class Lesson extends Mannequin
{
    public operate content material()
    {
        return $this->morphTo();
    }
}

Schema::create('classes', operate (Blueprint $desk) {
    $table->id();
    $table->unsignedBigInteger('channel_id');
    $table->string('title');
    $table->nullableMorphs('content material');
    $table->timestamps();

    $table->international('channel_id')->references('id')->on('channels')->onDelete('cascade');
});

Schema::create('movies', operate (Blueprint $desk) {
    $table->id();
    $table->string('title');
    $table->string('dimension');
    $table->string('path');
    $table->timestamps();
});

Schema::create('articles', operate (Blueprint $desk) {
    $table->id();
    $table->string('physique');
    $table->string('reading_time');
    $table->timestamps();
});

A lesson can have a Video or an Article as a content material, now every little thing works effective, However I’m having a hassle in choosing particular fields whereas keen loading the content material.

Channel::whereId($channelId)->with(['lessons'=> function ($query) {
    $query->with('content:id,size');
}])->first();

Since Lesson content material might be Video or an Article an error shall be proven:

Column not discovered: 1054 Unknown column 'dimension' in 'area record' (SQL: choose `id`, `dimension` from `articles` the place `articles`.`id` in (168))

How can I the fields I need whereas keen loading based mostly on the polymorphic relation kind?