: