Allow to load a query-based SQLite layer without geometry

src/providers/spatialite/qgsspatialiteprovider.cpp

@@ -4145,7 +4145,7 @@ bool QgsSpatiaLiteProvider::checkLayerType()
 
   QString sql;
 
-  if ( mGeometryColumn.isEmpty() )
+  if ( mGeometryColumn.isEmpty() && !(mQuery.startsWith( "(" ) && mQuery.endsWith( ")" )) )
   {
     // checking if is a non-spatial table
     sql = QString( "SELECT type FROM sqlite_master "

tests/src/python/test_qgsspatialiteprovider.py

@@ -70,6 +70,18 @@ def setUpClass(cls):
         sql +=    "VALUES (1, 'toto', GeomFromText('POLYGON((0 0,1 0,1 1,0 1,0 0))', 4326))"
         cur.execute(sql)
 
+        # simple table with primary key
+        sql = "CREATE TABLE test_q (id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL)"
+        cur.execute(sql)
+        sql = "SELECT AddGeometryColumn('test_q', 'geometry', 4326, 'POLYGON', 'XY')"
+        cur.execute(sql)
+        sql = "INSERT INTO test_q (id, name, geometry) "
+        sql +=    "VALUES (1, 'toto', GeomFromText('POLYGON((0 0,1 0,1 1,0 1,0 0))', 4326))"
+        cur.execute(sql)
+        sql = "INSERT INTO test_q (id, name, geometry) "
+        sql +=    "VALUES (2, 'toto', GeomFromText('POLYGON((0 0,1 0,1 1,0 1,0 0))', 4326))"
+        cur.execute(sql)
+
         cur.execute( "COMMIT" )
         con.close()
 
@@ -122,5 +134,36 @@ def xtest_SplitFeatureWithFailedCommit(self):
                 for c1, c2 in zip(p1, p2):
                     c1 == c2 or die("polygon has been altered by failed edition")
 
+    def test_queries(self):
+        """Test loading of query-based layers"""
+
+        # a query with a geometry, but no unique id
+        # this allows to load a query without unique id
+        # however, functions relying on such a unique id would fail
+        l = QgsVectorLayer("dbname=%s table='(select * from test_q)' (geometry)" % self.dbname, "test_pg_query1", "spatialite")
+        assert(l.isValid())
+        # the id() is not consistent
+        sum_id1 = sum(f.id() for f in l.getFeatures())
+        # the attribute 'id' works
+        sum_id2 = sum(f.attributes()[0] for f in l.getFeatures())
+        assert(sum_id1 == 0)
+        assert(sum_id2 == 3)
+
+        # and now with an id declared
+        l = QgsVectorLayer("dbname=%s table='(select * from test_q)' (geometry) key='id'" % self.dbname, "test_pg_query1", "spatialite")
+        assert(l.isValid())
+        sum_id1 = sum(f.id() for f in l.getFeatures())
+        sum_id2 = sum(f.attributes()[0] for f in l.getFeatures())
+        assert(sum_id1 == 3)
+        assert(sum_id2 == 3)
+
+        # a query, but no geometry
+        l = QgsVectorLayer("dbname=%s table='(select id,name from test_q)' key='id'" % self.dbname, "test_pg_query1", "spatialite")
+        assert(l.isValid())
+        sum_id1 = sum(f.id() for f in l.getFeatures())
+        sum_id2 = sum(f.attributes()[0] for f in l.getFeatures())
+        assert(sum_id1 == 3)
+        assert(sum_id2 == 3)
+
 if __name__ == '__main__':
     unittest.main()