Commit 0a261217 authored by Sergey Fedoseev's avatar Sergey Fedoseev Committed by Claude Paroz
Browse files

Refs #25629 -- Added `arity` class attribute to `Func` expressions

parent 03c6ad7a

django/db/models/expressions.py

+10 −0
Original line number Diff line number Diff line
@@ -482,8 +482,18 @@ class Func(Expression): 
    function = None

    template = '%(function)s(%(expressions)s)'

    arg_joiner = ', '

    arity = None  # The number of arguments the function accepts.



    def __init__(self, *expressions, **extra):

        if self.arity is not None and len(expressions) != self.arity:

            raise TypeError(

                "'%s' takes exactly %s %s (%s given)" % (

                    self.__class__.__name__,

                    self.arity,

                    "argument" if self.arity == 1 else "arguments",

                    len(expressions),

                )

            )

        output_field = extra.pop('output_field', None)

        super(Func, self).__init__(output_field=output_field)

        self.source_expressions = self._parse_expressions(*expressions)

django/db/models/functions.py

+0 −6
Original line number Diff line number Diff line
@@ -145,9 +145,6 @@ class Lower(Transform): 
    function = 'LOWER'

    lookup_name = 'lower'



    def __init__(self, expression, **extra):

        super(Lower, self).__init__(expression, **extra)





class Now(Func):

    template = 'CURRENT_TIMESTAMP'
@@ -197,6 +194,3 @@ class Substr(Func): 
class Upper(Transform):

    function = 'UPPER'

    lookup_name = 'upper'
 


    def __init__(self, expression, **extra):

        super(Upper, self).__init__(expression, **extra)

django/db/models/lookups.py

+1 −4
Original line number Diff line number Diff line
@@ -123,10 +123,7 @@ class Transform(RegisterLookupMixin, Func): 
    first examine self and then check output_field.

    """

    bilateral = False



    def __init__(self, expression, **extra):

        # Restrict Transform to allow only a single expression.

        super(Transform, self).__init__(expression, **extra)

    arity = 1



    @property

    def lhs(self):

docs/ref/models/expressions.txt

+9 −0
Original line number Diff line number Diff line
@@ -252,6 +252,15 @@ The ``Func`` API is as follows: 
        A class attribute that denotes the character used to join the list of

        ``expressions`` together. Defaults to ``', '``.



    .. attribute:: arity



        .. versionadded:: 1.10



        A class attribute that denotes the number of arguments the function

        accepts. If this attribute is set and the function is called with a

        different number of expressions, ``TypeError`` will be raised. Defaults

        to ``None``.



The ``*expressions`` argument is a list of positional expressions that the

function will be applied to. The expressions will be converted to strings,

joined together with ``arg_joiner``, and then interpolated into the ``template``

docs/releases/1.10.txt

+4 −0
Original line number Diff line number Diff line
@@ -175,6 +175,10 @@ Models 
  accessible as a descriptor on the proxied model class and may be referenced in

  queryset filtering.



* The :attr:`~django.db.models.Func.arity` class attribute is added to

  :class:`~django.db.models.Func`. This attribute can be used to set the number

  of arguments the function accepts.



Requests and Responses

^^^^^^^^^^^^^^^^^^^^^^