Set key to difference key when get laravel relationship - php

Question

I want to change my collection array key to language code.
Here is my code
$products = Product::has('languages')->paginate(20);
return response()->json($products);
This is my relationship
public function languages($lang_id = null)
{
if ($lang_id)
return $this->hasMany(ProductLang::class)->where('lang_id', $lang_id)->first();
return $this->hasMany(ProductLang::class);
}
This is what I get for now.
Illuminate\Database\Eloquent\Collection {#613 ▼
#items: array:2 [▼
0 => App\Models\Product\ProductLang {#614 ▶}
1 => App\Models\Product\ProductLang {#615 ▶}
]
}
Expected:
Illuminate\Database\Eloquent\Collection {#613 ▼
#items: array:2 [▼
en => App\Models\Product\ProductLang {#614 ▶}
zh => App\Models\Product\ProductLang {#615 ▶}
]
}
Thanks for any help..

Answer 1

There is a collection method called keyBy. Also, I woudn't use a conditional parameter in a relationship the way you pass $lang_id. I'd rather create two relationship methods.
So, you can do:
$products = Product::has('languages')
->paginate(20)
->getCollection()
->map(function ($product) {
return $product->languages->keyBy('lang_id');
});
return response()->json($products);

Answer 2

You could try and remap the key of the loaded relationship after the query like so:
$products = Product::has('languages')->paginate(20);
foreach($products as $product){
$product->setRelation('languages', $product->languages->mapWithKeys(function($language){
// Assuming the code is in the attribute `language_code`
return [$language->language_code => $language];
}));
}
return response()->json($products);

Answer 3

You can use mapWithKeys collection method.
As per Laravel Documentation:
The mapWithKeys method iterates through the collection and passes each
value to the given callback. The callback should return an associative
array containing a single key / value pair:
$keyed = $products->mapWithKeys(function ($item) {
return [$item['locale'] => $item]; // assuming 'locale' key
});
$keyed->all();
References:
Laravel -> Collections -> Method mapwithkeys
Laracast -> Change eloquent model relationship key