raise exception when if_not_exists is not capable.

raise exception when calling if_not_exists for table with counter
columns. refer to cqlengine#302 for details.

cqlengine/exceptions.py

@@ -5,3 +5,4 @@ class ValidationError(CQLEngineException): pass
 
 class UndefinedKeyspaceException(CQLEngineException): pass
 class LWTException(CQLEngineException): pass
+class IfNotExistsWithCounterColumn(CQLEngineException): pass

cqlengine/query.py

@@ -7,7 +7,7 @@ from cqlengine.columns import Counter, List, Set
 
 from .connection import execute, NOT_SET
 
-from cqlengine.exceptions import CQLEngineException, ValidationError, LWTException
+from cqlengine.exceptions import CQLEngineException, ValidationError, LWTException, IfNotExistsWithCounterColumn
 from cqlengine.functions import Token, BaseQueryFunction, QueryValue, UnicodeMixin
 
 #CQL 3 reference:
@@ -784,6 +784,8 @@ class ModelQuerySet(AbstractQuerySet):
         return clone
 
     def if_not_exists(self):
+        if self.model._has_counter:
+            raise IfNotExistsWithCounterColumn('if_not_exists cannot be used with tables containing columns')
         clone = copy.deepcopy(self)
         clone._if_not_exists = True
         return clone

cqlengine/tests/test_ifnotexists.py

@@ -3,7 +3,7 @@ from cqlengine.management import sync_table, drop_table, create_keyspace, delete
 from cqlengine.tests.base import BaseCassEngTestCase
 from cqlengine.tests.base import PROTOCOL_VERSION
 from cqlengine.models import Model
-from cqlengine.exceptions import LWTException
+from cqlengine.exceptions import LWTException, IfNotExistsWithCounterColumn
 from cqlengine import columns, BatchQuery
 from uuid import uuid4
 import mock
@@ -16,6 +16,12 @@ class TestIfNotExistsModel(Model):
     text    = columns.Text(required=False)
 
 
+class TestIfNotExistsWithCounterModel(Model):
+
+    id      = columns.UUID(primary_key=True, default=lambda:uuid4())
+    likes   = columns.Counter()
+
+
 class BaseIfNotExistsTest(BaseCassEngTestCase):
 
     @classmethod
@@ -31,10 +37,23 @@ class BaseIfNotExistsTest(BaseCassEngTestCase):
 
     @classmethod
     def tearDownClass(cls):
-        super(BaseCassEngTestCase, cls).tearDownClass()
+        super(BaseIfNotExistsTest, cls).tearDownClass()
         drop_table(TestIfNotExistsModel)
 
 
+class BaseIfNotExistsWithCounterTest(BaseCassEngTestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        super(BaseIfNotExistsWithCounterTest, cls).setUpClass()
+        sync_table(TestIfNotExistsWithCounterModel)
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BaseIfNotExistsWithCounterTest, cls).tearDownClass()
+        drop_table(TestIfNotExistsWithCounterModel)
+
+
 class IfNotExistsInsertTests(BaseIfNotExistsTest):
 
     @skipUnless(PROTOCOL_VERSION >= 2, "only runs against the cql3 protocol v2.0")
@@ -170,3 +189,14 @@ class IfNotExistsInstanceTest(BaseIfNotExistsTest):
         self.assertNotIn("IF NOT EXIST", query)
 
 
+class IfNotExistWithCounterTest(BaseIfNotExistsWithCounterTest):
+
+    def test_instance_raise_exception(self):
+        """ make sure exception is raised when calling
+        if_not_exists on table with counter column
+        """
+        id = uuid4()
+        self.assertRaises(
+            IfNotExistsWithCounterColumn,
+            TestIfNotExistsWithCounterModel.if_not_exists
+            )