Fixed #29860 -- Allowed BaseValidator to accept a callable limit_value.

django/core/validators.py

@@ -317,8 +317,9 @@ class BaseValidator:
 
     def __call__(self, value):
         cleaned = self.clean(value)
-        params = {'limit_value': self.limit_value, 'show_value': cleaned, 'value': value}
-        if self.compare(cleaned, self.limit_value):
+        limit_value = self.limit_value() if callable(self.limit_value) else self.limit_value
+        params = {'limit_value': limit_value, 'show_value': cleaned, 'value': value}
+        if self.compare(cleaned, limit_value):
             raise ValidationError(self.message, code=self.code, params=params)
 
     def __eq__(self, other):

docs/ref/validators.txt

@@ -236,7 +236,12 @@ to, or in lieu of custom ``field.clean()`` methods.
 .. class:: MaxValueValidator(limit_value, message=None)
 
     Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
-    ``'max_value'`` if ``value`` is greater than ``limit_value``.
+    ``'max_value'`` if ``value`` is greater than ``limit_value``, which may be
+    a callable.
+
+    .. versionchanged:: 2.2
+
+        ``limit_value`` can now be a callable.
 
 ``MinValueValidator``
 ---------------------
@@ -244,7 +249,12 @@ to, or in lieu of custom ``field.clean()`` methods.
 .. class:: MinValueValidator(limit_value, message=None)
 
     Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
-    ``'min_value'`` if ``value`` is less than ``limit_value``.
+    ``'min_value'`` if ``value`` is less than ``limit_value``, which may be a
+    callable.
+
+    .. versionchanged:: 2.2
+
+        ``limit_value`` can now be a callable.
 
 ``MaxLengthValidator``
 ----------------------
@@ -252,7 +262,12 @@ to, or in lieu of custom ``field.clean()`` methods.
 .. class:: MaxLengthValidator(limit_value, message=None)
 
     Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
-    ``'max_length'`` if the length of ``value`` is greater than ``limit_value``.
+    ``'max_length'`` if the length of ``value`` is greater than
+    ``limit_value``, which may be a callable.
+
+    .. versionchanged:: 2.2
+
+        ``limit_value`` can now be a callable.
 
 ``MinLengthValidator``
 ----------------------
@@ -260,7 +275,12 @@ to, or in lieu of custom ``field.clean()`` methods.
 .. class:: MinLengthValidator(limit_value, message=None)
 
     Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
-    ``'min_length'`` if the length of ``value`` is less than ``limit_value``.
+    ``'min_length'`` if the length of ``value`` is less than ``limit_value``,
+    which may be a callable.
+
+    .. versionchanged:: 2.2
+
+        ``limit_value`` can now be a callable.
 
 ``DecimalValidator``
 --------------------

docs/releases/2.2.txt

@@ -259,7 +259,9 @@ URLs
 Validators
 ~~~~~~~~~~
 
-* ...
+* :class:`.MaxValueValidator`, :class:`.MinValueValidator`,
+  :class:`.MinLengthValidator`, and :class:`.MaxLengthValidator` now accept
+  a callable ``limit_value``.
 
 .. _backwards-incompatible-2.2:
 

tests/validators/tests.py

@@ -203,6 +203,10 @@ TEST_DATA = [
     (MinValueValidator(0), -1, ValidationError),
     (MinValueValidator(NOW), NOW - timedelta(days=1), ValidationError),
 
+    # limit_value may be a callable.
+    (MinValueValidator(lambda: 1), 0, ValidationError),
+    (MinValueValidator(lambda: 1), 1, None),
+
     (MaxLengthValidator(10), '', None),
     (MaxLengthValidator(10), 10 * 'x', None),