How to define Laravel relationship when multiple columns are associated

Question

I have models just like I have mentioned below, How laravel eloquent-relationship can be implemented on it?

User Model

id
name

Post Model

id
title
desc
created_by = foreign key on User->id

Stage One (PostStageOneModel)

id
post_id
assigned_by
assigned_to

Stage Two (PostStageTwoModel)

post_id
assigned_by  = foreign key on User->id
assigned_to  = foreign key on User->id

Stage Three (PostStageThreeModel)

post_id
assigned_by  = foreign key on User->id
assigned_to  = foreign key on User->id

Stage Four (PostStageFourModel)

post_id
assigned_by  = foreign key on User->id
assigned_to  = foreign key on User->id

Stage Five (PostStageFiveModel)

post_id
assigned_by  = foreign key on User->id
assigned_to  = foreign key on User->id

Stage Six (PostStageSixModel)

post_id
assigned_by  = foreign key on User->id
assigned_to  = foreign key on User->id

Answer 1

Relationships can specify which column they use:

public function assigner(){
    return $this->belongsTo(User::class, 'assigned_by');
}
public function assignee(){
    return $this->belongsTo(User::class, 'assigned_to');
}

Answer 2

User model should have an hasMany relationship type like below:

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class User extends Model {
    //...
    public function posts() {
        return $this->hasMany(Post::class);
    }
}

Posts belongs to Users via created_by attribute

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Post extends Model {
    //...
    public function createdBy() {
        return $this->belongsTo(User::class, 'created_by');
    }
}

PostStageOneModel belongs to posts and to users using 2 different attributes

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class PostStageOneModel extends Model {
    //...
    public function post() {
        return $this->belongsTo(Post::class);
    }
    public function assignedTo() {
        return $this->belongsTo(User::class, 'assigned_to');
    }
    public function assignedBy() {
        return $this->belongsTo(User::class, 'assigned_by');
    }
}

hope this help

Answer 3

I did it by defining following relations

In PostStageOneModel model

public function assignedPost() {
    return $this->belongsTo(Post::class, 'post_id', 'post_id');
}

public function assigner()
{
    return $this->belongsTo(User::class, 'assigned_by', 'id');
}

public function assignee()
{
    return $this->belongsTo(User::class, 'assigned_to', 'id');
}

In Post Model

public function identifiedBy() {
    return $this->belongsTo(User::class, 'identified_by', 'id');
}

public function postAssignedBy() {
    return $this->hasManyThrough(User::class, PostStageOneModel::class, 'post_id', 'id', 'post_id', 'assigned_by' );
}

public function postAssignedTo() {
    return $this->hasManyThrough(User::class, PostStageOneModel::class, 'post_id', 'id', 'post_id', 'assigned_to' );
}

In User Model

public function assigned()
{
    return $this->hasMany(PostStageOneModel::class, 'assigned_by', 'id');
}

public function assignedTo()
{
    return $this->hasMany(PostStageOneModel::class, 'assigned_to', 'id');
}