Fix provider ordering by test to correctly also test compiled order by

...and as a result, disable compiled order by support for postgres
due to bugs exposed by the test

Author: nyalldawson

src/providers/postgres/qgspostgresfeatureiterator.cpp

@@ -116,6 +116,14 @@ QgsPostgresFeatureIterator::QgsPostgresFeatureIterator( QgsPostgresFeatureSource
 
   mOrderByCompiled = true;
 
+  // THIS CODE IS BROKEN - since every retrieved column is cast as text during declareCursor, this method of sorting will always be
+  // performed using a text sort.
+  // TODO - fix ordering by so that instead of
+  //     SELECT my_int_col::text FROM some_table ORDER BY my_int_col
+  // we instead use
+  //     SELECT my_int_col::text FROM some_table ORDER BY some_table.my_int_col
+  // but that's non-trivial
+#if 0
   if ( QSettings().value( "/qgis/compileExpressions", true ).toBool() )
   {
     Q_FOREACH ( const QgsFeatureRequest::OrderByClause& clause, request.orderBy() )
@@ -142,6 +150,7 @@ QgsPostgresFeatureIterator::QgsPostgresFeatureIterator( QgsPostgresFeatureSource
     }
   }
   else
+#endif
   {
     mOrderByCompiled = false;
   }

tests/src/python/providertestbase.py

@@ -161,7 +161,21 @@ def getSubsetString(self):
         """Individual providers may need to override this depending on their subset string formats"""
         return '"cnt" > 100 and "cnt" < 410'
 
-    def testOrderBy(self):
+    def testOrderByUncompiled(self):
+        try:
+            self.disableCompiler()
+        except AttributeError:
+            pass
+        self.runOrderByTests()
+
+    def testOrderByCompiled(self):
+        try:
+            self.enableCompiler()
+            self.runOrderByTests()
+        except AttributeError:
+            print 'Provider does not support compiling'
+
+    def runOrderByTests(self):
         request = QgsFeatureRequest().addOrderBy('cnt')
         values = [f['cnt'] for f in self.provider.getFeatures(request)]
         self.assertEquals(values, [-200, 100, 200, 300, 400])
@@ -201,6 +215,11 @@ def testOrderBy(self):
         values = [f['pk'] for f in self.provider.getFeatures(request)]
         self.assertEquals(values, [5, 4, 3, 2, 1])
 
+        # Order reversing expression
+        request = QgsFeatureRequest().addOrderBy('pk*-1', False)
+        values = [f['pk'] for f in self.provider.getFeatures(request)]
+        self.assertEquals(values, [1, 2, 3, 4, 5])
+
         # Type dependent expression
         request = QgsFeatureRequest().addOrderBy('num_char*2', False)
         values = [f['pk'] for f in self.provider.getFeatures(request)]