documentation for Base64ImageField and test for blank case

docs/api-guide/fields.md

@@ -299,6 +299,7 @@ Requires either the `Pillow` package or `PIL` package.  The `Pillow` package is
 
 Signature and validation is the same as with `FileField`.
 
+
 ---
 
 **Note:** `FileFields` and `ImageFields` are only suitable for use with MultiPartParser, since e.g. json doesn't support file uploads.
@@ -306,6 +307,32 @@ Django's regular [FILE_UPLOAD_HANDLERS] are used for handling uploaded files.
 
 ---
 
+
+## Base64ImageField
+
+An image representation for Base64ImageField
+
+Intherited by `ImageField`
+
+**Signature:** `Base64ImageField()`
+
+ - It takes a base64 image as a string.
+ - a base64 image:  `data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7`
+ - Base64ImageField accepts only the part after base64, `R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7`
+
+ **Example:**
+
+    #serializer
+    class UploadedBase64ImageSerializer(serializers.Serializer):
+        file = serializers.Base64ImageField(required=False)
+        created = serializers.DateTimeField()
+
+    #use the serializer
+    file = 'R0lGODlhAQABAIAAAP///////yH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=='
+    serializer = UploadedBase64ImageSerializer(data={'created': now, 'file': file})
+
+
+
 # Custom fields
 
 If you want to create a custom field, you'll probably want to override either one or both of the `.to_native()` and `.from_native()` methods.  These two methods are used to convert between the initial datatype, and a primitive, serializable datatype.  Primitive datatypes may be any of a number, string, date/time/datetime or None.  They may also be any list or dictionary like object that only contains other primitive objects.

rest_framework/fields.py

@@ -1062,6 +1062,9 @@ class Base64ImageField(ImageField):
     """
     def from_native(self, base64_data):
         # Check if this is a base64 string
+        if base64_data in validators.EMPTY_VALUES:
+            return None
+
         if isinstance(base64_data, basestring):
             # Try to decode the file. Return validation error if it fails.
             try:
@@ -1081,7 +1084,7 @@ class Base64ImageField(ImageField):
 
     def to_native(self, value):
         # Return url including domain name.
-        return ""
+        return value.name
 
     def get_file_extension(self, filename, decoded_file):
         extension = imghdr.what(filename, decoded_file)

rest_framework/tests/test_fields.py

@@ -1011,7 +1011,7 @@ class UploadedBase64Image(object):
 
 
 class UploadedBase64ImageSerializer(serializers.Serializer):
-    file = serializers.Base64ImageField()
+    file = serializers.Base64ImageField(required=False)
     created = serializers.DateTimeField()
 
     def restore_object(self, attrs, instance=None):
@@ -1025,6 +1025,9 @@ class UploadedBase64ImageSerializer(serializers.Serializer):
 class Base64ImageSerializerTests(TestCase):
 
     def test_create(self):
+        """
+        Test for creating Base64 image in the server side
+        """
         now = datetime.datetime.now()
         file = 'R0lGODlhAQABAIAAAP///////yH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=='
         serializer = UploadedBase64ImageSerializer(data={'created': now, 'file': file})
@@ -1033,24 +1036,25 @@ class Base64ImageSerializerTests(TestCase):
         self.assertEqual(serializer.object.created, uploaded_image.created)
         self.assertFalse(serializer.object is uploaded_image)
 
-
-    def test_creation_failure(self):
-        """
-        Passing file=None should result in an ValidationError
-        """
-        errmsg = 'This field is required.'
-        now = datetime.datetime.now()
-        serializer = UploadedBase64ImageSerializer(data={'created': now})
-        self.assertFalse(serializer.is_valid())
-        self.assertEqual(serializer.errors, {'file': [errmsg]})
-
     def test_validation_error_with_non_file(self):
         """
         Passing non-base64 should raise a validation error.
         """
         now = datetime.datetime.now()
         errmsg = "Please upload a valid image."
-
         serializer = UploadedBase64ImageSerializer(data={'created': now, 'file': 'abc'})
         self.assertFalse(serializer.is_valid())
-        self.assertEqual(serializer.errors, {'file': [errmsg]})
+        self.assertEqual(serializer.errors, {'file': [errmsg]})
+
+
+    def test_remove_with_empty_string(self):
+        """
+        Passing empty string as data should cause image to be removed
+        """
+        now = datetime.datetime.now()
+        file = 'R0lGODlhAQABAIAAAP///////yH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=='
+        uploaded_image = UploadedBase64Image(file=file, created=now)
+        serializer = UploadedBase64ImageSerializer(instance=uploaded_image, data={'created': now, 'file': ''})
+        self.assertTrue(serializer.is_valid())
+        self.assertEqual(serializer.object.created, uploaded_image.created)
+        self.assertIsNone(serializer.object.file)