PK fields should only be read-only if they are an AutoField. Fixes #563

2 files changed, 20 insertions, 2 deletions

diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 0bacacda..27458f96 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -415,7 +415,7 @@ class ModelSerializer(Serializer):
         """
         Returns a default instance of the pk field.
         """
-        return Field()
+        return self.get_field(model_field)
 
     def get_nested_field(self, model_field):
         """
@@ -452,7 +452,7 @@ class ModelSerializer(Serializer):
         if model_field.null or model_field.blank:
             kwargs['required'] = False
 
-        if not model_field.editable:
+        if isinstance(model_field, models.AutoField) or not model_field.editable:
             kwargs['read_only'] = True
 
         if model_field.has_default():
@@ -468,6 +468,7 @@ class ModelSerializer(Serializer):
             return ChoiceField(**kwargs)
 
         field_mapping = {
+            models.AutoField: IntegerField,
             models.FloatField: FloatField,
             models.IntegerField: IntegerField,
             models.PositiveIntegerField: IntegerField,
diff --git a/rest_framework/tests/fields.py b/rest_framework/tests/fields.py
index b1a8161a..a6a05941 100644
--- a/rest_framework/tests/fields.py
+++ b/rest_framework/tests/fields.py
@@ -12,11 +12,20 @@ class TimestampedModel(models.Model):
     updated = models.DateTimeField(auto_now=True)
 
 
+class CharPrimaryKeyModel(models.Model):
+    id = models.CharField(max_length=20, primary_key=True)
+
+
 class TimestampedModelSerializer(serializers.ModelSerializer):
     class Meta:
         model = TimestampedModel
 
 
+class CharPrimaryKeyModelSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = CharPrimaryKeyModel
+
+
 class ReadOnlyFieldTests(TestCase):
     def test_auto_now_fields_read_only(self):
         """
@@ -24,3 +33,11 @@ class ReadOnlyFieldTests(TestCase):
         """
         serializer = TimestampedModelSerializer()
         self.assertEquals(serializer.fields['added'].read_only, True)
+
+    def test_auto_pk_fields_read_only(self):
+        serializer = TimestampedModelSerializer()
+        self.assertEquals(serializer.fields['id'].read_only, True)
+
+    def test_non_auto_pk_fields_not_read_only(self):
+        serializer = CharPrimaryKeyModelSerializer()
+        self.assertEquals(serializer.fields['id'].read_only, False)