From eab5df12b664b154b2e280330aa43d8c0621b94a Mon Sep 17 00:00:00 2001
From: Tim Graham <timograham@gmail.com>
Date: Fri, 22 Apr 2016 13:43:05 -0400
Subject: [PATCH] Refs #22936 -- Moved more of Field.get_db_prep_lookup() to
 lookups.

---
 django/db/models/fields/__init__.py |  9 +-----
 django/db/models/lookups.py         | 46 +++++++++++++++++++++++------
 2 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index ec6cf3cf29..5951681e81 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -783,14 +783,7 @@ class Field(RegisterLookupMixin):
             value = self.get_prep_lookup(lookup_type, value)
             prepared = True
 
-        if lookup_type in ('exact', 'gt', 'gte', 'lt', 'lte'):
-            return [self.get_db_prep_value(value, connection=connection,
-                                           prepared=prepared)]
-        elif lookup_type in ('range', 'in'):
-            return [self.get_db_prep_value(v, connection=connection,
-                                           prepared=prepared) for v in value]
-        else:
-            return [value]
+        return [value]
 
     def has_default(self):
         """
diff --git a/django/db/models/lookups.py b/django/db/models/lookups.py
index ad55a0138d..62acfcb887 100644
--- a/django/db/models/lookups.py
+++ b/django/db/models/lookups.py
@@ -51,8 +51,7 @@ class Lookup(object):
                 sqls.append(sql)
                 sqls_params.extend(sql_params)
         else:
-            params = self.lhs.output_field.get_db_prep_lookup(
-                self.lookup_name, rhs, connection, prepared=True)
+            _, params = self.get_db_prep_lookup(rhs, connection)
             sqls, sqls_params = ['%s'] * len(params), params
         return sqls, sqls_params
 
@@ -164,7 +163,36 @@ class BuiltinLookup(Lookup):
         return connection.operators[self.lookup_name] % rhs
 
 
-class Exact(BuiltinLookup):
+class FieldGetDbPrepValueMixin(object):
+    """
+    Some lookups require Field.get_db_prep_value() to be called on their
+    inputs.
+    """
+    get_db_prep_lookup_value_is_iterable = False
+
+    def get_db_prep_lookup(self, value, connection):
+        # For relational fields, use the output_field of the 'field' attribute.
+        field = getattr(self.lhs.output_field, 'field', None)
+        get_db_prep_value = getattr(field, 'get_db_prep_value', None)
+        if not get_db_prep_value:
+            get_db_prep_value = self.lhs.output_field.get_db_prep_value
+        return (
+            '%s',
+            [get_db_prep_value(v, connection, prepared=True) for v in value]
+            if self.get_db_prep_lookup_value_is_iterable else
+            [get_db_prep_value(value, connection, prepared=True)]
+        )
+
+
+class FieldGetDbPrepValueIterableMixin(FieldGetDbPrepValueMixin):
+    """
+    Some lookups require Field.get_db_prep_value() to be called on each value
+    in an iterable.
+    """
+    get_db_prep_lookup_value_is_iterable = True
+
+
+class Exact(FieldGetDbPrepValueMixin, BuiltinLookup):
     lookup_name = 'exact'
 Field.register_lookup(Exact)
 
@@ -182,22 +210,22 @@ class IExact(BuiltinLookup):
 Field.register_lookup(IExact)
 
 
-class GreaterThan(BuiltinLookup):
+class GreaterThan(FieldGetDbPrepValueMixin, BuiltinLookup):
     lookup_name = 'gt'
 Field.register_lookup(GreaterThan)
 
 
-class GreaterThanOrEqual(BuiltinLookup):
+class GreaterThanOrEqual(FieldGetDbPrepValueMixin, BuiltinLookup):
     lookup_name = 'gte'
 Field.register_lookup(GreaterThanOrEqual)
 
 
-class LessThan(BuiltinLookup):
+class LessThan(FieldGetDbPrepValueMixin, BuiltinLookup):
     lookup_name = 'lt'
 Field.register_lookup(LessThan)
 
 
-class LessThanOrEqual(BuiltinLookup):
+class LessThanOrEqual(FieldGetDbPrepValueMixin, BuiltinLookup):
     lookup_name = 'lte'
 Field.register_lookup(LessThanOrEqual)
 
@@ -223,7 +251,7 @@ class IntegerLessThan(IntegerFieldFloatRounding, LessThan):
 IntegerField.register_lookup(IntegerLessThan)
 
 
-class In(BuiltinLookup):
+class In(FieldGetDbPrepValueIterableMixin, BuiltinLookup):
     lookup_name = 'in'
 
     def process_rhs(self, compiler, connection):
@@ -365,7 +393,7 @@ class IEndsWith(PatternLookup):
 Field.register_lookup(IEndsWith)
 
 
-class Range(BuiltinLookup):
+class Range(FieldGetDbPrepValueIterableMixin, BuiltinLookup):
     lookup_name = 'range'
 
     def get_rhs_op(self, connection, rhs):