fix handling of null values for feature id in sqlite/postgis input - closes #1817

plugins/input/postgis/postgis_featureset.cpp

@@ -75,10 +75,17 @@ feature_ptr postgis_featureset::next()
 
         if (key_field_)
         {
+            std::string name = rs_->getFieldName(pos);
+
+            // null feature id is not acceptable
+            if (rs_->isNull(pos))
+            {
+                MAPNIK_LOG_WARN(postgis) << "postgis_featureset: null value encountered for key_field: " << name;
+                continue;
+            }
             // create feature with user driven id from attribute
             int oid = rs_->getTypeOID(pos);
             const char* buf = rs_->getValue(pos);
-            std::string name = rs_->getFieldName(pos);
 
             // validation happens of this type at initialization
             mapnik::value_integer val;

plugins/input/sqlite/sqlite_featureset.cpp

@@ -71,6 +71,13 @@ feature_ptr sqlite_featureset::next()
             return feature_ptr();
         }
 
+        // null feature id is not acceptable
+        if (rs_->column_type(1) == SQLITE_NULL)
+        {
+            MAPNIK_LOG_ERROR(postgis) << "sqlite_featureset: null value encountered for key_field";
+            continue;
+        }
+
         feature_ptr feature = feature_factory::create(ctx_,rs_->column_integer64(1));
         if (!geometry_utils::from_wkb(feature->paths(), data, size, format_))
             continue;

tests/python_tests/postgis_test.py

@@ -626,6 +626,28 @@ if 'postgis' in mapnik.DatasourceCache.plugin_names() \
         except Exception, e:
             eq_(e.message != 'unidentifiable C++ exception', True)
 
+    def test_null_id_field():
+        opts = {'type':'postgis',
+                'dbname':MAPNIK_TEST_DBNAME,
+                'geometry_field':'geom',
+                'table':"(select null::bigint as osm_id, GeomFromEWKT('SRID=4326;POINT(0 0)') as geom) as tmp"}
+        ds = mapnik.Datasource(**opts)
+        fs = ds.featureset()
+        feat = fs.next()
+        eq_(feat.id(),1L)
+        eq_(feat['osm_id'],None)
+
+    @raises(StopIteration)
+    def test_null_key_field():
+        opts = {'type':'postgis',
+                "key_field": 'osm_id',
+                'dbname':MAPNIK_TEST_DBNAME,
+                'geometry_field':'geom',
+                'table':"(select null::bigint as osm_id, GeomFromEWKT('SRID=4326;POINT(0 0)') as geom) as tmp"}
+        ds = mapnik.Datasource(**opts)
+        fs = ds.featureset()
+        feat = fs.next() ## should throw since key_field is null: StopIteration: No more features.
+
     atexit.register(postgis_takedown)
 
 if __name__ == "__main__":

tests/python_tests/sqlite_test.py

@@ -379,6 +379,27 @@ if 'sqlite' in mapnik.DatasourceCache.plugin_names():
         eq_(feat['OGC_FID'],2)
         eq_(feat['bigint'],922337203685477580)
 
+
+    @raises(StopIteration)
+    def test_null_id_field():
+        # form up an in-memory test db
+        wkb = '010100000000000000000000000000000000000000'
+        # note: the osm_id should be declared INTEGER PRIMARY KEY
+        # but in this case we intentionally do not make this a valid pkey
+        # otherwise sqlite would turn the null into a valid, serial id
+        ds = mapnik.SQLite(file=':memory:',
+            table='test1',
+            initdb='''
+                create table test1 (osm_id INTEGER,geometry BLOB);
+                insert into test1 values (null,x'%s');
+                ''' % wkb,
+            extent='-180,-60,180,60',
+            use_spatial_index=False,
+            key_field='osm_id'
+        )
+        fs = ds.featureset()
+        feat = fs.next() ## should throw since key_field is null: StopIteration: No more features.
+
 if __name__ == "__main__":
     setup()
     [eval(run)() for run in dir() if 'test_' in run]