Fix unreported issue with fields not retrieved for certain PG tables

qgis · Sep 24, 2020 · 83a4c7c · 83a4c7c
1 parent 69d66a1
commit 83a4c7c
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Showing 3 changed files with 70 additions and 2 deletions.
diff --git a/src/providers/postgres/qgspostgresproviderconnection.cpp b/src/providers/postgres/qgspostgresproviderconnection.cpp
@@ -656,3 +656,48 @@ QList<QgsVectorDataProvider::NativeType> QgsPostgresProviderConnection::nativeTy
   }
   return types;
 }
+
+
+QgsFields QgsPostgresProviderConnection::fields( const QString &schema, const QString &tableName ) const
+{
+  // Try the base implementation first and fall back to a more complex approch for the
+  // few PG-specific corner cases that do not work with the base implementation.
+  try
+  {
+    return QgsAbstractDatabaseProviderConnection::fields( schema, tableName );
+  }
+  catch ( QgsProviderConnectionException &ex )
+  {
+    // This table might expose multiple geometry columns (different geom type or SRID)
+    // but we are only interested in fields here, so let's pick the first one.
+    TableProperty tableInfo { table( schema, tableName ) };
+    if ( tableInfo.geometryColumnTypes().count( ) > 1 )
+    {
+      try
+      {
+        QgsDataSourceUri tUri { tableUri( schema, tableName ) };
+        TableProperty::GeometryColumnType geomCol { tableInfo.geometryColumnTypes().first() };
+        tUri.setGeometryColumn( tableInfo.geometryColumn() );
+        tUri.setWkbType( geomCol.wkbType );
+        tUri.setSrid( QString::number( geomCol.crs.postgisSrid() ) );
+        if ( tableInfo.primaryKeyColumns().count() > 0 )
+        {
+          tUri.setKeyColumn( tableInfo.primaryKeyColumns().first() );
+        }
+        tUri.setParam( QStringLiteral( "checkPrimaryKeyUnicity" ), QLatin1String( "0" ) );
+        QgsVectorLayer::LayerOptions options { true, true };
+        options.skipCrsValidation = true;
+        QgsVectorLayer vl { tUri.uri(), QStringLiteral( "temp_layer" ), mProviderKey, options };
+        if ( vl.isValid() )
+        {
+          return vl.fields();
+        }
+      }
+      catch ( QgsProviderConnectionException & )
+      {
+        // fall-through
+      }
+    }
+    throw ex;
+  }
+}
diff --git a/src/providers/postgres/qgspostgresproviderconnection.h b/src/providers/postgres/qgspostgresproviderconnection.h
@@ -38,6 +38,7 @@ class QgsPostgresProviderConnection : public QgsAbstractDatabaseProviderConnecti
                             const QMap<QString, QVariant> *options ) const override;
 
     QString tableUri( const QString &schema, const QString &name ) const override;
+    QgsFields fields( const QString &schema, const QString &table ) const override;
     void dropVectorTable( const QString &schema, const QString &name ) const override;
     void dropRasterTable( const QString &schema, const QString &name ) const override;
     void renameVectorTable( const QString &schema, const QString &name, const QString &newName ) const override;
@@ -65,9 +66,7 @@ class QgsPostgresProviderConnection : public QgsAbstractDatabaseProviderConnecti
     void dropTablePrivate( const QString &schema, const QString &name ) const;
     void renameTablePrivate( const QString &schema, const QString &name, const QString &newName ) const;
 
-
 };
 
 
-
 #endif // QGSPOSTGRESPROVIDERCONNECTION_H
diff --git a/tests/src/python/test_qgsproviderconnection_postgres.py b/tests/src/python/test_qgsproviderconnection_postgres.py
@@ -329,6 +329,30 @@ def test_fields(self):
         fields = conn.fields('qgis_test', 'someData')
         self.assertEqual(fields.names(), ['pk', 'cnt', 'name', 'name2', 'num_char', 'dt', 'date', 'time', 'geom'])
 
+    def test_fields_no_pk(self):
+        """Test issue: no fields are exposed for raster_columns"""
+
+        md = QgsProviderRegistry.instance().providerMetadata('postgres')
+        conn = md.createConnection(self.uri, {})
+        fields = conn.fields("public", "raster_columns")
+        self.assertEqual(fields.names(), [
+            'r_table_catalog',
+            'r_table_schema',
+            'r_table_name',
+            'r_raster_column',
+            'srid',
+            'scale_x',
+            'scale_y',
+            'blocksize_x',
+            'blocksize_y',
+            'same_alignment',
+            'regular_blocking',
+            'num_bands',
+            'pixel_types',
+            'nodata_values',
+            'out_db',
+            'spatial_index'])
+
 
 if __name__ == '__main__':
     unittest.main()