Laravel从外键获取数据

I have two table one is called Submission one called AssignSubmission

Submission belongTo AssignSubmission

public function assignsubmission()
{
    return $this->belongsTo('App\AssignSubmission');
}

AssignSubmissionhasManySubmission

public function submissions()
{
    return $this->hasMany('App\Submission');
}

They are linked with foreign keys In AssignSubmission has id, user_id and submission_id the foreign key is submission_id. In Submission table, it has id, user_id and file, url etc

in AssignSubmission submission_id -> links to -> Submission id. I have assigned different submission to 2 users.

How can I get data from the foreign key? I want to display the url or file in the view

If you have a Submission object $submission already,

$submission->assignSubmission->url will give you the url.

It converts to camalCase for property name.

If you are using laravel relation. Then you can do this: (assuming that your submission table model is named Submission

App\Submission::with('assignsubmission')->get();

I think your relationships might be backwards?

Submission:

public function assignSubmissions()
{
    return $this->hasMany(AssignSubmission::class);
}

AssignSubmission:

public function submission()
{
    return $this->belongsTo(Submission::class);
}

You have written the wrong relationship, It should be like this Submission:

public function assignSubmissions()
    {
        return $this->hasMany('App\Submission');

    }

AssignSubmission:

public function submission()
     {
             return $this->belongsTo('App\AssignSubmission');
     }

To get the results,i am considering Submission and AssignSubmissions is your models, so you can fetch like,

$submission = App\Submission::find(1)->assignSubmissions; 
$assignSubmissions = App\AssignSubmissions::find(1)->submission;

Check this link for more reference https://laravel.com/docs/5.7/eloquent-relationships#one-to-many

You should try this:

Submissions Model

public function assignsubmission()
{
    return $this->hasMany('App\AssignSubmission');
}

AssignSubmission Model

public function submissions()
{
    return $this->belongsTo('App\Submission','submission_id');
}