1class BaseDatabaseValidation:
 2    """Encapsulate backend-specific validation."""
 3
 4    def __init__(self, connection):
 5        self.connection = connection
 6
 7    def check(self, **kwargs):
 8        return []
 9
10    def check_field(self, field, **kwargs):
11        errors = []
12        # Backends may implement a check_field_type() method.
13        if (
14            hasattr(self, "check_field_type")
15            and
16            # Ignore any related fields.
17            not getattr(field, "remote_field", None)
18        ):
19            # Ignore fields with unsupported features.
20            db_supports_all_required_features = all(
21                getattr(self.connection.features, feature, False)
22                for feature in field.model._meta.required_db_features
23            )
24            if db_supports_all_required_features:
25                field_type = field.db_type(self.connection)
26                # Ignore non-concrete fields.
27                if field_type is not None:
28                    errors.extend(self.check_field_type(field, field_type))
29        return errors