jqGrid local filtering

Here I have a search form and a grid. The grid has configured a URL and datatype 'json'.

When search form submit, it will trigger grid reload, with parameters collected in the search form get submitted.

Now I want to add local filtering ability using filterToolbar. i.e. let the user filter the result on-screen. So the sear开发者_开发百科ch form remains a server-search. The toolbar is for local-search.

I tried using beforeSearch and afterSearch

var g = $("#grid").filterToolbar({
    beforeSearch: function(){ g.setGridParam({datatype:'local'}); },
    afterSearch: function(){ g.setGridParam({datatype:'json'}); }
})

but it turn out that once datatype:'local' is applied, any search in filterToolbar will remove all record on screen.

As I still want the server-search, I don't use loadonce .

Any other way to do that?