The filter of a Grid/AutoGrid should be accessible from outside the Grid/AutoGrid

[alxflam]

Describe your motivation

It's a common use case for many applications to allow users to export/download data of grids (e.g. as CSV, XLSX). This can be done in Hilla by making use of a plain Spring RestController which provides the export/download endpoint and dynamically creates the file. Now the problem is: The backend endpoint needs to know exactly which data should be included in the resulting file, and thus the current filter state of the grid needs to be passed to the download endpoint.

Describe the solution you'd like

Maybe this could be done similar to #1769 which created an accessible refresh trigger.

Create a react ref for the grid: const ref = useRef<AutoGridRef>(null); Then use this ref to collect the filter in the client download event handler to get the filter and pass it to the actual download/export endpoint: const filter = ref.current?.filter();

The filter only needs to be read. Changing the filter programmatically is not required for the mentioned use case.

Describe alternatives you've considered

• Producing the file export on the Hilla client-app is usually not feasible, e.g. due to pagination anyways not all the data is loaded yet in the frontend. Additionally, it's also most likely simply not desirable, the backend will have much better ways to achieve different export formats like CSV, XLSX, PDF, ...

Additional context

Origin: https://vaadin.com/forum/t/hilla-endpoint-with-custom-headers-e-g-for-file-download/165993/2

[sagarbendale]

I would like to mention, that it is very common to retain the filter and apply it before the list is initialized. eg. user navigates away from the list page and then comes back. Along with read capability writing to the filter is also much needed.