It is common for you to want to have widgets on the top of your grid that influence the grids filtering. External filtering allows you to mix your own 'outside of the grid' filtering with the grids filtering.
The example below shows external filters in action. There are two methods on gridOptions you
need to implement:
isExternalFilterPresentis called exactly once every time the grid senses a filter change. It should return true if external filtering is active, otherwise false. If you return true, then doesExternalFilterPass() will be called while filtering, otherwise doesExternalFilterPass() will not be called.
doesExternalFilterPassis called once for each row node in the grid. If you return false, the node will be excluded from the final set.
The example below shows the external filters in action.