# ext/hybrid.py # Copyright (C) 2005-2026 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php r"""Define attributes on ORM-mapped classes that have "hybrid" behavior. "hybrid" means the attribute has distinct behaviors defined at the class level and at the instance level. The :mod:`~sqlalchemy.ext.hybrid` extension provides a special form of method decorator and has minimal dependencies on the rest of SQLAlchemy. Its basic theory of operation can work with any descriptor-based expression system. Consider a mapping ``Interval``, representing integer ``start`` and ``end`` values. We can define higher level functions on mapped classes that produce SQL expressions at the class level, and Python expression evaluation at the instance level. Below, each function decorated with :class:`.hybrid_method` or :class:`.hybrid_property` may receive ``self`` as an instance of the class, or may receive the class directly, depending on context:: from __future__ import annotations from sqlalchemy.ext.hybrid import hybrid_method from sqlalchemy.ext.hybrid import hybrid_property from sqlalchemy.orm import DeclarativeBase from sqlalchemy.orm import Mapped from sqlalchemy.orm import mapped_column class Base(DeclarativeBase): pass class Interval(Base): __tablename__ = "interval" id: Mapped[int] = mapped_column(primary_key=True) start: Mapped[int] end: Mapped[int] def __init__(self, start: int, end: int): self.start = start self.end = end @hybrid_property def length(self) -> int: return self.end - self.start @hybrid_method def contains(self, point: int) -> bool: return (self.start <= point) & (point <= self.end) @hybrid_method def intersects(self, other: Interval) -> bool: return self.contains(other.start) | self.contains(other.end) Above, the ``length`` property returns the difference between the ``end`` and ``start`` attributes. With an instance of ``Interval``, this subtraction occurs in Python, using normal Python descriptor mechanics:: >>> i1 = Interval(5, 10) >>> i1.length 5 When dealing with the ``Interval`` class itself, the :class:`.hybrid_property` descriptor evaluates the function body given the ``Interval`` class as the argument, which when evaluated with SQLAlchemy expression mechanics returns a new SQL expression: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> print(select(Interval.length)) {printsql}SELECT interval."end" - interval.start AS length FROM interval{stop} >>> print(select(Interval).filter(Interval.length > 10)) {printsql}SELECT interval.id, interval.start, interval."end" FROM interval WHERE interval."end" - interval.start > :param_1 Filtering methods such as :meth:`.Select.filter_by` are supported with hybrid attributes as well: .. sourcecode:: pycon+sql >>> print(select(Interval).filter_by(length=5)) {printsql}SELECT interval.id, interval.start, interval."end" FROM interval WHERE interval."end" - interval.start = :param_1 The ``Interval`` class example also illustrates two methods, ``contains()`` and ``intersects()``, decorated with :class:`.hybrid_method`. This decorator applies the same idea to methods that :class:`.hybrid_property` applies to attributes. The methods return boolean values, and take advantage of the Python ``|`` and ``&`` bitwise operators to produce equivalent instance-level and SQL expression-level boolean behavior: .. sourcecode:: pycon+sql >>> i1.contains(6) True >>> i1.contains(15) False >>> i1.intersects(Interval(7, 18)) True >>> i1.intersects(Interval(25, 29)) False >>> print(select(Interval).filter(Interval.contains(15))) {printsql}SELECT interval.id, interval.start, interval."end" FROM interval WHERE interval.start <= :start_1 AND interval."end" > :end_1{stop} >>> ia = aliased(Interval) >>> print(select(Interval, ia).filter(Interval.intersects(ia))) {printsql}SELECT interval.id, interval.start, interval."end", interval_1.id AS interval_1_id, interval_1.start AS interval_1_start, interval_1."end" AS interval_1_end FROM interval, interval AS interval_1 WHERE interval.start <= interval_1.start AND interval."end" > interval_1.start OR interval.start <= interval_1."end" AND interval."end" > interval_1."end"{stop} .. _hybrid_distinct_expression: Defining Expression Behavior Distinct from Attribute Behavior -------------------------------------------------------------- In the previous section, our usage of the ``&`` and ``|`` bitwise operators within the ``Interval.contains`` and ``Interval.intersects`` methods was fortunate, considering our functions operated on two boolean values to return a new one. In many cases, the construction of an in-Python function and a SQLAlchemy SQL expression have enough differences that two separate Python expressions should be defined. The :mod:`~sqlalchemy.ext.hybrid` decorator defines a **modifier** :meth:`.hybrid_property.expression` for this purpose. As an example we'll define the radius of the interval, which requires the usage of the absolute value function:: from sqlalchemy import ColumnElement from sqlalchemy import Float from sqlalchemy import func from sqlalchemy import type_coerce class Interval(Base): # ... @hybrid_property def radius(self) -> float: return abs(self.length) / 2 @radius.inplace.expression @classmethod def _radius_expression(cls) -> ColumnElement[float]: return type_coerce(func.abs(cls.length) / 2, Float) In the above example, the :class:`.hybrid_property` first assigned to the name ``Interval.radius`` is amended by a subsequent method called ``Interval._radius_expression``, using the decorator ``@radius.inplace.expression``, which chains together two modifiers :attr:`.hybrid_property.inplace` and :attr:`.hybrid_property.expression`. The use of :attr:`.hybrid_property.inplace` indicates that the :meth:`.hybrid_property.expression` modifier should mutate the existing hybrid object at ``Interval.radius`` in place, without creating a new object. Notes on this modifier and its rationale are discussed in the next section :ref:`hybrid_pep484_naming`. The use of ``@classmethod`` is optional, and is strictly to give typing tools a hint that ``cls`` in this case is expected to be the ``Interval`` class, and not an instance of ``Interval``. .. note:: :attr:`.hybrid_property.inplace` as well as the use of ``@classmethod`` for proper typing support are available as of SQLAlchemy 2.0.4, and will not work in earlier versions. With ``Interval.radius`` now including an expression element, the SQL function ``ABS()`` is returned when accessing ``Interval.radius`` at the class level: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> print(select(Interval).filter(Interval.radius > 5)) {printsql}SELECT interval.id, interval.start, interval."end" FROM interval WHERE abs(interval."end" - interval.start) / :abs_1 > :param_1 .. _hybrid_pep484_naming: Using ``inplace`` to create pep-484 compliant hybrid properties --------------------------------------------------------------- In the previous section, a :class:`.hybrid_property` decorator is illustrated which includes two separate method-level functions being decorated, both to produce a single object attribute referenced as ``Interval.radius``. There are actually several different modifiers we can use for :class:`.hybrid_property` including :meth:`.hybrid_property.expression`, :meth:`.hybrid_property.setter` and :meth:`.hybrid_property.update_expression`. SQLAlchemy's :class:`.hybrid_property` decorator intends that adding on these methods may be done in the identical manner as Python's built-in ``@property`` decorator, where idiomatic use is to continue to redefine the attribute repeatedly, using the **same attribute name** each time, as in the example below that illustrates the use of :meth:`.hybrid_property.setter` and :meth:`.hybrid_property.expression` for the ``Interval.radius`` descriptor:: # correct use, however is not accepted by pep-484 tooling class Interval(Base): # ... @hybrid_property def radius(self): return abs(self.length) / 2 @radius.setter def radius(self, value): self.length = value * 2 @radius.expression def radius(cls): return type_coerce(func.abs(cls.length) / 2, Float) Above, there are three ``Interval.radius`` methods, but as each are decorated, first by the :class:`.hybrid_property` decorator and then by the ``@radius`` name itself, the end effect is that ``Interval.radius`` is a single attribute with three different functions contained within it. This style of use is taken from `Python's documented use of @property `_. It is important to note that the way both ``@property`` as well as :class:`.hybrid_property` work, a **copy of the descriptor is made each time**. That is, each call to ``@radius.expression``, ``@radius.setter`` etc. make a new object entirely. This allows the attribute to be re-defined in subclasses without issue (see :ref:`hybrid_reuse_subclass` later in this section for how this is used). However, the above approach is not compatible with typing tools such as mypy and pyright. Python's own ``@property`` decorator does not have this limitation only because `these tools hardcode the behavior of @property `_, meaning this syntax is not available to SQLAlchemy under :pep:`484` compliance. In order to produce a reasonable syntax while remaining typing compliant, the :attr:`.hybrid_property.inplace` decorator allows the same decorator to be reused with different method names, while still producing a single decorator under one name:: # correct use which is also accepted by pep-484 tooling class Interval(Base): # ... @hybrid_property def radius(self) -> float: return abs(self.length) / 2 @radius.inplace.setter def _radius_setter(self, value: float) -> None: # for example only self.length = value * 2 @radius.inplace.expression @classmethod def _radius_expression(cls) -> ColumnElement[float]: return type_coerce(func.abs(cls.length) / 2, Float) Using :attr:`.hybrid_property.inplace` further qualifies the use of the decorator that a new copy should not be made, thereby maintaining the ``Interval.radius`` name while allowing additional methods ``Interval._radius_setter`` and ``Interval._radius_expression`` to be differently named. .. versionadded:: 2.0.4 Added :attr:`.hybrid_property.inplace` to allow less verbose construction of composite :class:`.hybrid_property` objects while not having to use repeated method names. Additionally allowed the use of ``@classmethod`` within :attr:`.hybrid_property.expression`, :attr:`.hybrid_property.update_expression`, and :attr:`.hybrid_property.comparator` to allow typing tools to identify ``cls`` as a class and not an instance in the method signature. Defining Setters ---------------- The :meth:`.hybrid_property.setter` modifier allows the construction of a custom setter method, that can modify values on the object:: class Interval(Base): # ... @hybrid_property def length(self) -> int: return self.end - self.start @length.inplace.setter def _length_setter(self, value: int) -> None: self.end = self.start + value The ``length(self, value)`` method is now called upon set:: >>> i1 = Interval(5, 10) >>> i1.length 5 >>> i1.length = 12 >>> i1.end 17 .. _hybrid_bulk_update: Supporting ORM Bulk INSERT and UPDATE ------------------------------------- Hybrids have support for use in ORM Bulk INSERT/UPDATE operations described at :ref:`orm_expression_update_delete`. There are two distinct hooks that may be used supply a hybrid value within a DML operation: 1. The :meth:`.hybrid_property.update_expression` hook indicates a method that can provide one or more expressions to render in the SET clause of an UPDATE or INSERT statement, in response to when a hybrid attribute is referenced directly in the :meth:`.UpdateBase.values` method; i.e. the use shown in :ref:`orm_queryguide_update_delete_where` and :ref:`orm_queryguide_insert_values` 2. The :meth:`.hybrid_property.bulk_dml` hook indicates a method that can intercept individual parameter dictionaries sent to :meth:`_orm.Session.execute`, i.e. the use shown at :ref:`orm_queryguide_bulk_insert` as well as :ref:`orm_queryguide_bulk_update`. Using update_expression with update.values() and insert.values() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The :meth:`.hybrid_property.update_expression` decorator indicates a method that is invoked when a hybrid is used in the :meth:`.ValuesBase.values` clause of an :func:`_sql.update` or :func:`_sql.insert` statement. It returns a list of tuple pairs ``[(x1, y1), (x2, y2), ...]`` which will expand into the SET clause of an UPDATE statement as ``SET x1=y1, x2=y2, ...``. The :func:`_sql.from_dml_column` construct is often useful as it can create a SQL expression that refers to another column that may also present in the same INSERT or UPDATE statement, alternatively falling back to referring to the original column if such an expression is not present. In the example below, the ``total_price`` hybrid will derive the ``price`` column, by taking the given "total price" value and dividing it by a ``tax_rate`` value that is also present in the :meth:`.ValuesBase.values` call:: from sqlalchemy import from_dml_column class Product(Base): __tablename__ = "product" id: Mapped[int] = mapped_column(primary_key=True) price: Mapped[float] tax_rate: Mapped[float] @hybrid_property def total_price(self) -> float: return self.price * (1 + self.tax_rate) @total_price.inplace.update_expression @classmethod def _total_price_update_expression( cls, value: Any ) -> List[Tuple[Any, Any]]: return [(cls.price, value / (1 + from_dml_column(cls.tax_rate)))] When used in an UPDATE statement, :func:`_sql.from_dml_column` creates a reference to the ``tax_rate`` column that will use the value passed to the :meth:`.ValuesBase.values` method, rather than the existing value on the column in the database. This allows the hybrid to access other values being updated in the same statement: .. sourcecode:: pycon+sql >>> from sqlalchemy import update >>> print( ... update(Product).values( ... {Product.tax_rate: 0.08, Product.total_price: 125.00} ... ) ... ) {printsql}UPDATE product SET tax_rate=:tax_rate, price=(:total_price / (:tax_rate + :param_1)) When the column referenced by :func:`_sql.from_dml_column` (in this case ``product.tax_rate``) is omitted from :meth:`.ValuesBase.values`, the rendered expression falls back to using the original column: .. sourcecode:: pycon+sql >>> from sqlalchemy import update >>> print(update(Product).values({Product.total_price: 125.00})) {printsql}UPDATE product SET price=(:total_price / (tax_rate + :param_1)) Using bulk_dml to intercept bulk parameter dictionaries ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. versionadded:: 2.1 For bulk operations that pass a list of parameter dictionaries to methods like :meth:`.Session.execute`, the :meth:`.hybrid_property.bulk_dml` decorator provides a hook that can receive each dictionary and populate it with new values. The implementation for the :meth:`.hybrid_property.bulk_dml` hook can retrieve other column values from the parameter dictionary:: from typing import MutableMapping class Product(Base): __tablename__ = "product" id: Mapped[int] = mapped_column(primary_key=True) price: Mapped[float] tax_rate: Mapped[float] @hybrid_property def total_price(self) -> float: return self.price * (1 + self.tax_rate) @total_price.inplace.bulk_dml @classmethod def _total_price_bulk_dml( cls, mapping: MutableMapping[str, Any], value: float ) -> None: mapping["price"] = value / (1 + mapping["tax_rate"]) This allows for bulk INSERT/UPDATE with derived values:: # Bulk INSERT session.execute( insert(Product), [ {"tax_rate": 0.08, "total_price": 125.00}, {"tax_rate": 0.05, "total_price": 110.00}, ], ) Note that the method decorated by :meth:`.hybrid_property.bulk_dml` is invoked only with parameter dictionaries and does not have the ability to use SQL expressions in the given dictionaries, only literal Python values that will be passed to parameters in the INSERT or UPDATE statement. .. seealso:: :ref:`orm_expression_update_delete` - includes background on ORM-enabled UPDATE statements Working with Relationships -------------------------- There's no essential difference when creating hybrids that work with related objects as opposed to column-based data. The need for distinct expressions tends to be greater. The two variants we'll illustrate are the "join-dependent" hybrid, and the "correlated subquery" hybrid. Join-Dependent Relationship Hybrid ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Consider the following declarative mapping which relates a ``User`` to a ``SavingsAccount``:: from __future__ import annotations from decimal import Decimal from typing import cast from typing import List from typing import Optional from sqlalchemy import ForeignKey from sqlalchemy import Numeric from sqlalchemy import String from sqlalchemy import SQLColumnExpression from sqlalchemy.ext.hybrid import hybrid_property from sqlalchemy.orm import DeclarativeBase from sqlalchemy.orm import Mapped from sqlalchemy.orm import mapped_column from sqlalchemy.orm import relationship class Base(DeclarativeBase): pass class SavingsAccount(Base): __tablename__ = "account" id: Mapped[int] = mapped_column(primary_key=True) user_id: Mapped[int] = mapped_column(ForeignKey("user.id")) balance: Mapped[Decimal] = mapped_column(Numeric(15, 5)) owner: Mapped[User] = relationship(back_populates="accounts") class User(Base): __tablename__ = "user" id: Mapped[int] = mapped_column(primary_key=True) name: Mapped[str] = mapped_column(String(100)) accounts: Mapped[List[SavingsAccount]] = relationship( back_populates="owner", lazy="selectin" ) @hybrid_property def balance(self) -> Optional[Decimal]: if self.accounts: return self.accounts[0].balance else: return None @balance.inplace.setter def _balance_setter(self, value: Optional[Decimal]) -> None: assert value is not None if not self.accounts: account = SavingsAccount(owner=self) else: account = self.accounts[0] account.balance = value @balance.inplace.expression @classmethod def _balance_expression(cls) -> SQLColumnExpression[Optional[Decimal]]: return cast( "SQLColumnExpression[Optional[Decimal]]", SavingsAccount.balance, ) The above hybrid property ``balance`` works with the first ``SavingsAccount`` entry in the list of accounts for this user. The in-Python getter/setter methods can treat ``accounts`` as a Python list available on ``self``. .. tip:: The ``User.balance`` getter in the above example accesses the ``self.accounts`` collection, which will normally be loaded via the :func:`.selectinload` loader strategy configured on the ``User.balance`` :func:`_orm.relationship`. The default loader strategy when not otherwise stated on :func:`_orm.relationship` is :func:`.lazyload`, which emits SQL on demand. When using asyncio, on-demand loaders such as :func:`.lazyload` are not supported, so care should be taken to ensure the ``self.accounts`` collection is accessible to this hybrid accessor when using asyncio. At the expression level, it's expected that the ``User`` class will be used in an appropriate context such that an appropriate join to ``SavingsAccount`` will be present: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> print( ... select(User, User.balance) ... .join(User.accounts) ... .filter(User.balance > 5000) ... ) {printsql}SELECT "user".id AS user_id, "user".name AS user_name, account.balance AS account_balance FROM "user" JOIN account ON "user".id = account.user_id WHERE account.balance > :balance_1 Note however, that while the instance level accessors need to worry about whether ``self.accounts`` is even present, this issue expresses itself differently at the SQL expression level, where we basically would use an outer join: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> from sqlalchemy import or_ >>> print( ... select(User, User.balance) ... .outerjoin(User.accounts) ... .filter(or_(User.balance < 5000, User.balance == None)) ... ) {printsql}SELECT "user".id AS user_id, "user".name AS user_name, account.balance AS account_balance FROM "user" LEFT OUTER JOIN account ON "user".id = account.user_id WHERE account.balance < :balance_1 OR account.balance IS NULL Correlated Subquery Relationship Hybrid ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ We can, of course, forego being dependent on the enclosing query's usage of joins in favor of the correlated subquery, which can portably be packed into a single column expression. A correlated subquery is more portable, but often performs more poorly at the SQL level. Using the same technique illustrated at :ref:`mapper_column_property_sql_expressions`, we can adjust our ``SavingsAccount`` example to aggregate the balances for *all* accounts, and use a correlated subquery for the column expression:: from __future__ import annotations from decimal import Decimal from typing import List from sqlalchemy import ForeignKey from sqlalchemy import func from sqlalchemy import Numeric from sqlalchemy import select from sqlalchemy import SQLColumnExpression from sqlalchemy import String from sqlalchemy.ext.hybrid import hybrid_property from sqlalchemy.orm import DeclarativeBase from sqlalchemy.orm import Mapped from sqlalchemy.orm import mapped_column from sqlalchemy.orm import relationship class Base(DeclarativeBase): pass class SavingsAccount(Base): __tablename__ = "account" id: Mapped[int] = mapped_column(primary_key=True) user_id: Mapped[int] = mapped_column(ForeignKey("user.id")) balance: Mapped[Decimal] = mapped_column(Numeric(15, 5)) owner: Mapped[User] = relationship(back_populates="accounts") class User(Base): __tablename__ = "user" id: Mapped[int] = mapped_column(primary_key=True) name: Mapped[str] = mapped_column(String(100)) accounts: Mapped[List[SavingsAccount]] = relationship( back_populates="owner", lazy="selectin" ) @hybrid_property def balance(self) -> Decimal: return sum( (acc.balance for acc in self.accounts), start=Decimal("0") ) @balance.inplace.expression @classmethod def _balance_expression(cls) -> SQLColumnExpression[Decimal]: return ( select(func.sum(SavingsAccount.balance)) .where(SavingsAccount.user_id == cls.id) .label("total_balance") ) The above recipe will give us the ``balance`` column which renders a correlated SELECT: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> print(select(User).filter(User.balance > 400)) {printsql}SELECT "user".id, "user".name FROM "user" WHERE ( SELECT sum(account.balance) AS sum_1 FROM account WHERE account.user_id = "user".id ) > :param_1 .. _hybrid_custom_comparators: Building Custom Comparators --------------------------- The hybrid property also includes a helper that allows construction of custom comparators. A comparator object allows one to customize the behavior of each SQLAlchemy expression operator individually. They are useful when creating custom types that have some highly idiosyncratic behavior on the SQL side. .. note:: The :meth:`.hybrid_property.comparator` decorator introduced in this section **replaces** the use of the :meth:`.hybrid_property.expression` decorator. They cannot be used together. The example class below allows case-insensitive comparisons on the attribute named ``word_insensitive``:: from __future__ import annotations from typing import Any from sqlalchemy import ColumnElement from sqlalchemy import func from sqlalchemy.ext.hybrid import Comparator from sqlalchemy.ext.hybrid import hybrid_property from sqlalchemy.orm import DeclarativeBase from sqlalchemy.orm import Mapped from sqlalchemy.orm import mapped_column class Base(DeclarativeBase): pass class CaseInsensitiveComparator(Comparator[str]): def __eq__(self, other: Any) -> ColumnElement[bool]: # type: ignore[override] # noqa: E501 return func.lower(self.__clause_element__()) == func.lower(other) class SearchWord(Base): __tablename__ = "searchword" id: Mapped[int] = mapped_column(primary_key=True) word: Mapped[str] @hybrid_property def word_insensitive(self) -> str: return self.word.lower() @word_insensitive.inplace.comparator @classmethod def _word_insensitive_comparator(cls) -> CaseInsensitiveComparator: return CaseInsensitiveComparator(cls.word) Above, SQL expressions against ``word_insensitive`` will apply the ``LOWER()`` SQL function to both sides: .. sourcecode:: pycon+sql >>> from sqlalchemy import select >>> print(select(SearchWord).filter_by(word_insensitive="Trucks")) {printsql}SELECT searchword.id, searchword.word FROM searchword WHERE lower(searchword.word) = lower(:lower_1) The ``CaseInsensitiveComparator`` above implements part of the :class:`.ColumnOperators` interface. A "coercion" operation like lowercasing can be applied to all comparison operations (i.e. ``eq``, ``lt``, ``gt``, etc.) using :meth:`.Operators.operate`:: class CaseInsensitiveComparator(Comparator): def operate(self, op, other, **kwargs): return op( func.lower(self.__clause_element__()), func.lower(other), **kwargs, ) .. _hybrid_reuse_subclass: Reusing Hybrid Properties across Subclasses ------------------------------------------- A hybrid can be referred to from a superclass, to allow modifying methods like :meth:`.hybrid_property.getter`, :meth:`.hybrid_property.setter` to be used to redefine those methods on a subclass. This is similar to how the standard Python ``@property`` object works:: class FirstNameOnly(Base): # ... first_name: Mapped[str] @hybrid_property def name(self) -> str: return self.first_name @name.inplace.setter def _name_setter(self, value: str) -> None: self.first_name = value class FirstNameLastName(FirstNameOnly): # ... last_name: Mapped[str] # 'inplace' is not used here; calling getter creates a copy # of FirstNameOnly.name that is local to FirstNameLastName @FirstNameOnly.name.getter def name(self) -> str: return self.first_name + " " + self.last_name @name.inplace.setter def _name_setter(self, value: str) -> None: self.first_name, self.last_name = value.split(" ", 1) Above, the ``FirstNameLastName`` class refers to the hybrid from ``FirstNameOnly.name`` to repurpose its getter and setter for the subclass. When overriding :meth:`.hybrid_property.expression` and :meth:`.hybrid_property.comparator` alone as the first reference to the superclass, these names conflict with the same-named accessors on the class- level :class:`.QueryableAttribute` object returned at the class level. To override these methods when referring directly to the parent class descriptor, add the special qualifier :attr:`.hybrid_property.overrides`, which will de- reference the instrumented attribute back to the hybrid object:: class FirstNameLastName(FirstNameOnly): # ... last_name: Mapped[str] @FirstNameOnly.name.overrides.expression @classmethod def name(cls): return func.concat(cls.first_name, " ", cls.last_name) .. _hybrid_value_objects: Hybrid Value Objects -------------------- In the example shown previously at :ref:`hybrid_custom_comparators`, if we were to compare the ``word_insensitive`` attribute of a ``SearchWord`` instance to a plain Python string, the plain Python string would not be coerced to lower case - the ``CaseInsensitiveComparator`` we built, being returned by ``@word_insensitive.comparator``, only applies to the SQL side. A more comprehensive form of the custom comparator is to construct a **Hybrid Value Object**. This technique applies the target value or expression to a value object which is then returned by the accessor in all cases. The value object allows control of all operations upon the value as well as how compared values are treated, both on the SQL expression side as well as the Python value side. Replacing the previous ``CaseInsensitiveComparator`` class with a new ``CaseInsensitiveWord`` class:: from sqlalchemy import func from sqlalchemy.ext.hybrid import Comparator class CaseInsensitiveWord(Comparator): "Hybrid value representing a lower case representation of a word." def __init__(self, word): if isinstance(word, str): self.word = word.lower() else: self.word = func.lower(word) def operate(self, op, other, **kwargs): if not isinstance(other, CaseInsensitiveWord): other = CaseInsensitiveWord(other) return op(self.word, other.word, **kwargs) def __clause_element__(self): return self.word def __str__(self): return self.word key = "word" "Label to apply to Query tuple results" Above, the ``CaseInsensitiveWord`` object represents ``self.word``, which may be a SQL function, or may be a Python native string. The hybrid value object should implement ``__clause_element__()``, which allows the object to be coerced into a SQL-capable value when used in SQL expression constructs, as well as Python comparison methods such as ``__eq__()``, which is accomplished in the above example by subclassing :class:`.hybrid.Comparator` and overriding the ``operate()`` method. .. topic:: Building the Value object with dataclasses Hybrid value objects may also be implemented as Python dataclasses. If modification to values upon construction is needed, use the ``__post_init__()`` dataclasses method. Instance variables that work in a "hybrid" fashion may be instance of a plain Python value, or an instance of :class:`.SQLColumnExpression` genericized against that type. Also make sure to disable dataclass comparison features, as the :class:`.hybrid.Comparator` class provides these:: from sqlalchemy import func from sqlalchemy.ext.hybrid import Comparator from dataclasses import dataclass @dataclass(eq=False) class CaseInsensitiveWord(Comparator): word: str | SQLColumnExpression[str] def __post_init__(self): if isinstance(self.word, str): self.word = self.word.lower() else: self.word = func.lower(self.word) def operate(self, op, other, **kwargs): if not isinstance(other, CaseInsensitiveWord): other = CaseInsensitiveWord(other) return op(self.word, other.word, **kwargs) def __clause_element__(self): return self.word With ``__clause_element__()`` provided, our ``SearchWord`` class can now deliver the ``CaseInsensitiveWord`` object unconditionally from a single hybrid method, returning an object that behaves appropriately in both value-based and SQL contexts:: class SearchWord(Base): __tablename__ = "searchword" id: Mapped[int] = mapped_column(primary_key=True) word: Mapped[str] @hybrid_property def word_insensitive(self) -> CaseInsensitiveWord: return CaseInsensitiveWord(self.word) The class-level version of ``CaseInsensitiveWord`` will work in SQL constructs: .. sourcecode:: pycon+sql >>> print(select(SearchWord).filter(SearchWord.word_insensitive == "Trucks")) {printsql}SELECT searchword.id AS searchword_id, searchword.word AS searchword_word FROM searchword WHERE lower(searchword.word) = :lower_1 By also subclassing :class:`.hybrid.Comparator` and providing an implementation for ``operate()``, the ``word_insensitive`` attribute also has case-insensitive comparison behavior universally, including SQL expression and Python expression (note the Python value is converted to lower case on the Python side here): .. sourcecode:: pycon+sql >>> from sqlalchemy.orm import aliased >>> sw1 = aliased(SearchWord) >>> sw2 = aliased(SearchWord) >>> print( ... select(sw1.word_insensitive, sw2.word_insensitive).filter( ... sw1.word_insensitive > sw2.word_insensitive ... ) ... ) {printsql}SELECT lower(searchword_1.word) AS lower_1, lower(searchword_2.word) AS lower_2 FROM searchword AS searchword_1, searchword AS searchword_2 WHERE lower(searchword_1.word) > lower(searchword_2.word) Python only expression:: >>> ws1 = SearchWord(word="SomeWord") >>> ws1.word_insensitive == "sOmEwOrD" True >>> ws1.word_insensitive == "XOmEwOrX" False >>> print(ws1.word_insensitive) someword The Hybrid Value pattern is very useful for any kind of value that may have multiple representations, such as timestamps, time deltas, units of measurement, currencies and encrypted passwords. .. seealso:: `Hybrids and Value Agnostic Types `_ - on the techspot.zzzeek.org blog `Value Agnostic Types, Part II `_ - on the techspot.zzzeek.org blog .. _composite_hybrid_value_objects: Composite Hybrid Value Objects ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The functionality of :ref:`hybrid_value_objects` may also be expanded to support "composite" forms; in this pattern, SQLAlchemy hybrids begin to approximate most (though not all) the same functionality that is available from the ORM natively via the :ref:`mapper_composite` feature. We can imitate the example of ``Point`` and ``Vertex`` from that section using hybrids, where ``Point`` is modified to become a Hybrid Value Object:: from dataclasses import dataclass from sqlalchemy import tuple_ from sqlalchemy.ext.hybrid import Comparator from sqlalchemy import SQLColumnExpression @dataclass(eq=False) class Point(Comparator): x: int | SQLColumnExpression[int] y: int | SQLColumnExpression[int] def operate(self, op, other, **kwargs): return op(self.x, other.x) & op(self.y, other.y) def __clause_element__(self): return tuple_(self.x, self.y) Above, the ``operate()`` method is where the most "hybrid" behavior takes place, making use of ``op()`` (the Python operator function in use) along with the the bitwise ``&`` operator provides us with the SQL AND operator in a SQL context, and boolean "and" in a Python boolean context. Following from there, the owning ``Vertex`` class now uses hybrids to represent ``start`` and ``end``:: from sqlalchemy.orm import DeclarativeBase, Mapped from sqlalchemy.orm import mapped_column from sqlalchemy.ext.hybrid import hybrid_property class Base(DeclarativeBase): pass class Vertex(Base): __tablename__ = "vertices" id: Mapped[int] = mapped_column(primary_key=True) x1: Mapped[int] y1: Mapped[int] x2: Mapped[int] y2: Mapped[int] @hybrid_property def start(self) -> Point: return Point(self.x1, self.y1) @start.inplace.setter def _set_start(self, value: Point) -> None: self.x1 = value.x self.y1 = value.y @hybrid_property def end(self) -> Point: return Point(self.x2, self.y2) @end.inplace.setter def _set_end(self, value: Point) -> None: self.x2 = value.x self.y2 = value.y def __repr__(self) -> str: return f"Vertex(start={self.start}, end={self.end})" Using the above mapping, we can use expressions at the Python or SQL level using ``Vertex.start`` and ``Vertex.end``:: >>> v1 = Vertex(start=Point(3, 4), end=Point(15, 10)) >>> v1.end == Point(15, 10) True >>> stmt = ( ... select(Vertex) ... .where(Vertex.start == Point(3, 4)) ... .where(Vertex.end < Point(7, 8)) ... ) >>> print(stmt) SELECT vertices.id, vertices.x1, vertices.y1, vertices.x2, vertices.y2 FROM vertices WHERE vertices.x1 = :x1_1 AND vertices.y1 = :y1_1 AND vertices.x2 < :x2_1 AND vertices.y2 < :y2_1 DML Support for Composite Value Objects ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Composite value objects like ``Point`` can also be used with the ORM's DML features. The :meth:`.hybrid_property.update_expression` decorator allows the hybrid to expand a composite value into multiple column assignments in UPDATE and INSERT statements:: class Location(Base): __tablename__ = "location" id: Mapped[int] = mapped_column(primary_key=True) x: Mapped[int] y: Mapped[int] @hybrid_property def coordinates(self) -> Point: return Point(self.x, self.y) @coordinates.inplace.update_expression @classmethod def _coordinates_update_expression( cls, value: Any ) -> List[Tuple[Any, Any]]: assert isinstance(value, Point) return [(cls.x, value.x), (cls.y, value.y)] This allows UPDATE statements to work with the composite value: .. sourcecode:: pycon+sql >>> from sqlalchemy import update >>> print( ... update(Location) ... .where(Location.id == 5) ... .values({Location.coordinates: Point(25, 17)}) ... ) {printsql}UPDATE location SET x=:x, y=:y WHERE location.id = :id_1 For bulk operations that use parameter dictionaries, the :meth:`.hybrid_property.bulk_dml` decorator provides a hook to convert composite values into individual column values:: from typing import MutableMapping class Location(Base): # ... (same as above) @coordinates.inplace.bulk_dml @classmethod def _coordinates_bulk_dml( cls, mapping: MutableMapping[str, Any], value: Point ) -> None: mapping["x"] = value.x mapping["y"] = value.y This enables bulk operations with composite values:: # Bulk INSERT session.execute( insert(Location), [ {"id": 1, "coordinates": Point(10, 20)}, {"id": 2, "coordinates": Point(30, 40)}, ], ) # Bulk UPDATE session.execute( update(Location), [ {"id": 1, "coordinates": Point(15, 25)}, {"id": 2, "coordinates": Point(35, 45)}, ], ) """ # noqa from __future__ import annotations from typing import Any from typing import Callable from typing import cast from typing import Concatenate from typing import Generic from typing import List from typing import Literal from typing import MutableMapping from typing import Optional from typing import overload from typing import ParamSpec from typing import Protocol from typing import Sequence from typing import Tuple from typing import Type from typing import TYPE_CHECKING from typing import TypeVar from typing import Union from .. import exc from .. import util from ..orm import attributes from ..orm import InspectionAttrExtensionType from ..orm import interfaces from ..orm import ORMDescriptor from ..orm.attributes import QueryableAttribute from ..sql import roles from ..sql._typing import is_has_clause_element from ..sql.elements import ColumnElement from ..sql.elements import SQLCoreOperations from ..util.typing import Self if TYPE_CHECKING: from ..orm.interfaces import MapperProperty from ..orm.util import AliasedInsp from ..sql import SQLColumnExpression from ..sql._typing import _ColumnExpressionArgument from ..sql._typing import _DMLColumnArgument from ..sql._typing import _HasClauseElement from ..sql._typing import _InfoType from ..sql.operators import OperatorType _P = ParamSpec("_P") _R = TypeVar("_R") _T = TypeVar("_T", bound=Any) _TE = TypeVar("_TE", bound=Any) _T_co = TypeVar("_T_co", bound=Any, covariant=True) _T_con = TypeVar("_T_con", bound=Any, contravariant=True) class HybridExtensionType(InspectionAttrExtensionType): HYBRID_METHOD = "HYBRID_METHOD" """Symbol indicating an :class:`InspectionAttr` that's of type :class:`.hybrid_method`. Is assigned to the :attr:`.InspectionAttr.extension_type` attribute. .. seealso:: :attr:`_orm.Mapper.all_orm_attributes` """ HYBRID_PROPERTY = "HYBRID_PROPERTY" """Symbol indicating an :class:`InspectionAttr` that's of type :class:`.hybrid_method`. Is assigned to the :attr:`.InspectionAttr.extension_type` attribute. .. seealso:: :attr:`_orm.Mapper.all_orm_attributes` """ class _HybridGetterType(Protocol[_T_co]): def __call__(s, self: Any, /) -> _T_co: ... class _HybridSetterType(Protocol[_T_con]): def __call__(s, self: Any, value: _T_con, /) -> None: ... class _HybridUpdaterType(Protocol[_T_con]): def __call__( s, cls: Any, value: Union[_T_con, _ColumnExpressionArgument[_T_con]], ) -> List[Tuple[_DMLColumnArgument, Any]]: ... class _HybridBulkDMLType(Protocol[_T_co]): def __call__( s, cls: Any, mapping: MutableMapping[str, Any], value: Any, ) -> Any: ... class _HybridDeleterType(Protocol[_T_co]): def __call__(s, self: Any, /) -> None: ... class _HybridExprCallableType(Protocol[_T_co]): def __call__( s, cls: Any, / ) -> Union[_HasClauseElement[_T_co], SQLColumnExpression[_T_co]]: ... class _HybridComparatorCallableType(Protocol[_T]): def __call__(self, cls: Any) -> Comparator[_T]: ... class _HybridClassLevelAccessor(QueryableAttribute[_T]): """Describe the object returned by a hybrid_property() when called as a class-level descriptor. """ if TYPE_CHECKING: def getter( self, fget: _HybridGetterType[_T] ) -> hybrid_property[_T]: ... def setter( self, fset: _HybridSetterType[_T] ) -> hybrid_property[_T]: ... def deleter( self, fdel: _HybridDeleterType[_T] ) -> hybrid_property[_T]: ... @property def overrides(self) -> hybrid_property[_T]: ... def update_expression( self, meth: _HybridUpdaterType[_T] ) -> hybrid_property[_T]: ... def bulk_dml( self, meth: _HybridBulkDMLType[_T] ) -> hybrid_property[_T]: ... class hybrid_method(interfaces.InspectionAttrInfo, Generic[_P, _R]): """A decorator which allows definition of a Python object method with both instance-level and class-level behavior. """ is_attribute = True extension_type = HybridExtensionType.HYBRID_METHOD def __init__( self, func: Callable[Concatenate[Any, _P], _R], expr: Optional[ Callable[Concatenate[Any, _P], SQLCoreOperations[_R]] ] = None, ): """Create a new :class:`.hybrid_method`. Usage is typically via decorator:: from sqlalchemy.ext.hybrid import hybrid_method class SomeClass: @hybrid_method def value(self, x, y): return self._value + x + y @value.expression @classmethod def value(cls, x, y): return func.some_function(cls._value, x, y) """ self.func = func if expr is not None: self.expression(expr) else: self.expression(func) # type: ignore[arg-type] @property def inplace(self) -> Self: """Return the inplace mutator for this :class:`.hybrid_method`. The :class:`.hybrid_method` class already performs "in place" mutation when the :meth:`.hybrid_method.expression` decorator is called, so this attribute returns Self. .. versionadded:: 2.0.4 .. seealso:: :ref:`hybrid_pep484_naming` """ return self @overload def __get__( self, instance: Literal[None], owner: Type[object] ) -> Callable[_P, SQLCoreOperations[_R]]: ... @overload def __get__( self, instance: object, owner: Type[object] ) -> Callable[_P, _R]: ... def __get__( self, instance: Optional[object], owner: Type[object] ) -> Union[Callable[_P, _R], Callable[_P, SQLCoreOperations[_R]]]: if instance is None: return self.expr.__get__(owner, owner) # type: ignore[no-any-return] # noqa: E501 else: return self.func.__get__(instance, owner) # type: ignore[no-any-return] # noqa: E501 def expression( self, expr: Callable[Concatenate[Any, _P], SQLCoreOperations[_R]] ) -> hybrid_method[_P, _R]: """Provide a modifying decorator that defines a SQL-expression producing method.""" self.expr = expr if not self.expr.__doc__: self.expr.__doc__ = self.func.__doc__ return self def _unwrap_classmethod(meth: _T) -> _T: if isinstance(meth, classmethod): return meth.__func__ # type: ignore[return-value] else: return meth class hybrid_property(interfaces.InspectionAttrInfo, ORMDescriptor[_T]): """A decorator which allows definition of a Python descriptor with both instance-level and class-level behavior. """ is_attribute = True extension_type = HybridExtensionType.HYBRID_PROPERTY __name__: str def __init__( self, fget: _HybridGetterType[_T], fset: Optional[_HybridSetterType[_T]] = None, fdel: Optional[_HybridDeleterType[_T]] = None, expr: Optional[_HybridExprCallableType[_T]] = None, custom_comparator: Optional[Comparator[_T]] = None, update_expr: Optional[_HybridUpdaterType[_T]] = None, bulk_dml_setter: Optional[_HybridBulkDMLType[_T]] = None, ): """Create a new :class:`.hybrid_property`. Usage is typically via decorator:: from sqlalchemy.ext.hybrid import hybrid_property class SomeClass: @hybrid_property def value(self): return self._value @value.setter def value(self, value): self._value = value """ self.fget = fget self.fset = fset self.fdel = fdel self.expr = _unwrap_classmethod(expr) self.custom_comparator = _unwrap_classmethod(custom_comparator) self.update_expr = _unwrap_classmethod(update_expr) self.bulk_dml_setter = _unwrap_classmethod(bulk_dml_setter) util.update_wrapper(self, fget) # type: ignore[arg-type] @overload def __get__(self, instance: Any, owner: Literal[None]) -> Self: ... @overload def __get__( self, instance: Literal[None], owner: Type[object] ) -> _HybridClassLevelAccessor[_T]: ... @overload def __get__(self, instance: object, owner: Type[object]) -> _T: ... def __get__( self, instance: Optional[object], owner: Optional[Type[object]] ) -> Union[hybrid_property[_T], _HybridClassLevelAccessor[_T], _T]: if owner is None: return self elif instance is None: return self._expr_comparator(owner) else: return self.fget(instance) def __set__( self, instance: object, value: Union[SQLCoreOperations[_T], _T] ) -> None: if self.fset is None: raise AttributeError("can't set attribute") self.fset(instance, value) # type: ignore[arg-type] def __delete__(self, instance: object) -> None: if self.fdel is None: raise AttributeError("can't delete attribute") self.fdel(instance) def _copy(self, **kw: Any) -> hybrid_property[_T]: defaults = { key: value for key, value in self.__dict__.items() if not key.startswith("_") } defaults.update(**kw) return type(self)(**defaults) @property def overrides(self) -> Self: """Prefix for a method that is overriding an existing attribute. The :attr:`.hybrid_property.overrides` accessor just returns this hybrid object, which when called at the class level from a parent class, will de-reference the "instrumented attribute" normally returned at this level, and allow modifying decorators like :meth:`.hybrid_property.expression` and :meth:`.hybrid_property.comparator` to be used without conflicting with the same-named attributes normally present on the :class:`.QueryableAttribute`:: class SuperClass: # ... @hybrid_property def foobar(self): return self._foobar class SubClass(SuperClass): # ... @SuperClass.foobar.overrides.expression def foobar(cls): return func.subfoobar(self._foobar) .. seealso:: :ref:`hybrid_reuse_subclass` """ return self class _InPlace(Generic[_TE]): """A builder helper for .hybrid_property. .. versionadded:: 2.0.4 """ __slots__ = ("attr",) def __init__(self, attr: hybrid_property[_TE]): self.attr = attr def _set(self, **kw: Any) -> hybrid_property[_TE]: for k, v in kw.items(): setattr(self.attr, k, _unwrap_classmethod(v)) return self.attr def getter(self, fget: _HybridGetterType[_TE]) -> hybrid_property[_TE]: return self._set(fget=fget) def setter(self, fset: _HybridSetterType[_TE]) -> hybrid_property[_TE]: return self._set(fset=fset) def deleter( self, fdel: _HybridDeleterType[_TE] ) -> hybrid_property[_TE]: return self._set(fdel=fdel) def expression( self, expr: _HybridExprCallableType[_TE] ) -> hybrid_property[_TE]: return self._set(expr=expr) def comparator( self, comparator: _HybridComparatorCallableType[_TE] ) -> hybrid_property[_TE]: return self._set(custom_comparator=comparator) def update_expression( self, meth: _HybridUpdaterType[_TE] ) -> hybrid_property[_TE]: return self._set(update_expr=meth) def bulk_dml( self, meth: _HybridBulkDMLType[_TE] ) -> hybrid_property[_TE]: return self._set(bulk_dml_setter=meth) @property def inplace(self) -> _InPlace[_T]: """Return the inplace mutator for this :class:`.hybrid_property`. This is to allow in-place mutation of the hybrid, allowing the first hybrid method of a certain name to be reused in order to add more methods without having to name those methods the same, e.g.:: class Interval(Base): # ... @hybrid_property def radius(self) -> float: return abs(self.length) / 2 @radius.inplace.setter def _radius_setter(self, value: float) -> None: self.length = value * 2 @radius.inplace.expression def _radius_expression(cls) -> ColumnElement[float]: return type_coerce(func.abs(cls.length) / 2, Float) .. versionadded:: 2.0.4 .. seealso:: :ref:`hybrid_pep484_naming` """ return hybrid_property._InPlace(self) def getter(self, fget: _HybridGetterType[_T]) -> hybrid_property[_T]: """Provide a modifying decorator that defines a getter method.""" return self._copy(fget=fget) def setter(self, fset: _HybridSetterType[_T]) -> hybrid_property[_T]: """Provide a modifying decorator that defines a setter method.""" return self._copy(fset=fset) def deleter(self, fdel: _HybridDeleterType[_T]) -> hybrid_property[_T]: """Provide a modifying decorator that defines a deletion method.""" return self._copy(fdel=fdel) def expression( self, expr: _HybridExprCallableType[_T] ) -> hybrid_property[_T]: """Provide a modifying decorator that defines a SQL-expression producing method. When a hybrid is invoked at the class level, the SQL expression given here is wrapped inside of a specialized :class:`.QueryableAttribute`, which is the same kind of object used by the ORM to represent other mapped attributes. The reason for this is so that other class-level attributes such as docstrings and a reference to the hybrid itself may be maintained within the structure that's returned, without any modifications to the original SQL expression passed in. .. note:: When referring to a hybrid property from an owning class (e.g. ``SomeClass.some_hybrid``), an instance of :class:`.QueryableAttribute` is returned, representing the expression or comparator object as well as this hybrid object. However, that object itself has accessors called ``expression`` and ``comparator``; so when attempting to override these decorators on a subclass, it may be necessary to qualify it using the :attr:`.hybrid_property.overrides` modifier first. See that modifier for details. .. seealso:: :ref:`hybrid_distinct_expression` """ return self._copy(expr=expr) def comparator( self, comparator: _HybridComparatorCallableType[_T] ) -> hybrid_property[_T]: """Provide a modifying decorator that defines a custom comparator producing method. The return value of the decorated method should be an instance of :class:`~.hybrid.Comparator`. .. note:: The :meth:`.hybrid_property.comparator` decorator **replaces** the use of the :meth:`.hybrid_property.expression` decorator. They cannot be used together. When a hybrid is invoked at the class level, the :class:`~.hybrid.Comparator` object given here is wrapped inside of a specialized :class:`.QueryableAttribute`, which is the same kind of object used by the ORM to represent other mapped attributes. The reason for this is so that other class-level attributes such as docstrings and a reference to the hybrid itself may be maintained within the structure that's returned, without any modifications to the original comparator object passed in. .. note:: When referring to a hybrid property from an owning class (e.g. ``SomeClass.some_hybrid``), an instance of :class:`.QueryableAttribute` is returned, representing the expression or comparator object as this hybrid object. However, that object itself has accessors called ``expression`` and ``comparator``; so when attempting to override these decorators on a subclass, it may be necessary to qualify it using the :attr:`.hybrid_property.overrides` modifier first. See that modifier for details. """ return self._copy(custom_comparator=comparator) def update_expression( self, meth: _HybridUpdaterType[_T] ) -> hybrid_property[_T]: """Provide a modifying decorator that defines an UPDATE tuple producing method. The method accepts a single value, which is the value to be rendered into the SET clause of an UPDATE statement. The method should then process this value into individual column expressions that fit into the ultimate SET clause, and return them as a sequence of 2-tuples. Each tuple contains a column expression as the key and a value to be rendered. E.g.:: class Person(Base): # ... first_name = Column(String) last_name = Column(String) @hybrid_property def fullname(self): return first_name + " " + last_name @fullname.update_expression def fullname(cls, value): fname, lname = value.split(" ", 1) return [(cls.first_name, fname), (cls.last_name, lname)] """ return self._copy(update_expr=meth) def bulk_dml(self, meth: _HybridBulkDMLType[_T]) -> hybrid_property[_T]: """Define a setter for bulk dml. .. versionadded:: 2.1 """ return self._copy(bulk_dml=meth) @util.memoized_property def _expr_comparator( self, ) -> Callable[[Any], _HybridClassLevelAccessor[_T]]: if self.custom_comparator is not None: return self._get_comparator(self.custom_comparator) elif self.expr is not None: return self._get_expr(self.expr) else: return self._get_expr(cast(_HybridExprCallableType[_T], self.fget)) def _get_expr( self, expr: _HybridExprCallableType[_T] ) -> Callable[[Any], _HybridClassLevelAccessor[_T]]: def _expr(cls: Any) -> ExprComparator[_T]: return ExprComparator(cls, expr(cls), self) util.update_wrapper(_expr, expr) return self._get_comparator(_expr) def _get_comparator( self, comparator: Any ) -> Callable[[Any], _HybridClassLevelAccessor[_T]]: proxy_attr = attributes._create_proxied_attribute(self) def expr_comparator( owner: Type[object], ) -> _HybridClassLevelAccessor[_T]: # because this is the descriptor protocol, we don't really know # what our attribute name is. so search for it through the # MRO. for lookup in owner.__mro__: if self.__name__ in lookup.__dict__: if lookup.__dict__[self.__name__] is self: name = self.__name__ break else: name = attributes._UNKNOWN_ATTR_KEY # type: ignore[assignment,unused-ignore] # noqa: E501 return cast( "_HybridClassLevelAccessor[_T]", proxy_attr( owner, name, self, comparator(owner), doc=comparator.__doc__ or self.__doc__, ), ) return expr_comparator class Comparator(interfaces.PropComparator[_T]): """A helper class that allows easy construction of custom :class:`~.orm.interfaces.PropComparator` classes for usage with hybrids.""" def __init__( self, expression: Union[_HasClauseElement[_T], SQLColumnExpression[_T]] ): self.expression = expression def __clause_element__(self) -> roles.ColumnsClauseRole: expr = self.expression if is_has_clause_element(expr): ret_expr = expr.__clause_element__() else: if TYPE_CHECKING: assert isinstance(expr, ColumnElement) ret_expr = expr if TYPE_CHECKING: # see test_hybrid->test_expression_isnt_clause_element # that exercises the usual place this is caught if not # true assert isinstance(ret_expr, ColumnElement) return ret_expr @util.non_memoized_property def property(self) -> interfaces.MapperProperty[_T]: raise NotImplementedError() def adapt_to_entity( self, adapt_to_entity: AliasedInsp[Any] ) -> Comparator[_T]: # interesting.... return self class ExprComparator(Comparator[_T]): def __init__( self, cls: Type[Any], expression: Union[_HasClauseElement[_T], SQLColumnExpression[_T]], hybrid: hybrid_property[_T], ): self.cls = cls self.expression = expression self.hybrid = hybrid def __getattr__(self, key: str) -> Any: return getattr(self.expression, key) @util.ro_non_memoized_property def info(self) -> _InfoType: return self.hybrid.info def _bulk_update_tuples( self, value: Any, ) -> Sequence[Tuple[_DMLColumnArgument, Any]]: if isinstance(self.expression, attributes.QueryableAttribute): return self.expression._bulk_update_tuples(value) elif self.hybrid.update_expr is not None: return self.hybrid.update_expr(self.cls, value) else: return [(self.expression, value)] def _bulk_dml_setter(self, key: str) -> Optional[Callable[..., Any]]: """return a callable that will process a bulk INSERT value""" meth = None def prop(mapping: MutableMapping[str, Any]) -> None: nonlocal meth value = mapping[key] if meth is None: if self.hybrid.bulk_dml_setter is None: raise exc.InvalidRequestError( "Can't evaluate bulk DML statement; please " "supply a bulk_dml decorated function" ) meth = self.hybrid.bulk_dml_setter meth(self.cls, mapping, value) return prop @util.non_memoized_property def property(self) -> MapperProperty[_T]: # this accessor is not normally used, however is accessed by things # like ORM synonyms if the hybrid is used in this context; the # .property attribute is not necessarily accessible return self.expression.property # type: ignore[no-any-return, union-attr] # noqa: E501 def operate( self, op: OperatorType, *other: Any, **kwargs: Any ) -> ColumnElement[Any]: return op(self.expression, *other, **kwargs) def reverse_operate( self, op: OperatorType, other: Any, **kwargs: Any ) -> ColumnElement[Any]: return op(other, self.expression, **kwargs) # type: ignore[no-any-return] # noqa: E501