def getSubgraphFieldCount(self, parent_name, graph_name):
graph = self._getSubGraph(parent_name, graph_name, True)<EOL>return graph.getFieldCount()<EOL>
Returns number of fields for subgraph with name graph_name and parent 
        graph with name parent_name.

        @param parent_name: Root Graph Name
        @param graph_name:  Subgraph Name
        @return:            Number of fields for subgraph.