Laravel get conversation where users in array - php

Question

I am making a messaging app, and i need to check if a conversation already exists that has a certain list of users (no more, no less). I have this model:
class Conversation{
public function users(){
return $this->belongsToMany('App\User');
}
public function messages(){
return $this->hasMany('App\Message');
}
}
I have these tables:
conversations:
id
user_id <- the owner of the conversation
users:
id
email
password
conversation_user:
id
conversation_id
user_id
I want to make a post request like this:
{
"users": [1,4,6], <- user ids
"message": "Some message"
}
If a conversation already exists with all and only users 1,4,6, the message should be added to that conversation to avoid having duplicate conversations in the database. Otherwise i will make a new conversation with the specified users.
This is the best i have been able to do so far:
$existing_conversation = $user->conversations()->whereHas('users',
function($query) use ($data){
$query->whereIn('user_id', $data['users']);
}
)->has('users', '=', count($data['users']));
But it just returns the conversations that has exactly the amount of users that was in the users array. It ignores the inner query..
Does anyone have an idea for this? :)

Answer 1

You can try the following query
$existing_conversation = $user->conversations()->wherePivotIn('user_id', $data['users'])->has('users', count($data['users'])->get();
Haven't tested, should work I think.
UPDATE
Not a very elegant solution, however it works. You can add some helper methods in your controller like
//Get user's conversations with no of users equal to count($data['users']);
protected function get_conversations_with_equal_users(User $user, array $user_ids)
{
return $user->conversations()
->wherePivotIn('user_id', $user_ids)
->has('users', '=', count($user_ids))
->get();
}
//Get the id of a user conversation with exactly same users as $data['users'] if it exists otherwise it will return 0;
protected function get_existing_conversation_id(User $user, array $user_ids)
{
$existing_conversation_id = 0;
$user_conversations_with_equal_users = $this->get_conversations_with_equal_users($user, $user_ids);
foreach($user_conversations_with_equal_users as $conv)
{
$ids = [];
foreach($conv->users as $user)
{
$ids[] = $user->id;
}
if($this->array_equal($user_ids, $ids))
{
$existing_conversation_id = $conv->id;
}
}
return $existing_conversation_id;
}
//Function to compare two arrays for equality.
protected function array_equal($a, $b) {
return (
is_array($a) && is_array($b) &&
count($a) == count($b) &&
array_diff($a, $b) === array_diff($b, $a)
);
}
The you can use the following in your controller to get the existing conversation for user (if it exists)
$existing_conversation_id = $this->get_existing_conversation_id($user, $data['users']);
if($existing_conversation_id)
{
$existing_conversation = Conversation::with('users')
->whereId($existing_conversation_id)
->get();
}