有多个表的belongsToMany（设计建议）

Question

I have 5 tables in my laravel/vue project:

• Movies
• Series
• Anime
• Actors
• Actors relationship

Actors' table belongs to Movies, Series, Anime and this many-to-many relationship is registered in the actors_relationship .

I'm able to create a many-to-many relationship in the Actor.php model using the following code:

public function movies() {
    return $this->belongsToMany(MovieModel::class, "actors_relationship", 'actor_id', 'media_id')->wherePivot("media_type", AdminHelper::TYPE_MOVIES['value'])->withTimestamps();
}

Using this code I'm getting the records with the included actor id and has a specific int as a media_type .

Until this point, I have no problem. My problem is getting the count of all of these relationships. eg getting the count of movies, series, anime and sorting it desc/asc

Solutions:

1. Retrieving the relationship actors' count from movies, series, anime and register it in a custom attribute . The sorting will be on the client-end.

2. Doing a hard code check on the server-side for the sorting, then checking if the sort is by total_count , if yes, then get the collection first and after the ->get() command, try sorting by the custom attribute .

I would like to follow the best practice regarding this issue. Is there a way to get the count of all relationships and sort by it?

A client-side solution would cause more work because this project will be for Android and Web and therefore will require various modifications in both fields.

Furthermore, I would normally do ->with('movies') and then sort the automatically created field movies_count . I would like to have a similar approach.

Tables:

actors :

id actor_title

movies :

id movie_title 

series :

id series_title 

anime :

id anime_title

actors_relationship :

id actor_id media_id media_type

EDIT:

I'm looking for the best advice to implement a total count of movies , series and anime . This means that I would like the total count of these 3 relations in one field. I could use a custom attribute, but then I will need to sort that using PHP/client-side instead of doing it in the SQL query in Eloquent.

This means that I'm looking for the best way that follows the best practices. The total_count will sum up the total of those aforementioned relations. I would like to sort by this new total_count .

Answer 1

This seems like a good case for a MorphToMany https://laravel.com/docs/5.8/eloquent-relationships#many-to-many-polymorphic-relations

    class Actor

    public function movies()
        {
            return $this->morphedByMany(MovieModel::class,'media',"actors_relationship");
        }

/// Add a the count to the query 

    public function scopeWithRelationsCount($q)
    {
        /// this is needed to so we keep the select of all the table columns too
        if(!$q->getQuery()->columns){
            $q->select($this->getTable().'.*');
        }

        return $q->selectSub(

                ActorRelationship::selectRaw('count(*)')->whereColumn('actor_id', 'actors.id'),

                'relations_count' /// the alias we are using could be anything  
            )
    }

Then you if you want the total number of series, movies and and anime for each actor ordered by most you can use. Actor::withRelationsCount()->orderBy('relations')->get()

There are some macros that make this look a little nicer. Take a look at https://github.com/reinink/advanced-eloquent .