Method add_fields

django/forms/models.py:1183–1221

(self, form, index)

        return super().save_new(form, commit=commit)

    def add_fields(self, form, index):
        super().add_fields(form, index)
        if self._pk_field == self.fk:
            name = self._pk_field.name
            kwargs = {"pk_field": True}
        else:
            # The foreign key field might not be on the form, so we poke at the
            # Model field to get the label, since we need that for error
            # messages.
            name = self.fk.name
            kwargs = {
                "label": getattr(
                    form.fields.get(name), "label", capfirst(self.fk.verbose_name)
                )
            }

        # The InlineForeignKeyField assumes that the foreign key relation is
        # based on the parent model's pk. If this isn't the case, set to_field
        # to correctly resolve the initial form value.
        if self.fk.remote_field.field_name != self.fk.remote_field.model._meta.pk.name:
            kwargs["to_field"] = self.fk.remote_field.field_name

        # If we're adding a new object, ignore a parent's auto-generated key
        # as it will be regenerated on the save request.
        if self.instance._state.adding:
            if kwargs.get("to_field") is not None:
                to_field = self.instance._meta.get_field(kwargs["to_field"])
            else:
                to_field = self.instance._meta.pk

            if to_field.has_default() and (
                # Don't ignore a parent's auto-generated key if it's not the
                # parent model's pk and form data is provided.
                to_field.attname == self.fk.remote_field.model._meta.pk.name
                or not form.data
            ):
                setattr(self.instance, to_field.attname, None)

        form.fields[name] = InlineForeignKeyField(self.instance, **kwargs)

    def get_unique_error_message(self, unique_check):
        unique_check = [field for field in unique_check if field != self.fk.name]