Added documentation. Changed .transaction() to .iff(), removed

TransactionException and replaced with LWTException

cqlengine/connection.py

@@ -5,7 +5,7 @@
 from collections import namedtuple
 from cassandra.cluster import Cluster, NoHostAvailable
 from cassandra.query import SimpleStatement, Statement
-from cqlengine.exceptions import TransactionException
+from cqlengine.exceptions import LWTException
 import six
 
 try:
@@ -112,12 +112,6 @@ def execute(query, params=None, consistency_level=None):
     params = params or {}
     result = session.execute(query, params)
 
-    if result and result[0].get('[applied]', True) is False:
-        result[0].pop('[applied]')
-        expected = ', '.join('{0}={1}'.format(t.field, t.value) for t in statement.transactions)
-        actual = ', '.join('{0}={1}'.format(f, v) for f, v in result[0].items())
-        message = 'Transaction statement failed: Expected: {0}  Actual: {1}'.format(expected, actual)
-        raise TransactionException(message)
     return result
 
 def get_session():

cqlengine/exceptions.py

@@ -2,7 +2,6 @@
 class CQLEngineException(Exception): pass
 class ModelException(CQLEngineException): pass
 class ValidationError(CQLEngineException): pass
-class TransactionException(CQLEngineException): pass
 
 class UndefinedKeyspaceException(CQLEngineException): pass
 class LWTException(CQLEngineException): pass

cqlengine/models.py

@@ -266,7 +266,7 @@ class BaseModel(object):
     objects = QuerySetDescriptor()
     ttl = TTLDescriptor()
     consistency = ConsistencyDescriptor()
-    transaction = TransactionDescriptor()
+    iff = TransactionDescriptor()
 
     # custom timestamps, see USING TIMESTAMP X
     timestamp = TimestampDescriptor()

cqlengine/query.py

@@ -5,7 +5,7 @@ from cqlengine import BaseContainerColumn, Map, columns
 from cqlengine.columns import Counter, List, Set
 
 from cqlengine.connection import execute
-from cqlengine.exceptions import CQLEngineException, ValidationError, TransactionException, LWTException
+from cqlengine.exceptions import CQLEngineException, ValidationError, LWTException
 from cqlengine.functions import Token, BaseQueryFunction, QueryValue, UnicodeMixin
 
 #CQL 3 reference:
@@ -849,14 +849,8 @@ class DMLQuery(object):
             return self._batch.add_query(q)
         else:
             tmp = execute(q, consistency_level=self._consistency)
-            if self._if_not_exists:
+            if self._if_not_exists or self._transaction:
                 check_applied(tmp)
-            if self._transaction and tmp[0].get('[applied]', True) is False:
-                tmp[0].pop('[applied]')
-                expected = ', '.join('{0}={1}'.format(t.field, t.value) for t in q.transactions)
-                actual = ', '.join('{0}={1}'.format(f, v) for f, v in tmp[0].items())
-                message = 'Transaction statement failed: Expected: {0}  Actual: {1}'.format(expected, actual)
-                raise TransactionException(message)
             return tmp
 
     def batch(self, batch_obj):
@@ -966,7 +960,7 @@ class DMLQuery(object):
         if self.instance._has_counter or self.instance._can_update():
             return self.update()
         else:
-            insert = InsertStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp, if_not_exists=self._if_not_exists, transactions=self._transaction)
+            insert = InsertStatement(self.column_family_name, ttl=self._ttl, timestamp=self._timestamp, if_not_exists=self._if_not_exists)
             for name, col in self.instance._columns.items():
                 val = getattr(self.instance, name, None)
                 if col._val_is_null(val):

cqlengine/tests/base.py

@@ -3,8 +3,11 @@ import os
 import sys
 import six
 from cqlengine.connection import get_session
+from cqlengine import connection
 
-CASSANDRA_VERSION = int(os.environ['CASSANDRA_VERSION'])
+CASSANDRA_VERSION = 20  #int(os.environ['CASSANDRA_VERSION'])
+
+connection.setup(['192.168.56.103'], 'cqlengine_test')
 
 class BaseCassEngTestCase(TestCase):
 

cqlengine/tests/test_transaction.py

@@ -2,7 +2,7 @@ __author__ = 'Tim Martin'
 from cqlengine.management import sync_table, drop_table
 from cqlengine.tests.base import BaseCassEngTestCase
 from cqlengine.models import Model
-from cqlengine.exceptions import TransactionException
+from cqlengine.exceptions import LWTException
 from uuid import uuid4
 from cqlengine import columns
 import mock
@@ -41,7 +41,7 @@ class TestTransaction(BaseCassEngTestCase):
         t = TestTransactionModel.create(text='blah blah')
         t.text = 'new blah'
         t = t.iff(text='something wrong')
-        self.assertRaises(TransactionException, t.save)
+        self.assertRaises(LWTException, t.save)
 
     def test_blind_update(self):
         t = TestTransactionModel.create(text='blah blah')
@@ -59,4 +59,4 @@ class TestTransaction(BaseCassEngTestCase):
         t.text = 'something else'
         uid = t.id
         qs = TestTransactionModel.objects(id=uid).iff(text='Not dis!')
-        self.assertRaises(TransactionException, qs.update, text='this will never work')
+        self.assertRaises(LWTException, qs.update, text='this will never work')

docs/topics/models.rst

@@ -207,6 +207,14 @@ Model Methods
 
         This method is supported on Cassandra 2.0 or later.
 
+    .. method:: iff(**values)
+
+        Checks to ensure that the values specified are correct on the Cassandra cluster.
+        Simply specify the column(s) and the expected value(s).  As with if_not_exists,
+        this incurs a performance cost.
+
+        If the insertion isn't applied, a LWTException is raised
+
     .. method:: update(**values)
 
         Performs an update on the model instance. You can pass in values to set on the model