Fixed #24716 -- Deprecated Field._get_val_from_obj()

The method duplicates the functionality of Field.value_from_object()
and has the additional downside of being a privately named public
API method.

django/contrib/gis/serializers/geojson.py

@@ -60,7 +60,7 @@ class Serializer(JSONSerializer):
 
     def handle_field(self, obj, field):
         if field.name == self.geometry_field:
-            self._geometry = field._get_val_from_obj(obj)
+            self._geometry = field.value_from_object(obj)
         else:
             super(Serializer, self).handle_field(obj, field)
 

django/contrib/postgres/fields/array.py

@@ -90,7 +90,7 @@ class ArrayField(Field):
 
     def value_to_string(self, obj):
         values = []
-        vals = self._get_val_from_obj(obj)
+        vals = self.value_from_object(obj)
         base_field = self.base_field
 
         for val in vals:

django/contrib/postgres/fields/hstore.py

@@ -42,8 +42,7 @@ class HStoreField(Field):
         return value
 
     def value_to_string(self, obj):
-        value = self._get_val_from_obj(obj)
-        return json.dumps(value)
+        return json.dumps(self.value_from_object(obj))
 
     def formfield(self, **kwargs):
         defaults = {

django/contrib/postgres/fields/jsonb.py

@@ -50,7 +50,7 @@ class JSONField(Field):
             )
 
     def value_to_string(self, obj):
-        value = self._get_val_from_obj(obj)
+        value = self.value_from_object(obj)
         return value
 
     def formfield(self, **kwargs):

django/contrib/postgres/fields/ranges.py

@@ -43,7 +43,7 @@ class RangeField(models.Field):
         self.base_field.set_attributes_from_name(name)
 
     def value_to_string(self, obj):
-        value = self._get_val_from_obj(obj)
+        value = self.value_from_object(obj)
         if value is None:
             return None
         if value.isempty:

django/core/serializers/python.py

@@ -45,7 +45,7 @@ class Serializer(base.Serializer):
         return data
 
     def handle_field(self, obj, field):
-        value = field._get_val_from_obj(obj)
+        value = field.value_from_object(obj)
         # Protected types (i.e., primitives like None, numbers, dates,
         # and Decimals) are passed through as is. All other values are
         # converted to string first.

django/db/models/fields/__init__.py

@@ -29,7 +29,9 @@ from django.utils.datastructures import DictWrapper
 from django.utils.dateparse import (
     parse_date, parse_datetime, parse_duration, parse_time,
 )
-from django.utils.deprecation import RemovedInDjango20Warning
+from django.utils.deprecation import (
+    RemovedInDjango20Warning, warn_about_renamed_method,
+)
 from django.utils.duration import duration_string
 from django.utils.encoding import (
     force_bytes, force_text, python_2_unicode_compatible, smart_text,
@@ -832,6 +834,10 @@ class Field(RegisterLookupMixin):
         first_choice = blank_choice if include_blank else []
         return first_choice + list(self.flatchoices)
 
+    @warn_about_renamed_method(
+        'Field', '_get_val_from_obj', 'value_from_object',
+        RemovedInDjango20Warning
+    )
     def _get_val_from_obj(self, obj):
         if obj is not None:
             return getattr(obj, self.attname)
@@ -843,7 +849,7 @@ class Field(RegisterLookupMixin):
         Returns a string value of this field from the passed obj.
         This is used by the serialization framework.
         """
-        return smart_text(self._get_val_from_obj(obj))
+        return smart_text(self.value_from_object(obj))
 
     def _get_flatchoices(self):
         """Flattened version of choices tuple."""
@@ -1298,7 +1304,7 @@ class DateField(DateTimeCheckMixin, Field):
         return connection.ops.adapt_datefield_value(value)
 
     def value_to_string(self, obj):
-        val = self._get_val_from_obj(obj)
+        val = self.value_from_object(obj)
         return '' if val is None else val.isoformat()
 
     def formfield(self, **kwargs):
@@ -1458,7 +1464,7 @@ class DateTimeField(DateField):
         return connection.ops.adapt_datetimefield_value(value)
 
     def value_to_string(self, obj):
-        val = self._get_val_from_obj(obj)
+        val = self.value_from_object(obj)
         return '' if val is None else val.isoformat()
 
     def formfield(self, **kwargs):
@@ -1680,7 +1686,7 @@ class DurationField(Field):
         return converters + super(DurationField, self).get_db_converters(connection)
 
     def value_to_string(self, obj):
-        val = self._get_val_from_obj(obj)
+        val = self.value_from_object(obj)
         return '' if val is None else duration_string(val)
 
     def formfield(self, **kwargs):
@@ -2288,7 +2294,7 @@ class TimeField(DateTimeCheckMixin, Field):
         return connection.ops.adapt_timefield_value(value)
 
     def value_to_string(self, obj):
-        val = self._get_val_from_obj(obj)
+        val = self.value_from_object(obj)
         return '' if val is None else val.isoformat()
 
     def formfield(self, **kwargs):
@@ -2355,7 +2361,7 @@ class BinaryField(Field):
 
     def value_to_string(self, obj):
         """Binary data is serialized as base64"""
-        return b64encode(force_bytes(self._get_val_from_obj(obj))).decode('ascii')
+        return b64encode(force_bytes(self.value_from_object(obj))).decode('ascii')
 
     def to_python(self, value):
         # If it's a string, it should be base64-encoded data

docs/howto/custom-model-fields.txt

@@ -705,15 +705,16 @@ Converting field data for serialization
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 To customize how the values are serialized by a serializer, you can override
-:meth:`~Field.value_to_string`. Calling ``Field._get_val_from_obj(obj)`` is the
-best way to get the value serialized. For example, since our ``HandField`` uses
-strings for its data storage anyway, we can reuse some existing conversion code::
+:meth:`~Field.value_to_string`. Using ``value_from_object()`` is the best way
+to get the field's value prior to serialization. For example, since our
+``HandField`` uses strings for its data storage anyway, we can reuse some
+existing conversion code::
 
     class HandField(models.Field):
         # ...
 
         def value_to_string(self, obj):
-            value = self._get_val_from_obj(obj)
+            value = self.value_from_object(obj)
             return self.get_prep_value(value)
 
 Some general advice

docs/internals/deprecation.txt

@@ -79,6 +79,9 @@ details on these changes.
 * Support for setting a URL instance namespace without an application
   namespace will be removed.
 
+* ``Field._get_val_from_obj()`` will be removed in favor of
+  ``Field.value_from_object()``.
+
 .. _deprecation-removed-in-1.10:
 
 1.10

docs/releases/1.9.txt

@@ -1001,6 +1001,9 @@ Miscellaneous
 * :class:`~django.core.signing.Signer` now issues a warning if an invalid
   separator is used. This will become an exception in Django 1.10.
 
+* ``django.db.models.Field._get_val_from_obj()`` is deprecated in favor of
+  ``Field.value_from_object()``.
+
 .. removed-features-1.9:
 
 Features removed in 1.9

tests/serializers/models.py

@@ -141,7 +141,7 @@ class TeamField(models.CharField):
         return Team(value)
 
     def value_to_string(self, obj):
-        return self._get_val_from_obj(obj).to_string()
+        return self.value_from_object(obj).to_string()
 
     def deconstruct(self):
         name, path, args, kwargs = super(TeamField, self).deconstruct()