Eloquent Relationship with a conditional scope - php

Question

I'm working on a Fantasy sports app. The models I am working with are FantasyPlayer, PlayerGame, TeamGame
FantasyPlayer can have many PlayerGame and can have many TeamGame
public function PlayerGame()
{
return $this->hasMany('App\Models\PlayerGame','player_id','player_id');
}
public function TeamGame()
{
return $this->hasMany('App\Models\FantasyData\TeamGame','team','fantasy_player_key');
}
When I load the data I use eager loading currently:
FantasyPlayer::with(['PlayerGame', 'TeamGame'])->take(1)->get();
It is becoming tedious to load both relationships and then which are loaded. Ideally, I want to have the model handle this logic for. So I would be able to do something like this:
FantasyPlayer::with(['FantasyGame'])->take(1)->get();
Then my FantasyGame scope would contain either the PlayerGame or the TeamGame record I need based on an a FantasyPlayer value for the position. Something like this is what I want... but it doesn't work for me:
public function scopeFantasyGame($query)
{
if($this->position == "DEF"){
return $this->TeamGame();
}
else{
return $this->PlayerGame();
}
}
Does anyone know way I could use eager loading and have the FantasyGame return the correct relationship based on a FantasyPlayer position attribute?:
FantasyPlayer::with(['FantasyGame'])->take(1)->get();

Answer 1

#1
You can't eager load relationships conditionally based on the result elements, this because the eager loading happens before you retrieve the records, that's why this won't work:
# FantasyPlayer.php
public function scopeFantasyGame($query)
{
if($this->position == "DEF") // <--- Laravel doens't retrieve the records yet,
{ // so this won't work
//
}
else
{
//
}
}
#2
Local Query scopes are used to constraint queries, in your case you want to load relationships with this scope, not its general purpose but sure you could do it:
# FantasyPlayer.php
public function scopeFantasyGame($query)
{
return $query->with(['PlayerGame', 'TeamGame']);
}
Then use it like this:
# YourController.php
public function myFunction($query)
{
$fantasyPlayers = FantasyPlayer::fantasyGame()->get();
}
#3
But then, if you want to always eager load the relationships, why use a query scope and not just tell laravel to load your desired relationships by default? You could do specify it in your model (check the Eager Loading By Default of this section of the docs):
# FantasyPlayer.php
protected $with = ['PlayerGame', 'TeamGame'];
Update
If you want to retrieve elements that always have a given relationship, you have two paths. For the first one, you could use a query scope to only load those elements:
# FantasyPlayer.php
public function scopeHasFantasyGame($query)
{
return $query
->has('PlayerGame')
->has('TeamGame');
}
Then:
# YourController.php
public function myFunction($query)
{
$fantasyPlayers = FantasyPlayer::hasFantasyGame()->get();
}
The second option would be to retrieve the elements, then filter the collection based on the existence of the relationship (using the Map() function):
# YourController.php
public function myFunction($query)
{
$fantasyPlayers = FantasyPlayer::all()
->map(function ($fantasyPlayer) {
return $fantasyPlayer->PlayerGame()->exists()
&& $fantasyPlayer->TeamGame()->exists();
});
}