Laravel 属于关系返回 null

Question

I'm building a rudimentary CRM app using Laravel 6.0. Users can freely create accounts, but to get any functionality out of the app, they need to set up a SubscriptionAccount (or join an existing one), which will then allow them to create/manage customer Accounts, add Users, etc. (each is a one to many).

The User model's relationship to SubscriptionAccount model is giving me issues. For example:

$user = User::find(1);
$user->subscription()->create(['name' => 'Test Subscription']);
$user = $user->fresh();
dd($user->subscription); // returns null

I suspected it had to do with the belongsTo relationship in the User model, but the odd thing is that it actually creates and persists a new SubscriptionAccount while using that relationship (second line above), though if you access users relationship from the new SubscriptionAccount it also returns null.

Here are the models:

// User.php
class User
{
    public function subscription()
    {
        return $this->belongsTo(SubscriptionAccount::class, 'subscription_account_id');
    }
}

// SubscriptionAccount.php
class SubscriptionAccount extends Model
{
    public function users()
    {
        return $this->hasMany(User::class, 'subscription_account_id');
    }
}

The only thing out of the ordinary is shortening the name of the relationship to subscription from SubscriptionAccount , but that should have been taken care of by specifying the foreign key in both relationships. Here's the migrations:

Schema::create('subscription_accounts', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->uuid('uuid')->unique();
    $table->string('name');
    $table->timestamps();
});

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->uuid('uuid')->unique();
    $table->bigInteger('subscription_account_id')->unsigned()->index()->nullable();
    $table->string('name');
    ...
    $table->timestamps();
    $table->foreign('subscription_account_id')
        ->references('id')
        ->on('subscription_accounts');
});

If I create the user from a SubscriptionAccount (ie $subscriptionAccount->users()->create([...]); it sets the correct subscription_account_id on the users table, but doesn't work vice versa.

Answer 1

This is a known issue (feature?) with the belongsTo relationship:

https://github.com/laravel/framework/issues/29978

To work around it you can associate the models manually:

$user = User::find(1);
$sub = Subscription::create(['name' => 'Test Subscription']);
$user->subscription()->associate($sub);
$user->save();

Answer 2

So instead of using belongsTo because a subscription account does not belongs to one user, it can belong to many, you might want to use the hasOne relationship instead:

public function subscription()
{
    return $this->hasOne(SubscriptionAccount::class, 'id', 'subscription_account_id');
}

It will belongTo one User if you had a user_id within the subscription_accounts table.

Let me know if it makes sense and if it works:)