How to: Filter targeting a sum()'s source query

[Estigy]

Package

Form builder

Package Version

v4

How can we help you?

I have a list of buildings and each building has rooms (1:n).
In the buildings table I have a column that is defined as sum("rooms", "size") as it sums all the rooms' size values.

Next step is to add a SelectFilter with room categories, and the sum() should only sum up the size of those rooms that match the selected category.
How would I do this?

A few things I tried but did not manage to give me the desired result:

1. A SelectFilter wants to match to a specific column. Is there a good way to have a filter but not have it want to find a column of the same name? Can I declare it as "virtual" so it does not inject anything into the query? I worked around this by calling query() with a shorthand function that returns the very same $query, but this feels hacky...
2. I tried to scope the relationship as seen in https://filamentphp.com/docs/4.x/tables/columns/overview#aggregating-relationships but when I wanted to add a second parameter (like $livewire or $component) to access the filters, I got an error "Too few arguments". It seems that parameter injection does not work there as expected.
3. I tried to use a regular function there to scope the relationship and inject the filter state using "use(...)" - but for this to work I would need to access and extract the current filter state somewhere before. What would be the best way to do that?

Thanks to everybody who would take time to offer any advice :-)

[D-Jordy]

what is your query now? I think I'd just write a conditional join clause, and change the joined rooms in the query() method of the filter

[Estigy]

Hi, D-Jordy!
I already tried that: The subquery that Filament produces for calculating the sum() is not related to the query users can provide via query().
That's the first thing I tried: Vary the joins based on the filter. But you can add joins inside your query() how ever you like - they will only be used to determin the lines that show up in the table. The subquery created for the sum() will always be the same and make a sum of all related models, not regarding the joins already provided.
That's why my thread has been specifically worded to inject a filter into a sum()'s subquery because currently it is always generated the same.