update datasource for grid with conbobox value

I want to make a grid panel that waits to have a value selected in a combo box before showing the contents.

I'm using an object datasource that is tied to an Ext store. I'm just looking for the best way to update the datasource and display the data after each selection in the combo box.

I can easiely set up the grid so that it displays the data on load by setting the default value of the select parameter of the data source but I'm a little at a lose on how to accomplish this client side using Coolite and Ext.

I'm to the point where I have a simple javascript message box displaying the value of the combo box after a new selection is made but I'm struggling with how to get the grid panel to update the data source based on this value.

Any suggestions would be appreciated.