[1.8.x] Update converters to take a consistent set of parameters.

As suggested by Anssi. This has the slightly strange side effect of
passing the expression to Expression.convert_value has the expression
passed back to it, but it allows more complex patterns of expressions.

Backport of 32d4db66b9 from master

django/contrib/gis/db/backends/oracle/operations.py

@@ -127,7 +127,7 @@ class OracleOperations(BaseSpatialOperations, DatabaseOperations):
             converters.append(self.convert_geometry)
         return converters
 
-    def convert_geometry(self, value, expression, context):
+    def convert_geometry(self, value, expression, connection, context):
         if value:
             value = Geometry(value)
             if 'transformed_srid' in context:

django/contrib/gis/db/backends/spatialite/operations.py

@@ -262,7 +262,7 @@ class SpatiaLiteOperations(BaseSpatialOperations, DatabaseOperations):
             converters.append(self.convert_geometry)
         return converters
 
-    def convert_geometry(self, value, expression, context):
+    def convert_geometry(self, value, expression, connection, context):
         if value:
             value = Geometry(value)
             if 'transformed_srid' in context:

django/contrib/gis/db/models/aggregates.py

@@ -29,7 +29,7 @@ class GeoAggregate(Aggregate):
             raise ValueError('Geospatial aggregates only allowed on geometry fields.')
         return c
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         return connection.ops.convert_geom(value, self.output_field)
 
 
@@ -44,7 +44,7 @@ class Extent(GeoAggregate):
     def __init__(self, expression, **extra):
         super(Extent, self).__init__(expression, output_field=ExtentField(), **extra)
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         return connection.ops.convert_extent(value, context.get('transformed_srid'))
 
 
@@ -55,7 +55,7 @@ class Extent3D(GeoAggregate):
     def __init__(self, expression, **extra):
         super(Extent3D, self).__init__(expression, output_field=ExtentField(), **extra)
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         return connection.ops.convert_extent3d(value, context.get('transformed_srid'))
 
 

django/contrib/gis/db/models/fields.py

@@ -219,7 +219,7 @@ class GeometryField(GeoSelectFormatMixin, Field):
         else:
             return geom
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         if value and not isinstance(value, Geometry):
             value = Geometry(value)
         return value

django/contrib/gis/db/models/sql/conversion.py

@@ -23,7 +23,7 @@ class AreaField(BaseField):
     def __init__(self, area_att):
         self.area_att = area_att
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         if value is not None:
             value = Area(**{self.area_att: value})
         return value
@@ -37,7 +37,7 @@ class DistanceField(BaseField):
     def __init__(self, distance_att):
         self.distance_att = distance_att
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         if value is not None:
             value = Distance(**{self.distance_att: value})
         return value
@@ -54,7 +54,7 @@ class GeomField(GeoSelectFormatMixin, BaseField):
     # Hacky marker for get_db_converters()
     geom_type = None
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         if value is not None:
             value = Geometry(value)
         return value
@@ -71,5 +71,5 @@ class GMLField(BaseField):
     def get_internal_type(self):
         return 'GMLField'
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         return value

django/db/backends/base/operations.py

@@ -519,7 +519,7 @@ class BaseDatabaseOperations(object):
         """
         return []
 
-    def convert_durationfield_value(self, value, expression, context):
+    def convert_durationfield_value(self, value, expression, connection, context):
         if value is not None:
             value = str(decimal.Decimal(value) / decimal.Decimal(1000000))
             value = parse_duration(value)

django/db/backends/mysql/operations.py

@@ -184,17 +184,17 @@ class DatabaseOperations(BaseDatabaseOperations):
             converters.append(self.convert_textfield_value)
         return converters
 
-    def convert_booleanfield_value(self, value, expression, context):
+    def convert_booleanfield_value(self, value, expression, connection, context):
         if value in (0, 1):
             value = bool(value)
         return value
 
-    def convert_uuidfield_value(self, value, expression, context):
+    def convert_uuidfield_value(self, value, expression, connection, context):
         if value is not None:
             value = uuid.UUID(value)
         return value
 
-    def convert_textfield_value(self, value, expression, context):
+    def convert_textfield_value(self, value, expression, connection, context):
         if value is not None:
             value = force_text(value)
         return value

django/db/backends/oracle/operations.py

@@ -172,7 +172,7 @@ WHEN (new.%(col_name)s IS NULL)
         converters.append(self.convert_empty_values)
         return converters
 
-    def convert_empty_values(self, value, expression, context):
+    def convert_empty_values(self, value, expression, connection, context):
         # Oracle stores empty strings as null. We need to undo this in
         # order to adhere to the Django convention of using the empty
         # string instead of null, but only if the field accepts the
@@ -184,17 +184,17 @@ WHEN (new.%(col_name)s IS NULL)
                 value = b''
         return value
 
-    def convert_textfield_value(self, value, expression, context):
+    def convert_textfield_value(self, value, expression, connection, context):
         if isinstance(value, Database.LOB):
             value = force_text(value.read())
         return value
 
-    def convert_binaryfield_value(self, value, expression, context):
+    def convert_binaryfield_value(self, value, expression, connection, context):
         if isinstance(value, Database.LOB):
             value = force_bytes(value.read())
         return value
 
-    def convert_booleanfield_value(self, value, expression, context):
+    def convert_booleanfield_value(self, value, expression, connection, context):
         if value in (1, 0):
             value = bool(value)
         return value
@@ -202,16 +202,16 @@ WHEN (new.%(col_name)s IS NULL)
     # cx_Oracle always returns datetime.datetime objects for
     # DATE and TIMESTAMP columns, but Django wants to see a
     # python datetime.date, .time, or .datetime.
-    def convert_datefield_value(self, value, expression, context):
+    def convert_datefield_value(self, value, expression, connection, context):
         if isinstance(value, Database.Timestamp):
             return value.date()
 
-    def convert_timefield_value(self, value, expression, context):
+    def convert_timefield_value(self, value, expression, connection, context):
         if isinstance(value, Database.Timestamp):
             value = value.time()
         return value
 
-    def convert_uuidfield_value(self, value, expression, context):
+    def convert_uuidfield_value(self, value, expression, connection, context):
         if value is not None:
             value = uuid.UUID(value)
         return value

django/db/backends/sqlite3/operations.py

@@ -153,25 +153,25 @@ class DatabaseOperations(BaseDatabaseOperations):
             converters.append(self.convert_uuidfield_value)
         return converters
 
-    def convert_decimalfield_value(self, value, expression, context):
+    def convert_decimalfield_value(self, value, expression, connection, context):
         return backend_utils.typecast_decimal(expression.output_field.format_number(value))
 
-    def convert_datefield_value(self, value, expression, context):
+    def convert_datefield_value(self, value, expression, connection, context):
         if value is not None and not isinstance(value, datetime.date):
             value = parse_date(value)
         return value
 
-    def convert_datetimefield_value(self, value, expression, context):
+    def convert_datetimefield_value(self, value, expression, connection, context):
         if value is not None and not isinstance(value, datetime.datetime):
             value = parse_datetime_with_timezone_support(value)
         return value
 
-    def convert_timefield_value(self, value, expression, context):
+    def convert_timefield_value(self, value, expression, connection, context):
         if value is not None and not isinstance(value, datetime.time):
             value = parse_time(value)
         return value
 
-    def convert_uuidfield_value(self, value, expression, context):
+    def convert_uuidfield_value(self, value, expression, connection, context):
         if value is not None:
             value = uuid.UUID(value)
         return value

django/db/models/aggregates.py

@@ -77,7 +77,7 @@ class Avg(Aggregate):
     def __init__(self, expression, **extra):
         super(Avg, self).__init__(expression, output_field=FloatField(), **extra)
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if value is None:
             return value
         return float(value)
@@ -101,7 +101,7 @@ class Count(Aggregate):
             'False' if self.extra['distinct'] == '' else 'True',
         )
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if value is None:
             return 0
         return int(value)
@@ -131,7 +131,7 @@ class StdDev(Aggregate):
             'False' if self.function == 'STDDEV_POP' else 'True',
         )
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if value is None:
             return value
         return float(value)
@@ -156,7 +156,7 @@ class Variance(Aggregate):
             'False' if self.function == 'VAR_POP' else 'True',
         )
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if value is None:
             return value
         return float(value)

django/db/models/expressions.py

@@ -252,7 +252,7 @@ class BaseExpression(object):
                         raise FieldError(
                             "Expression contains mixed types. You must set output_field")
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         """
         Expressions provide their own converters because users have the option
         of manually specifying the output_field which may be a different type
@@ -804,7 +804,7 @@ class Date(ExpressionNode):
         copy.lookup_type = self.lookup_type
         return copy
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if isinstance(value, datetime.datetime):
             value = value.date()
         return value
@@ -856,7 +856,7 @@ class DateTime(ExpressionNode):
         copy.tzname = self.tzname
         return copy
 
-    def convert_value(self, value, connection, context):
+    def convert_value(self, value, expression, connection, context):
         if settings.USE_TZ:
             if value is None:
                 raise ValueError(

django/db/models/fields/related.py

@@ -1991,7 +1991,7 @@ class ForeignKey(ForeignObject):
     def db_parameters(self, connection):
         return {"type": self.db_type(connection), "check": []}
 
-    def convert_empty_strings(self, value, connection, context):
+    def convert_empty_strings(self, value, expression, connection, context):
         if (not value) and isinstance(value, six.string_types):
             return None
         return value

django/db/models/sql/compiler.py

@@ -762,17 +762,15 @@ class SQLCompiler(object):
                 backend_converters = self.connection.ops.get_db_converters(expression)
                 field_converters = expression.get_db_converters(self.connection)
                 if backend_converters or field_converters:
-                    converters[i] = (backend_converters, field_converters, expression)
+                    converters[i] = (backend_converters + field_converters, expression)
         return converters
 
     def apply_converters(self, row, converters):
         row = list(row)
-        for pos, (backend_converters, field_converters, field) in converters.items():
+        for pos, (convs, expression) in converters.items():
             value = row[pos]
-            for converter in backend_converters:
-                value = converter(value, field, self.query.context)
-            for converter in field_converters:
-                value = converter(value, self.connection, self.query.context)
+            for converter in convs:
+                value = converter(value, expression, self.connection, self.query.context)
             row[pos] = value
         return tuple(row)
 

docs/howto/custom-model-fields.txt

@@ -483,7 +483,7 @@ instances::
     class HandField(models.Field):
         # ...
 
-        def from_db_value(self, value, connection, context):
+        def from_db_value(self, value, expression, connection, context):
             if value is None:
                 return value
             return parse_hand(value)

docs/ref/models/expressions.txt

@@ -416,7 +416,7 @@ calling the appropriate methods on the wrapped expression.
               clone.expression = self.expression.relabeled_clone(change_map)
               return clone
 
-    .. method:: convert_value(self, value, connection, context)
+    .. method:: convert_value(self, value, expression, connection, context)
 
         A hook allowing the expression to coerce ``value`` into a more
         appropriate type.

docs/ref/models/fields.txt

@@ -1679,7 +1679,7 @@ Field API reference
 
     When loading data, :meth:`from_db_value` is used:
 
-    .. method:: from_db_value(value, connection, context)
+    .. method:: from_db_value(value, expression, connection, context)
 
         .. versionadded:: 1.8
 

tests/custom_pk/fields.py

@@ -43,7 +43,7 @@ class MyAutoField(models.CharField):
             value = MyWrapper(value)
         return value
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         if not value:
             return
         return MyWrapper(value)

tests/from_db_value/models.py

@@ -18,7 +18,7 @@ class CashField(models.DecimalField):
         kwargs['decimal_places'] = 2
         super(CashField, self).__init__(**kwargs)
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         cash = Cash(value)
         cash.vendor = connection.vendor
         return cash

tests/serializers/models.py

@@ -112,7 +112,7 @@ class TeamField(models.CharField):
             return value
         return Team(value)
 
-    def from_db_value(self, value, connection, context):
+    def from_db_value(self, value, expression, connection, context):
         return Team(value)
 
     def value_to_string(self, obj):