Laravel Eloquent ORM：通过多个一对多的关系获得价值

Question

I have three tables which are users, loans, statuses

The relationship is like this:

A user can have many loans. a loan has many status steps. in the statuses table I have a column called status, basically it telsl this step yes, no. pending sort of situation.

the table structure look like this:

users table
->id
->... 

loans table

->id
->... 
->user_id (it is the foreign key ->references('id')->on('users');

statuses table

->id
->...
->status  (can be "yes", "no", "pending")
->... 
->loan_id (it is the foreign key ->references('id')->on('loans');

the models look like this:

in the User model :

public function loans(){
    return $this->belongsToMany('App\Loan'); 
   }

in the Loan model:

 public function users(){
    return $this->belongsToMany('App\User'); 
   }  
  public function statuses(){
        return $this->hasMany('App\Status');
    }

in the Status model:

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

My question is how to get the status yes number for each user. say I have five users, each user have multiple loans. each loan have, say 20 steps. but different loan many have different yes steps . I would like to use laravel eloquent ORM to get a array tell me each user get how many yes at certain time. So I would be able to loop through this array in my front end blade file to display users progress. thanks!

Answer 1

Laravel's Collection, which you get when you use Eloquent, is great for this kind of operation. Say you want to get the 'yes' statuses of one user:

//yesStatuses is itself a Collection, but it can be used in a foreach like an array
$yesStatuses = $user->loans
  ->map(function ($loan) {
    return $loan->statuses;
  })
  ->filter(function ($status) {
    return $status->status === 'yes';
  });

//Number of statuses === 'yes'
$yesStatuses->count();
//If you need it as a regular array
$yesStatuses->toArray();

When you query your users table you should take care of loading your loans and statuses eagerly, otherwise you'll be performing many queries for this operation. Something like this:

$users = App\User::with('loans.statuses')->get();

More on this:

Eloquent Collections

Eager loading of Eloquent Models