Laravel非递归toArray（）

Question

Attempting to do both hasMany() and hasOne() relationships between the two tables as I've done before .

I have an Account model which has both users() (one-to-many) and a superUser() (one-to-one), both of which are stored in the built-in User model. As with normal one-to-many relationships, the "many" table ( users ) stores the relationship to the "one", but for the one-to-one relationship, I'm storing the association in the accounts table.

Accounts:

/* model */
public function superUser()
{
    return $this->hasOne(User::class, 'id', 'superuser_id');
}

public function users()
{
    return $this->hasMany(User::class);
}

/* migration */
public function up()
{
    Schema::create('accounts', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->bigInteger('superuser_id')->unsigned();
        $table->string('name');
        $table->timestamps();

        $table->foreign('superuser_id')
            ->references('id')
            ->on('users')
            ->onDelete('cascade');
    });
}

Users

/* model */
public function account()
{
    return $this->belongsTo(Account::class);
}

/* migration */
public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->bigInteger('account_id')->unsigned()->index()->nullable();
        $table->string('name');
        $table->string('email')->unique();
        $table->timestamp('email_verified_at')->nullable();
        $table->string('password');
        $table->rememberToken();
        $table->timestamps();
    });
}

Testing the relationships

Create a user:

>>> $user = factory(App\User::class)->create()
=> App\User {#3014
     name: "Rose Grant II",
     email: "ernser.thomas@example.com",
     email_verified_at: "2019-05-31 15:38:32",
     updated_at: "2019-05-31 15:38:32",
     created_at: "2019-05-31 15:38:32",
     id: 23,
   }

Create an account with $user as superuser:

>>> $account = factory(App\Account::class)->create(['superuser_id' => $user]);
=> App\Account {#3024
     name: "Kuhic-Price",
     superuser_id: 23,
     updated_at: "2019-05-31 15:39:11",
     created_at: "2019-05-31 15:39:11",
     id: 17,
   }
>>> $account->superUser
=> App\User {#3011
     id: 23,
     account_id: null,
     name: "Rose Grant II",
     email: "ernser.thomas@example.com",
     email_verified_at: "2019-05-31 15:38:32",
     api_token: null,
     created_at: "2019-05-31 15:38:32",
     updated_at: "2019-05-31 15:38:32",
   }

account_id is null because we haven't yet associated $user to the Account :

>>> $account->superUser->account()->associate($account)->save()
=> true
>>> $account->superUser
=> App\User {#3011
     id: 23,
     account_id: 17,
     name: "Rose Grant II",
     email: "ernser.thomas@example.com",
     email_verified_at: "2019-05-31 15:38:32",
     api_token: null,
     created_at: "2019-05-31 15:38:32",
     updated_at: "2019-05-31 15:43:55",
     account: App\Account {#3024
       name: "Kuhic-Price",
       superuser_id: 23,
       updated_at: "2019-05-31 15:39:11",
       created_at: "2019-05-31 15:39:11",
       id: 17,
       superUser: App\User {#3011},
     },
   }

But once we do this, it hangs:

>>> $account->toArray()
^C

I'm thinking that this is due to each model pointing towards the other: the superuser of the Account loads the User which loads the Account ad infinitum. Is this a bug in toArray() or simply normal behavior that I have to watch out for? Or am I doing it wrong?

Answer 1

In the Laravel codebase, toArray() is a convenience function merging the results of attributesToArray() and relationsToArray() into a single merged array :

public function toArray()
{
    return array_merge($this->attributesToArray(), $this->relationsToArray());
}

As I suspected, relationsToArray() calls toArray() on every arrayable relationship, causing the infinite recursion :

public function relationsToArray()
{
    $attributes = [];

    foreach ($this->getArrayableRelations() as $key => $value) {
        // If the values implements the Arrayable interface we can just call this
        // toArray method on the instances which will convert both models and
        // collections to their proper array form and we'll set the values.
        if ($value instanceof Arrayable) {
            $relation = $value->toArray();   // <-- here's the recursive call
        }

    ...

If all that is needed is the attributes (as in my case), calling attributesToArray() on the model is a good workaround:

>>> $account->attributesToArray()
=> [
     "name" => "Kuhic-Price",
     "superuser_id" => 23,
     "updated_at" => "2019-05-31 15:39:11",
     "created_at" => "2019-05-31 15:39:11",
     "id" => 17,
   ]

---

EDIT: Also this behavior is by design, as the documentation explicitly states recursion:

This method is recursive , so all attributes and all relations ( including the relations of relations ) will be converted to arrays (emphasis mine)