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Module « sqlalchemy »

Classe « ARRAY »

Informations générales

Héritage

builtins.object
    Generic
builtins.object
    Visitable
        TypeEngine
builtins.object
    TypeEngineMixin
        Concatenable
builtins.object
    TypeEngineMixin
        Indexable
builtins.object
    EventTarget
        SchemaEventTarget
            ARRAY

Définition

class ARRAY(SchemaEventTarget, Indexable, Concatenable, TypeEngine):

help(ARRAY)

Represent a SQL Array type.

.. note::  This type serves as the basis for all ARRAY operations.
   However, currently **only the PostgreSQL backend has support for SQL
   arrays in SQLAlchemy**. It is recommended to use the PostgreSQL-specific
   :class:`sqlalchemy.dialects.postgresql.ARRAY` type directly when using
   ARRAY types with PostgreSQL, as it provides additional operators
   specific to that backend.

:class:`_types.ARRAY` is part of the Core in support of various SQL
standard functions such as :class:`_functions.array_agg`
which explicitly involve
arrays; however, with the exception of the PostgreSQL backend and possibly
some third-party dialects, no other SQLAlchemy built-in dialect has support
for this type.

An :class:`_types.ARRAY` type is constructed given the "type"
of element::

    mytable = Table("mytable", metadata, Column("data", ARRAY(Integer)))

The above type represents an N-dimensional array,
meaning a supporting backend such as PostgreSQL will interpret values
with any number of dimensions automatically.   To produce an INSERT
construct that passes in a 1-dimensional array of integers::

    connection.execute(mytable.insert(), {"data": [1, 2, 3]})

The :class:`_types.ARRAY` type can be constructed given a fixed number
of dimensions::

    mytable = Table(
        "mytable", metadata, Column("data", ARRAY(Integer, dimensions=2))
    )

Sending a number of dimensions is optional, but recommended if the
datatype is to represent arrays of more than one dimension.  This number
is used:

* When emitting the type declaration itself to the database, e.g.
  ``INTEGER[][]``

* When translating Python values to database values, and vice versa, e.g.
  an ARRAY of :class:`.Unicode` objects uses this number to efficiently
  access the string values inside of array structures without resorting
  to per-row type inspection

* When used with the Python ``getitem`` accessor, the number of dimensions
  serves to define the kind of type that the ``[]`` operator should
  return, e.g. for an ARRAY of INTEGER with two dimensions::

      >>> expr = table.c.column[5]  # returns ARRAY(Integer, dimensions=1)
      >>> expr = expr[6]  # returns Integer

For 1-dimensional arrays, an :class:`_types.ARRAY` instance with no
dimension parameter will generally assume single-dimensional behaviors.

SQL expressions of type :class:`_types.ARRAY` have support for "index" and
"slice" behavior.  The ``[]`` operator produces expression
constructs which will produce the appropriate SQL, both for
SELECT statements::

    select(mytable.c.data[5], mytable.c.data[2:7])

as well as UPDATE statements when the :meth:`_expression.Update.values`
method is used::

    mytable.update().values(
        {mytable.c.data[5]: 7, mytable.c.data[2:7]: [1, 2, 3]}
    )

Indexed access is one-based by default;
for zero-based index conversion, set :paramref:`_types.ARRAY.zero_indexes`.

The :class:`_types.ARRAY` type also provides for the operators
:meth:`.types.ARRAY.Comparator.any` and
:meth:`.types.ARRAY.Comparator.all`. The PostgreSQL-specific version of
:class:`_types.ARRAY` also provides additional operators.

.. container:: topic

    **Detecting Changes in ARRAY columns when using the ORM**

    The :class:`_sqltypes.ARRAY` type, when used with the SQLAlchemy ORM,
    does not detect in-place mutations to the array. In order to detect
    these, the :mod:`sqlalchemy.ext.mutable` extension must be used, using
    the :class:`.MutableList` class::

        from sqlalchemy import ARRAY
        from sqlalchemy.ext.mutable import MutableList


        class SomeOrmClass(Base):
            # ...

            data = Column(MutableList.as_mutable(ARRAY(Integer)))

    This extension will allow "in-place" changes such to the array
    such as ``.append()`` to produce events which will be detected by the
    unit of work.  Note that changes to elements **inside** the array,
    including subarrays that are mutated in place, are **not** detected.

    Alternatively, assigning a new array value to an ORM element that
    replaces the old one will always trigger a change event.

.. seealso::

    :class:`sqlalchemy.dialects.postgresql.ARRAY`

Constructeur(s)

Signature du constructeur	Description
__init__(self, item_type: '_TypeEngineArgument[Any]', as_tuple: 'bool' = False, dimensions: 'Optional[int]' = None, zero_indexes: 'bool' = False)	Construct an :class:`_types.ARRAY`. [extrait de __init__.__doc__]

Attributs statiques hérités de la classe TypeEngine

hashable

Liste des opérateurs

Opérateurs hérités de la classe object

__eq__, __ge__, __gt__, __le__, __lt__, __ne__

Méthodes héritées de la classe TypeEngine

__repr__, __str__, __subclasshook__, adapt, as_generic, bind_expression, bind_processor, coerce_compared_value, column_expression, compile, copy, copy_value, dialect_impl, evaluates_none, get_dbapi_type, result_processor, with_variant

Méthodes héritées de la classe Generic

__class_getitem__, __init_subclass__

Méthodes héritées de la classe Visitable

__class_getitem__, __init_subclass__

Méthodes héritées de la classe object

__delattr__, __dir__, __format__, __getattribute__, __getstate__, __hash__, __reduce__, __reduce_ex__, __setattr__, __sizeof__

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