How do I prevent Laravel from stripping original constraints on certain relationships in `has` queries?

In Laravel 7 I have a User model with a hasMany relationship (roles). Throughout the application I can access the User model with auth()->user(), and I can access the roles relationship with auth()->user()->roles.

The roles relationship looks similar to this,

public function roles()
{
    return $this->hasMany(Role::class, 'role_id', 'role_id');
}

I have a Controller that is using Eloquent's whereHas to collect some data. Inside the callback provided to the whereHas I am calling auth()->user()->roles. When I make that call, however, Laravel is removing the original constraints on the roles relationship (where users.role_id = roles.role_id).

This behavior appears to be very intentional in Laravel (looking at HasOneOrMany::addConstraints and Relation::noConstraints in the Laravel Framework 7.x branch).

What can I do to prevent the stripping of original constraints for some relationships inside the has relationship calls?

Snapey

4 years ago

Level 122

I'm puzzled by your relationship. Your user model cannot 'have many' roles with a single role_id column?

If your user has many roles and presumably a role can have many users then you should have a role_user table with user_id and role_id columns

Your models User and Role should have belongsToMany() relationships.

wpharding

4 years ago

Level 1

Thanks for the response @snapey!

Here is an example set of data demonstrating, but regardless I don't think it changes the core question.

Users

| id | role_id | 
| ------------ |
| 1  |   45    |
| 2  |   46    |

Roles

| id | role_id | 
| ------------ |
| 1  |   45    |
| 2  |   45    |
| 3  |   46    |
| 4  |   46    |

Our data is not quite structured like this, but I was attempting to simplify - obviously I failed. The core question, however, relates to what Laravel is doing here:

https://github.com/laravel/framework/blob/7.x/src/Illuminate/Database/Eloquent/Relations/HasOneOrMany.php#L84

and here:

https://github.com/laravel/framework/blob/7.x/src/Illuminate/Database/Eloquent/Relations/Relation.php#L80

Inside of a whereHas block Laravel is removing the initial constraints on all relationship instances (the $constraints variable is static). I'm curious what I can do to prevent it from happening on certain relationships (like my calls to auth()->user()->roles within the whereHas).

Changing my roles() relationship to look like this fixes it within the whereHas block, but then adds a redundant constraint for all uses outside of the whereHas block.

public function roles()
{
    return $this->hasMany(Role::class, 'role_id', 'role_id')->where('role_id', $this->role_id);
}

Thanks again for the response, let me know if I can clarify further.

mrlohi

4 years ago

Level 1

we may chain additional constraints on this posts relationship: you to define a default model that will be returned if the given relationship is null regards ghd

wpharding

4 years ago

Level 1

Thanks for the thoughts @mrlohi, but in this case the problem isn't that the relationship is returning null. Rather, it is returning far more data than it should since it no longer has the original constraints (i.e. where users.role_id = roles.role_id).

Please or to participate in this conversation.