Search for relationship fails with a 404 when a MorphTo field when it's added to a Pivot

[danutavadanei]

• Laravel Version: v8.83.27
• Nova Version: v4.19.5
• PHP Version: 8.1.13
• Database Driver & Version: MySQL 8.0
• Operating System and Version: Docker PHP FPM 8.1
• Browser type and version: Firefox Latest
• Reproduction Repository: https://github.com/###/###

Description:

I have a relationship defined in a Pivot model. I then add it as a field to the nova relationship. When I try to search in the interface for a related model it fails with a 404.

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

Have two basic models:

<?php

namespace App\Models;

use App\Models\Pivots\CampaignProfile;
use Illuminate\Database\Eloquent\Model;
class Campaign extends Model
{
    protected $guarded = [];

    public function profiles(): BelongsToMany
    {
        return $this->belongsToMany(Profile::class)
            ->using(CampaignProfile::class);
    }
}

<?php

namespace App\Models;

use App\Models\Pivots\CampaignProfile;
use Illuminate\Database\Eloquent\Model;
class Profile extends Model
{
    protected $guarded = [];

    public function campaigns(): BelongsToMany
    {
        return $this->belongsToMany(Campaign::class)
            ->using(CampaignProfile::class);
    }
}

Add a pivot model:

<?php

namespace App\Models\Pivots;

use Illuminate\Database\Eloquent\Relations\Pivot;
use Illuminate\Database\Eloquent\Relations\MorphTo;

class CampaignProfile extends Pivot
{
    public $incrementing = true;

    public function participant(): MorphTo
    {
        return $this->morphTo(__FUNCTION__, 'participant_type', 'participant_id');
    }
}

In any of the two resources, define the field with the pivot relationship:

<?php

namespace App\Nova;

use Laravel\Nova\Fields\ID;
use Laravel\Nova\Fields\MorphTo;
use Laravel\Nova\Fields\BelongsToMany;
use Illuminate\Database\Eloquent\Model;
use Laravel\Nova\Http\Requests\NovaRequest;

class Campaign extends Resource
{
    /**
     * The model the resource corresponds to.
     *
     * @var class-string<\App\Models\Campaign>
     */
    public static $model = \App\Models\Campaign::class;

    /**
     * The single value that should be used to represent the resource when being displayed.
     *
     * @var string
     */
    public static $title = 'id';

    /**
     * The columns that should be searched.
     *
     * @var array
     */
    public static $search = [
        'id',
    ];

    /**
     * Get the fields displayed by the resource.
     *
     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
     * @return array
     */
    public function fields(NovaRequest $request)
    {
        return [
            ID::make()->sortable(),

            BelongsToMany::make('Profiles')->fields(function () {
                return [
                    MorphTo::make('Participant')->types([
                        User::class,
                        Team::class,
                    ])->required()->searchable(),
                ];
            }),
        ];
    }

    /**
     * Get the cards available for the request.
     *
     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
     * @return array
     */
    public function cards(NovaRequest $request)
    {
        return [];
    }

    /**
     * Get the filters available for the resource.
     *
     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
     * @return array
     */
    public function filters(NovaRequest $request)
    {
        return [];
    }

    /**
     * Get the lenses available for the resource.
     *
     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
     * @return array
     */
    public function lenses(NovaRequest $request)
    {
        return [];
    }

    /**
     * Get the actions available for the resource.
     *
     * @param  \Laravel\Nova\Http\Requests\NovaRequest  $request
     * @return array
     */
    public function actions(NovaRequest $request)
    {
        return [];
    }
}

I have resources for both User and Team and I used the MorphTo field before (not behind a pivot).

The error is:

[crynobone]

This usage is never supported. There no "Resource" from pivot perspective to query those information and Eloquent "Many-to-Many" relationship doesn't natively support nested relationship.