[Feature Request] add support for `morphTo` inside `relationship` field

Feature Request

What’s the feature you think Backpack should have?

Ability to define a relationship field for a morphTo relationship. Take the examples we’ve just added to the demo (Petshop). You can assign Comments to Pets and Owners… but if you create a CRUD for comments… the closest you can get (by default) is this:

But this isn’t really helpful to the admin. As a dev, you have to

• manually create a select for commentable_type, showing “Pet” and “Owner”
• create a custom field commentable_id that will show either Pets or Owners, depending on what’s selected in commentable_type

I think we should add a new field to relationship, let’s call it relationship.morphTo or something. This new field would show (on the same line):

• a select for the commentable_type
• a select2 for the commentable_id (when type is changed, the options inside this one are changed too)

As a developer, how would you use this? Most of the time you’d just need to define

CRUD::field('commentable')->models([
            \App\Models\Pet::class,            
            \App\Models\Owner::class,
]);

Behind the scenes, it will use that relationship.morphTo field we talked about, which will setup two subfields:

• commentable_type (a simple select)
• commentable_id (a custom select2, let’s call this one relationship.morphTo_select for now, for clarity)

So what it will ACTUALLY DO is the same thing as if the dev defined:

CRUD::field('commentable')->morphTypeField([
        'name' => 'commentable_type',
        'type' => 'select',
        'options' => [
            'App\Models\Pet' => 'Pet',
            'App\Models\Owner' => 'Owner',
        ],
    ])->morphIdField([
        'name' => 'commentable_id',
        'type' => 'relationship.morphTo_select',
        'models' => [
            \App\Models\Pet::class,            
            \App\Models\Owner::class,
        ]
    ]);

The idea behind the above is to:

• make zero changes to the Backpack core;
• add relationship.morphTo and relationship.morphToId fields;
• when the commentable_type select is changed, commentable_id will have its options changed using JS that is stored inside the relationship.morphTo_select field;
• if the dev wants to make the second select work with AJAX, they can replace it with a relationship.morphTo_fetch field (which will switch the AJAX URL it points to);

Have you already implemented a prototype solution, for your own project?

No

Do you see this as a core feature or an add-on?

Core, but not urgent.

[stevebeyatte]

+1

[tabacitu]

Let’s close this in favor of https://github.com/Laravel-Backpack/CRUD/pull/4579 - moving the conversation there as we’re suuuper close to merging it 🎉