Min/MaxValue/LengthValidator now defer the message formatting and able to handle new string format.

rest_framework/compat.py

@@ -11,6 +11,8 @@ from django.conf import settings
 from django.db import connection, transaction
 from django.utils import six
 from django.views.generic import View
+from django.core.exceptions import ValidationError
+
 
 try:
     import importlib  # Available in Python 3.1+
@@ -109,39 +111,43 @@ def get_model_name(model_cls):
         return model_cls._meta.module_name
 
 
-# MinValueValidator, MaxValueValidator et al. only accept `message` in 1.8+
+from django.core.validators import MinValueValidator
-if django.VERSION >= (1, 8):
+from django.core.validators import MaxValueValidator
-    from django.core.validators import MinValueValidator, MaxValueValidator
+from django.core.validators import MinLengthValidator
-    from django.core.validators import MinLengthValidator, MaxLengthValidator
+from django.core.validators import MaxLengthValidator
-else:
-    from django.core.validators import MinValueValidator as DjangoMinValueValidator
-    from django.core.validators import MaxValueValidator as DjangoMaxValueValidator
-    from django.core.validators import MinLengthValidator as DjangoMinLengthValidator
-    from django.core.validators import MaxLengthValidator as DjangoMaxLengthValidator
 
 
-    class MinValueValidator(DjangoMinValueValidator):
+class CustomValidatorMessage(object):
-        def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs):
-            self.message = kwargs.pop('message', self.message)
+        self.message = kwargs.pop('message', self.message)
-            super(MinValueValidator, self).__init__(*args, **kwargs)
+        self.format = kwargs.pop('string_format', '%')
+        super(CustomValidatorMessage, self).__init__(*args, **kwargs)
+
+    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):
+            message = self.message
+            if self.format == '{':
+                args = {self.code: self.limit_value}
+                message = message.format(**args)
+            raise ValidationError(message, code=self.code, params=params)
 
 
-    class MaxValueValidator(DjangoMaxValueValidator):
+class MinValueValidator(CustomValidatorMessage, MinValueValidator):
-        def __init__(self, *args, **kwargs):
+    pass
-            self.message = kwargs.pop('message', self.message)
-            super(MaxValueValidator, self).__init__(*args, **kwargs)
 
 
-    class MinLengthValidator(DjangoMinLengthValidator):
+class MaxValueValidator(CustomValidatorMessage, MaxValueValidator):
-        def __init__(self, *args, **kwargs):
+    pass
-            self.message = kwargs.pop('message', self.message)
-            super(MinLengthValidator, self).__init__(*args, **kwargs)
 
 
-    class MaxLengthValidator(DjangoMaxLengthValidator):
+class MinLengthValidator(CustomValidatorMessage, MinLengthValidator):
-        def __init__(self, *args, **kwargs):
+    pass
-            self.message = kwargs.pop('message', self.message)
+
-            super(MaxLengthValidator, self).__init__(*args, **kwargs)
+
+class MaxLengthValidator(CustomValidatorMessage, MaxLengthValidator):
+    pass
 
 
 # URLValidator only accepts `message` in 1.6+

rest_framework/fields.py

@@ -675,9 +675,11 @@ class CharField(Field):
         self.min_length = kwargs.pop('min_length', None)
         super(CharField, self).__init__(**kwargs)
         if self.max_length is not None:
-            self.validators.append(MaxLengthValidator(self.max_length))
+            message = self.error_messages['max_length']
+            self.validators.append(MaxLengthValidator(self.max_length, message=message, string_format='{'))
         if self.min_length is not None:
-            self.validators.append(MinLengthValidator(self.min_length))
+            message = self.error_messages['min_length']
+            self.validators.append(MinLengthValidator(self.min_length, message=message, string_format='{'))
 
     def run_validation(self, data=empty):
         # Test for the empty string here so that it does not get validated,
@@ -818,9 +820,11 @@ class IntegerField(Field):
         self.min_value = kwargs.pop('min_value', None)
         super(IntegerField, self).__init__(**kwargs)
         if self.max_value is not None:
-            self.validators.append(MaxValueValidator(self.max_value))
+            message = self.error_messages['max_value']
+            self.validators.append(MaxValueValidator(self.max_value, message=message, string_format='{'))
         if self.min_value is not None:
-            self.validators.append(MinValueValidator(self.min_value))
+            message = self.error_messages['min_value']
+            self.validators.append(MinValueValidator(self.min_value, message=message, string_format='{'))
 
     def to_internal_value(self, data):
         if isinstance(data, six.text_type) and len(data) > self.MAX_STRING_LENGTH:
@@ -850,9 +854,11 @@ class FloatField(Field):
         self.min_value = kwargs.pop('min_value', None)
         super(FloatField, self).__init__(**kwargs)
         if self.max_value is not None:
-            self.validators.append(MaxValueValidator(self.max_value))
+            message = self.error_messages['max_value']
+            self.validators.append(MaxValueValidator(self.max_value, message=message, string_format='{'))
         if self.min_value is not None:
-            self.validators.append(MinValueValidator(self.min_value))
+            message = self.error_messages['min_value']
+            self.validators.append(MinValueValidator(self.min_value, message=message, string_format='{'))
 
     def to_internal_value(self, data):
         if isinstance(data, six.text_type) and len(data) > self.MAX_STRING_LENGTH:
@@ -897,9 +903,11 @@ class DecimalField(Field):
         super(DecimalField, self).__init__(**kwargs)
 
         if self.max_value is not None:
-            self.validators.append(MaxValueValidator(self.max_value))
+            message = self.error_messages['max_value']
+            self.validators.append(MaxValueValidator(self.max_value, message=message, string_format='{'))
         if self.min_value is not None:
-            self.validators.append(MinValueValidator(self.min_value))
+            message = self.error_messages['min_value']
+            self.validators.append(MinValueValidator(self.min_value, message=message, string_format='{'))
 
     def to_internal_value(self, data):
         """
@@ -1598,7 +1606,8 @@ class ModelField(Field):
         max_length = kwargs.pop('max_length', None)
         super(ModelField, self).__init__(**kwargs)
         if max_length is not None:
-            self.validators.append(MaxLengthValidator(max_length))
+            message = self.error_messages['max_length']
+            self.validators.append(MaxLengthValidator(max_length, message=message, string_format='{'))
 
     def to_internal_value(self, data):
         rel = getattr(self.model_field, 'rel', None)