Source code for tortoise.fields.base

from enum import Enum
from typing import (
    TYPE_CHECKING,
    Any,
    Callable,
    Dict,
    Generic,
    List,
    Optional,
    Tuple,
    Type,
    TypeVar,
    Union,
    overload,
)

from pypika.terms import Term

from tortoise.exceptions import ConfigurationError, ValidationError
from tortoise.validators import Validator

if TYPE_CHECKING:  # pragma: nocoverage
    from tortoise.models import Model

VALUE = TypeVar("VALUE")

# TODO: Replace this with an enum
CASCADE = "CASCADE"
RESTRICT = "RESTRICT"
SET_NULL = "SET NULL"
SET_DEFAULT = "SET DEFAULT"
NO_ACTION = "NO ACTION"


class _FieldMeta(type):
    # TODO: Require functions to return field instances instead of this hack
    def __new__(mcs, name: str, bases: Tuple[Type, ...], attrs: dict):
        if len(bases) > 1 and bases[0] is Field:
            # Instantiate class with only the 1st base class (should be Field)
            cls = type.__new__(mcs, name, (bases[0],), attrs)
            # All other base classes are our meta types, we store them in class attributes
            cls.field_type = bases[1] if len(bases) == 2 else Union[bases[1:]]  # type: ignore
            return cls
        return type.__new__(mcs, name, bases, attrs)


[docs]class Field(Generic[VALUE], metaclass=_FieldMeta): """ Base Field type. :param source_field: Provide a source_field name if the DB column name needs to be something specific instead of generated off the field name. :param generated: Is this field DB-generated? :param pk: Is this field a Primary Key? Can only have a single such field on the Model, and if none is specified it will autogenerate a default primary key called ``id``. :param null: Is this field nullable? :param default: A default value for the field if not specified on Model creation. This can also be a callable for dynamic defaults in which case we will call it. The default value will not be part of the schema. :param unique: Is this field unique? :param index: Should this field be indexed by itself? :param description: Field description. Will also appear in ``Tortoise.describe_model()`` and as DB comments in the generated DDL. :param validators: Validators for this field. **Class Attributes:** These attributes needs to be defined when defining an actual field type. .. attribute:: field_type :annotation: Type[Any] The Python type the field is. If adding a type as a mixin, _FieldMeta will automatically set this to that. .. attribute:: indexable :annotation: bool = True Is the field indexable? Set to False if this field can't be indexed reliably. .. attribute:: has_db_field :annotation: bool = True Does this field have a direct corresponding DB column? Or is the field virtualized? .. attribute:: skip_to_python_if_native :annotation: bool = False If the DB driver natively supports this Python type, should we skip it? This is for optimization purposes only, where we don't need to force type conversion between Python and the DB. .. attribute:: allows_generated :annotation: bool = False Is this field able to be DB-generated? .. attribute:: function_cast :annotation: Optional[pypika.Term] = None A casting term that we need to apply in case the DB needs emulation help. .. attribute:: SQL_TYPE :annotation: str The SQL type as a string that the DB will use. .. attribute:: GENERATED_SQL :annotation: str The SQL that instructs the DB to auto-generate this field. Required if ``allows_generated`` is ``True``. **Per-DB overrides:** One can specify per-DB overrides of any of the class attributes, or the ``to_db_value`` or ``to_python_value`` methods. To do so, specify a inner class in the form of :samp:`class _db__{SQL_DIALECT}:` like so: .. code-block:: py3 class _db_sqlite: SQL_TYPE = "VARCHAR(40)" skip_to_python_if_native = False def function_cast(self, term: Term) -> Term: return functions.Cast(term, SqlTypes.NUMERIC) Tortoise will then use the overridden attributes/functions for that dialect. If you need a dynamic attribute, you can use a property. """ # Field_type is a readonly property for the instance, it is set by _FieldMeta field_type: Type[Any] = None # type: ignore indexable: bool = True has_db_field: bool = True skip_to_python_if_native: bool = False allows_generated: bool = False function_cast: Optional[Callable[[Term], Term]] = None SQL_TYPE: str = None # type: ignore GENERATED_SQL: str = None # type: ignore # These methods are just to make IDE/Linters happy: def __new__(cls, *args: Any, **kwargs: Any) -> "Field[VALUE]": return super().__new__(cls) @overload def __get__(self, instance: None, owner: Type["Model"]) -> "Field[VALUE]": ... @overload def __get__(self, instance: "Model", owner: Type["Model"]) -> VALUE: ... def __get__(self, instance: Optional["Model"], owner: Type["Model"]): ... def __init__( self, source_field: Optional[str] = None, generated: bool = False, pk: bool = False, null: bool = False, default: Any = None, unique: bool = False, index: bool = False, description: Optional[str] = None, model: "Optional[Model]" = None, validators: Optional[List[Union[Validator, Callable]]] = None, **kwargs: Any, ) -> None: # TODO: Rename pk to primary_key, alias pk, deprecate # TODO: Rename index to db_index, alias index, deprecate if not self.indexable and (unique or index): raise ConfigurationError(f"{self.__class__.__name__} can't be indexed") if pk and null: raise ConfigurationError( f"{self.__class__.__name__} can't be both null=True and pk=True" ) if pk: index = True unique = True self.source_field = source_field self.generated = generated self.pk = pk self.default = default self.null = null self.unique = unique self.index = index self.model_field_name = "" self.description = description self.docstring: Optional[str] = None self.validators: List[Union[Validator, Callable]] = validators or [] # TODO: consider making this not be set from constructor self.model: Type["Model"] = model # type: ignore self.reference: "Optional[Field]" = None
[docs] def to_db_value(self, value: Any, instance: "Union[Type[Model], Model]") -> Any: """ Converts from the Python type to the DB type. :param value: Current python value in model. :param instance: Model class or Model instance provided to look up. Due to metacoding, to determine if this is an instance reliably, please do a: .. code-block:: py3 if hasattr(instance, "_saved_in_db"): """ if value is not None and not isinstance(value, self.field_type): value = self.field_type(value) # pylint: disable=E1102 self.validate(value) return value
[docs] def to_python_value(self, value: Any) -> Any: """ Converts from the DB type to the Python type. :param value: Value from DB """ if value is not None and not isinstance(value, self.field_type): value = self.field_type(value) # pylint: disable=E1102 self.validate(value) return value
[docs] def validate(self, value: Any): """ Validate whether given value is valid :param value: Value to be validation :raises ValidationError: If validator check is not passed """ for v in self.validators: if self.null and value is None: continue try: if isinstance(value, Enum): v(value.value) else: v(value) except ValidationError as exc: raise ValidationError(f"{self.model_field_name}: {exc}")
@property def required(self) -> bool: """ Returns ``True`` if the field is required to be provided. It needs to be non-nullable and not have a default or be DB-generated to be required. """ return self.default is None and not self.null and not self.generated @property def constraints(self) -> dict: """ Returns a dict with constraints defined in the Pydantic/JSONSchema format. """ return {} def _get_dialects(self) -> Dict[str, dict]: ret = {} for dialect in [key for key in dir(self) if key.startswith("_db_")]: item = {} cls = getattr(self, dialect) try: cls = cls(self) except TypeError: pass for key, val in cls.__dict__.items(): if not key.startswith("_"): item[key] = val ret[dialect[4:]] = item return ret
[docs] def get_db_field_types(self) -> Optional[Dict[str, str]]: """ Returns the DB types for this field. :return: A dictionary that is keyed by dialect. A blank dialect `""` means it is the default DB field type. """ if not self.has_db_field: # pragma: nocoverage return None return { "": getattr(self, "SQL_TYPE"), **{ dialect: _db["SQL_TYPE"] for dialect, _db in self._get_dialects().items() if "SQL_TYPE" in _db }, }
[docs] def get_for_dialect(self, dialect: str, key: str) -> Any: """ Returns a field by dialect override. :param dialect: The requested SQL Dialect. :param key: The attribute/method name. """ dialect_data = self._get_dialects().get(dialect, {}) return dialect_data.get(key, getattr(self, key, None))
[docs] def describe(self, serializable: bool) -> dict: """ Describes the field. :param serializable: ``False`` if you want raw python objects, ``True`` for JSON-serializable data. (Defaults to ``True``) :return: A dictionary containing the field description. (This assumes ``serializable=True``, which is the default): .. code-block:: python3 { "name": str # Field name "field_type": str # Field type "db_column": str # Name of DB column # Optional: Only for pk/data fields "raw_field": str # Name of raw field of the Foreign Key # Optional: Only for Foreign Keys "db_field_types": dict # DB Field types for default and DB overrides "python_type": str # Python type "generated": bool # Is the field generated by the DB? "nullable": bool # Is the column nullable? "unique": bool # Is the field unique? "indexed": bool # Is the field indexed? "default": ... # The default value (coerced to int/float/str/bool/null) "description": str # Description of the field (nullable) "docstring": str # Field docstring (nullable) } When ``serializable=False`` is specified some fields are not coerced to valid JSON types. The changes are: .. code-block:: python3 { "field_type": Field # The Field class used "python_type": Type # The actual Python type "default": ... # The default value as native type OR a callable } """ def _type_name(typ: Type) -> str: if typ.__module__ == "builtins": return typ.__name__ if typ.__module__ == "typing": return str(typ).replace("typing.", "") return f"{typ.__module__}.{typ.__name__}" def type_name(typ: Any) -> Union[str, List[str]]: try: return typ._meta.full_name except (AttributeError, TypeError): pass try: return _type_name(typ) except AttributeError: try: return [_type_name(_typ) for _typ in typ] # pragma: nobranch except TypeError: return str(typ) def default_name(default: Any) -> Optional[Union[int, float, str, bool]]: if isinstance(default, (int, float, str, bool, type(None))): return default if callable(default): return f"<function {default.__module__}.{default.__name__}>" return str(default) field_type = getattr(self, "related_model", self.field_type) desc = { "name": self.model_field_name, "field_type": self.__class__.__name__ if serializable else self.__class__, "db_column": self.source_field or self.model_field_name, "python_type": type_name(field_type) if serializable else field_type, "generated": self.generated, "nullable": self.null, "unique": self.unique, "indexed": self.index or self.unique, "default": default_name(self.default) if serializable else self.default, "description": self.description, "docstring": self.docstring, "constraints": self.constraints, } if self.has_db_field: desc["db_field_types"] = self.get_db_field_types() return desc