Fix for #674.

peewee.py

@@ -1543,7 +1543,8 @@ def _parse(self, node, alias_map, conv):
             sql = '(%s)' % sql
         elif isinstance(node, Model):
             sql = self.interpolation
-            if conv and isinstance(conv, ForeignKeyField):
+            if conv and isinstance(conv, ForeignKeyField) and \
+                    not isinstance(conv.to_field, ForeignKeyField):
                 params = [
                     conv.to_field.db_value(getattr(node, conv.to_field.name))]
             else:

playhouse/tests/models.py

@@ -190,6 +190,10 @@ class JobExecutionRecord(TestModel):
     status = CharField()
 
 
+class JERRelated(TestModel):
+    jer = ForeignKeyField(JobExecutionRecord)
+
+
 class TestModelA(TestModel):
     field = CharField(primary_key=True)
     data = CharField()
@@ -363,6 +367,7 @@ class EmptyModel(TestModel):
     BlobModel,
     Job,
     JobExecutionRecord,
+    JERRelated,
     TestModelA,
     TestModelB,
     TestModelC,

playhouse/tests/test_fields.py

@@ -522,7 +522,7 @@ def test_non_int_fk(self):
 
 
 class TestPrimaryKeyIsForeignKey(ModelTestCase):
-    requires = [Job, JobExecutionRecord]
+    requires = [Job, JobExecutionRecord, JERRelated]
 
     def test_primary_foreign_key(self):
         # we have one job, unexecuted, and therefore no executed jobs
@@ -539,6 +539,23 @@ def test_primary_foreign_key(self):
         self.assertRaises(Exception, JobExecutionRecord.create, job=job, status='success')
         test_db.rollback()
 
+    def test_pk_fk_relations(self):
+        j1 = Job.create(name='j1')
+        j2 = Job.create(name='j2')
+        jer1 = JobExecutionRecord.create(job=j1, status='1')
+        jer2 = JobExecutionRecord.create(job=j2, status='2')
+        jerr1 = JERRelated.create(jer=jer1)
+        jerr2 = JERRelated.create(jer=jer2)
+
+        jerr_j1 = [x for x in jer1.jerrelated_set]
+        self.assertEqual(jerr_j1, [jerr1])
+
+        jerr_j2 = [x for x in jer2.jerrelated_set]
+        self.assertEqual(jerr_j2, [jerr2])
+
+        jerr1_db = JERRelated.get(JERRelated.jer == j1)
+        self.assertEqual(jerr1_db, jerr1)
+
 
 class TestFieldDatabaseColumn(ModelTestCase):
     requires = [DBUser, DBBlog]