How use conditional relationship in eloquent laravel - laravel

Question

I have a 'conversation_message' table and separate sender role by column 'sender_type' (admin/user). Both of admin & user in a different table. But when I call the model, that showed error Call to a member function addEagerConstraints() on null
Table column and data
| id | id_group | id_reply | id_sender | sender_type | message
| 1 | 1 | null | 3 | admin | Hi, I'm admin
| 2 | 1 | 1 | 3 | admin | I wanna give u promo
| 3 | 1 | 2 | 18 | user | What's promo ?
I've tried if conditional with column value, but it doesn't work.
Conversation_message.php
public function sender(){
switch($this->sender_type){
case "user":
return $this->belongsTo(User::class, 'id_sender', 'id');
case "admin":
return $this->belongsTo(Admin::class, 'id_sender', 'id');
default:
return;
}
}
InboxController.php
public function message_detail_chat($groupId){
$data = [];
$data['messages'] = Conversation_message::with('replies')
->with('sender')
->with('recipients')
->where(['id_group' => $groupId])->get();
}
I expect to use conditional model by column value 'sender_type' but the actual output is wrong.

Answer 1

laravel provide query scope your can read it from here https://laravel.com/docs/5.8/eloquent#local-scopes
function userSender(){
$this->belongsTo(User::class, 'id_sender', 'id');
}
function adminSender(){
return $this->belongsTo(Admin::class, 'id_sender', 'id');
}
public function scopeSender($query)
{
return $query
->when($this->sender_type === 'user',function($q){
return $q->with('userSender');
})
->when($this->sender_type === 'admin',function($q){
return $q->with('adminSender');
});
}
Now you can access your Sender like this
Conversation_message::Sender()->first();
This should give you the right Sender. Hope it helps.