Ticket #17587: fk_serialize.patch

django/core/serializers/python.py

@@ -50 +50 @@
             if self.use_natural_keys and hasattr(related, 'natural_key'):
                 related = related.natural_key()
             else:
-                if field.rel.field_name == related._meta.pk.name:
-                    # Related to remote object via primary key
-                    related = related._get_pk_val()
-                else:
-                    # Related to remote object via other field
-                    related = smart_unicode(getattr(related, field.rel.field_name), strings_only=True)
+                related_field = field.rel.get_related_field()
+                related = related_field.value_to_string(related)
         self._current[field.name] = related
 
     def handle_m2m_field(self, obj, field):

django/core/serializers/xml_serializer.py

@@ -96 +96 @@
                     self.xml.characters(smart_unicode(key_value))
                     self.xml.endElement("natural")
             else:
-                if field.rel.field_name == related._meta.pk.name:
-                    # Related to remote object via primary key
-                    related = related._get_pk_val()
-                else:
-                    # Related to remote object via other field
-                    related = getattr(related, field.rel.field_name)
+                related_field = field.rel.get_related_field()
+                related = related_field.value_to_string(related)
                 self.xml.characters(smart_unicode(related))
         else:
             self.xml.addQuickElement("None")

tests/modeltests/serializers/models.py

@@ -117 +117 @@
 
     def __unicode__(self):
         return u'%s (%d) playing for %s' % (self.name, self.rank, self.team.to_string())
+
+
+class ProductCode(object):
+    def __init__(self, code):
+        self.code = code
+
+    def __unicode__(self):
+        raise NotImplementedError("Not so simple")
+
+    def __str__(self):
+        raise NotImplementedError("Not so simple")
+
+    def to_string(self):
+        return u'%s' % self.code
+
+
+class ProductCodeField(models.CharField):
+    __metaclass__ = models.SubfieldBase
+
+    def __init__(self):
+        super(ProductCodeField, self).__init__(max_length=100, unique=True)
+
+    def get_prep_value(self, value):
+        if isinstance(value, ProductCode):
+            return unicode(value.code)
+        return value
+
+    def get_db_prep_save(self, value, connection):
+        return unicode(value.code)
+
+    def to_python(self, value):
+        if isinstance(value, ProductCode):
+            return value
+        return ProductCode(value)
+
+    def value_to_string(self, obj):
+        return self._get_val_from_obj(obj).to_string()
+
+
+class Product(models.Model):
+    code = ProductCodeField()
+
+    def __unicode__(self):
+        return u'product %s' % self.code.to_string()
+
+
+class Order(models.Model):
+    product = models.ForeignKey(Product, to_field='code')
+    amount = models.IntegerField()
+
+    def __unicode__(self):
+        return u'order for %d items of %s' % (self.amount, self.product)

tests/modeltests/serializers/tests.py

@@ -14 +14 @@
 from django.utils import simplejson, unittest
 
 from .models import (Category, Author, Article, AuthorProfile, Actor, Movie,
-    Score, Player, Team)
+    Score, Player, Team, Product, Order)
 
 
 class SerializerRegistrationTests(unittest.TestCase):
@@ -219 +219 @@
         self.assertEqual(deserial_objs[0].object.team.to_string(),
                          player.team.to_string())
 
+    def test_custom_field_foreign_key_serialization(self):
+        """Tests that custom fields as foreign keys serialize and deserialize intact"""
+        code_str = "AB1234"
+        product = Product()
+        product.code = code_str
+        product.save()
+
+        order = Order()
+        order.product = product
+        order.amount = 10
+        order.save()
+
+        serial_str = serializers.serialize(self.serializer_name,
+                                           Order.objects.all())
+        product = self._get_field_values(serial_str, "product")
+        self.assertTrue(product)
+        self.assertEqual(product[0], code_str)
+
+        deserial_objs = list(serializers.deserialize(self.serializer_name, serial_str))
+        self.assertEqual(deserial_objs[0].object.product.code.to_string(),
+                         order.product.code.to_string())
+
     def test_pre_1000ad_date(self):
         """Tests that year values before 1000AD are properly formatted"""
         # Regression for #12524 -- dates before 1000AD get prefixed