My solution for filtering by the belongsTo relation

[rajabilal555]

Since there is no simple way of using the built in HttpFilter to filter relations, I have come up with a way to filter at least the basic belongsTo relations with out defining custom Filter classes...

Here is the basic code for it.
the TD::make's name parameter should be same as the column in the db (in this case sub_subject_id).
If you have not too many Records in the "sub_subject" table like this example, then you can use the following:

TD::make('sub_subject_id', 'Sub Subject')->render(function ($value) {
    return $value->sub_subject->name;
})->filter(TD::FILTER_SELECT, SubSubject::all()->pluck('name','id'))->sort(),

Preview:

If you want Lazy Loaded dropdown and have a lot of records in the table then you can use the following:

TD::make('sub_subject_id', 'Sub Subject')->render(function (ScreenModel $value) {
    return $value->sub_subject->name;
})->filter(Relation::make()->fromModel(SubSubject::class,'name'))->sort(),

The only problem with the Relation Field approach is that it will show the id instead of the name when filtering...
Preview:

I have not yet come up with a work around for the Relation field Filter tag, maybe some one can help with that... ?

Caveats: If you have a lot of Records you will probably have to go the Custom Filter Route as the current solution doesn't look as good.

[iFrez]

Hello, as a workaround you can override TD.php and modify buildFilterString() to looks like

if ($this->column == "column_name_id") {
$Model = Model::whereId($filter)->first();
return $Model === null ? $filter : $Model->name;
}

Or if you use custom filter just adjust value() function as you want.

[macit-emre]

use TD's filterValue() method for loading the right label for your selected filter. no need to override anything.