->dependsOn in MorphTo doesn't provide access to the polymorphic relation's type, only its ID

[jlevers]

• Laravel Version: 10.25.2
• Nova Version: 4.27.13
• PHP Version: 8.2.11
• Database Driver & Version: PostgresSQL 15.4
• Operating System and Version: Ubuntu 22.04.3
• Browser type and version: Brave 1.58
• Reproduction Repository: N/A

Description:

When using ->dependsOn with a MorphTo field, the MorphTo attribute in FormData doesn't allow me to access the polymorphic relation's class – only its ID. This was reported in #4518, and marked as fixed, but I'm still running into this problem now.

Detailed steps to reproduce the issue on a fresh Nova installation:

With this fields method on a Status resource:

/**
 * Get the fields displayed by the resource.
 *
 * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
 * @return array
 */
public function fields(NovaRequest $request)
{
    return [
        MorphTo::make('Statusable')->types([
            Listing::class,
            Order::class,
        ]),

        Select::make('Status')
            ->dependsOn(
                'statusable',
                function (Select $field, NovaRequest $request, FormData $formData)
                {
                    logger()->debug($formData->statusable);
                    return $field;
                }
            ),
    ];
}

The only thing that will be logged by the logger()->debug($formData->statusable) line is a model ID, so it's impossible to retrieve the polymorphic relationship by the $formData information alone.

I've hacked around this by accessing the static $model attribute on MorphTo::morphToResource as shown below, but this definitely doesn't feel like the right way to it:

/**
 * Get the fields displayed by the resource.
 *
 * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
 * @return array
 */
public function fields(NovaRequest $request)
{
    $morphTo = MorphTo::make('Statusable')->types([
        Listing::class,
        Order::class,
    ]);

    return [
        $morphTo,

        Select::make('Status')
            ->dependsOn(
                'statusable',
                function (Select $field, NovaRequest $request, FormData $formData) use ($morphTo)
                {
                    logger()->debug($morphTo->morphToResource::$model);
                    return $field;
                }
            ),
    ];
}

Thanks! Let me know if more info is needed.

[jlevers]

For anyone else encountering this, I found a more reliable workaround for my particular use case, which is attaching statuses to various resources via those resources' detail pages:

public function fields(NovaRequest $request)
{
    return [
        MorphTo::make('Statusable')->types([
            Listing::class,
            Order::class,
        ]),

        Select::make('Status')
            ->dependsOn(
                'statusable',
                function (Select $field, NovaRequest $request, FormData $formData)
                {
                    $resourceKey = $request->viaResource;
                    $resourceId = $request->viaResourceId;  // In case you need it for something...I did
                    $resourceCls = Laravel\Nova\Nova::resourceForKey($resourceKey);
                    logger()->debug($resourceCls::$model);
                    return $field;
                }
            ),
    ];
}

[crynobone]

You can use the following:

    return [
-        MorphTo::make('Statusable')->types([
+        $statusable = MorphTo::make('Statusable')->types([
            Listing::class,
            Order::class,
        ]),

        Select::make('Status')
            ->dependsOn(
-               'statusable',
+               $statusable,
                function (Select $field, NovaRequest $request, FormData $formData)
                {
-                   logger()->debug($formData->statusable);
+                   logger()->debug($formData->statusable_type);
                    return $field;
                }
            ),
    ];