From 33d330cc405e79256eb5cf3a67787c92fba0cb52 Mon Sep 17 00:00:00 2001
From: stephenrauch <stephenrauch@users.noreply.github.com>
Date: Tue, 26 May 2015 18:57:45 -0700
Subject: [PATCH] fix belong() with empty set for MongoDB and GAE

fix ~ with == and != for MongoDB and GAE
---
 pydal/adapters/google_adapters.py |  9 ++++++++-
 pydal/adapters/mongo.py           | 17 +++++++++++++----
 tests/nosql.py                    |  3 +++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/pydal/adapters/google_adapters.py b/pydal/adapters/google_adapters.py
index 71aef5999..6b4c793af 100644
--- a/pydal/adapters/google_adapters.py
+++ b/pydal/adapters/google_adapters.py
@@ -311,6 +311,11 @@ def BELONGS(self,first,second=None):
             raise SyntaxError("Not supported")
         if not isinstance(second, list):
             second = list(second)
+        if len(second) == 0:
+            # return a filter which will return a null set
+            f = self.EQ(first,0)
+            f.filter_all = True
+            return f
         return self.gaef(first,'in',second)
 
     def CONTAINS(self,first,second,case_sensitive=False):
@@ -327,7 +332,7 @@ def NOT(self, first):
         elif op == self.EQ:
             r = self.gaef(f, '!=', s)
         elif op == self.NE:
-            r = self.gaef(f, '==', s)
+            r = self.gaef(f, '=', s)
         elif op == self.LT:
             r = self.gaef(f, '>=', s)
         elif op == self.LE:
@@ -409,6 +414,8 @@ def select_raw(self,query,fields=None,attributes=None,count_only=False):
 
         if filters == None:
             items = tableobj.query(default_options=qo)
+        elif hasattr(filters,'filter_all') and filters.filter_all:
+            items = []
         elif (hasattr(filters,'_FilterNode__name') and
             filters._FilterNode__name=='__key__' and
             filters._FilterNode__opsymbol=='='):
diff --git a/pydal/adapters/mongo.py b/pydal/adapters/mongo.py
index 89fe03f9a..104aac7f4 100644
--- a/pydal/adapters/mongo.py
+++ b/pydal/adapters/mongo.py
@@ -443,6 +443,7 @@ def NOT(self, first):
         op = self.expand(first)
         op_k = list(op)[0]
         op_body = op[op_k]
+        r = None
         if type(op_body) is list:
             # apply De Morgan law for and/or
             # not(A and B) -> not(A) or not(B)
@@ -450,7 +451,14 @@ def NOT(self, first):
             not_op = '$and' if op_k == '$or' else '$or'
             r = {not_op: [self.NOT(first.first), self.NOT(first.second)]}
         else:
-            r = {op_k: {'$not': op_body}}
+            try:
+                sub_ops = list(op_body.keys())
+                if len(sub_ops) == 1 and sub_ops[0] == '$ne':
+                    r = {op_k: op_body['$ne']}
+            except:
+                r = {op_k: {'$ne': op_body}}
+            if r == None:
+                r = {op_k: {'$not': op_body}}
         return r
 
     def AND(self,first,second):
@@ -463,9 +471,10 @@ def OR(self,first,second):
 
     def BELONGS(self, first, second):
         if isinstance(second, str):
-            return {self.expand(first) : {"$in" : [ second[:-1]]} }
-        elif second==[] or second==() or second==set():
-            return {1:0}
+            # this is broken, the only way second is a string is if it has
+            # been converted to SQL.  This no worky.  This might be made to
+            # work if _select did not return SQL.
+            raise RuntimeError("nested queries not supported")
         items = [self.expand(item, first.type) for item in second]
         return {self.expand(first) : {"$in" : items} }
 
diff --git a/tests/nosql.py b/tests/nosql.py
index 766c63b9f..86b14fea3 100644
--- a/tests/nosql.py
+++ b/tests/nosql.py
@@ -327,6 +327,8 @@ def testRun(self):
         self.assertEqual(db((db.tt.aa > '1') & (db.tt.aa < '3')).count(), 1)
         self.assertEqual(db((db.tt.aa > '1') | (db.tt.aa < '3')).count(), 3)
         # Test not operator
+        self.assertEqual(db(~(db.tt.aa != '1')).count(), 1)
+        self.assertEqual(db(~(db.tt.aa == '1')).count(), 2)
         self.assertEqual(db((db.tt.aa > '1') & ~(db.tt.aa > '2')).count(), 1)
         self.assertEqual(db(~(db.tt.aa > '1') & (db.tt.aa > '2')).count(), 0)
         self.assertEqual(db(~((db.tt.aa < '1') | (db.tt.aa > '2'))).count(), 2)
@@ -410,6 +412,7 @@ def testRun(self):
         self.assertEqual(db(db.tt.aa.belongs(['1', '3'])).count(), 2)
         self.assertEqual(db(db.tt.aa.belongs(['1', '3'])).count(), 2)
         self.assertEqual(db(db.tt.id.belongs([self.i_id])).count(), 1)
+        self.assertEqual(db(db.tt.id.belongs([])).count(), 0)
 
     @unittest.skipIf(IS_GAE or IS_MONGODB, "Datastore/Mongodb belongs() does not accept nested queries")
     def testNested(self):