Laravel Eloquent Many to Many Relationship pivot table-CodePudding

I have three tables categories, film_categories and films and three models respectively Category, FilmCategory and Film.

I have seen many tutorials where they don't create a pivot table model like i have created FilmCategory Model . They just create a pivot table film_categories without a model.

My question is what is the best practise - ?

Should i create a FilmCategory model and set a hasMany relationship

class Film extends Model
 {
     use HasFactory;

    protected $primaryKey = 'film_id';

    /**
     * Film film Relationship 
     * 
     * @return Illuminate\Database\Eloquent\Relations\HasMany
     */
    public function categories()
    {
        return  $this->hasMany(FilmCategory::class, 'film_id', 'film_id');
    }

}

Should i just create a pivot table film_categories without a model FilmCategory and set belongsToMany relationship

class Film extends Model
{
    use HasFactory;

    protected $primaryKey = 'film_id';

    /**
     * Film film Relationship 
     * 
     * @return Illuminate\Database\Eloquent\Relations\HasMany
     */
    public function categoriesWithPivot()
    {
        return  $this->belongsToMany(Category::class, 'film_categories', 'film_id', 'category_id');
    }
}

CodePudding user response：

Technically speaking, both option are fine. You can implement the two of them, and depends on what you want to implement/achieve in the logic part of the code, use one between the two that suits best. Here are things to consider:

First, depends on what is film_categories table used for. If the table is simply exists to relate films and categories tables using many-to-many relationship, then there's no need to create the FilmCategory model, and you can just use belongsToMany(). Otherwise, if the film_categories will relates to another table, then you should create FilmCategory model and define the relation using hasMany(). You're also likely need to add a primary-key field to film_categories if this is the case.

The second consideration to take is what kind of data structure you want to have. Using the codes that you provide, you can get Films using these 2 queries and it'll gives you the correct values but with different structures:

Film::with('categoriesWithPivot')->get();
// Each record will have `Film`, `Category`, and its pivot of `film_categories` table

// OR

// Assuming that `FilmCategory` model has `belongsTo` relation to `Category` ...
Film::with('categories', 'categories.category')->get();
// Will gives you the same content-values as the above, but with in a different structure

And that's it. The first point is mostly more important to consider than the second. But the choice is completely yours. I hope this helps.

CodePudding user response：

Since the film_categories table does not represent an entity in your system, I think you should define a belongsToMany relationship and should not create a separate model for the pivot table. If You still wanna have a model for your pivot table so create a model that extends Illuminate\Database\Eloquent\Relations\Pivot class. Check documentation here: model for pivot table