create list for dropdown with value from relationed table - laravel

Question

My model Product return something like this
id = 1
name = Product Name
category_id = 101
category = array
id = 101
name = electronics
and I need to use lists() to create something like this:
lists("category.name", "id")
but it looks that this is impossible. How to create list for dropdown like this:
1 = electronics
2 = furniture
3 = cars
...
thanks a lot

Answer 1

Are you sure you did set up the right relations? Cause that is just what lists() usually does and it's far from impossible to create such a list.
It's quite hard to understand how you did design your Eloquent logic without your code, but here's how I would handle your situation, assuming you've already set up the category_product pivot table.
Given two models, Product and Category, I'd define these 2 relations cause, as far as I can get, a product can have several categories and a categories can be associated with several product :
class Product extends Model
{
////////
public function categories()
{
return $this->belongsToMany('App\Category');
}
////////
}
and
class Category extends Model
{
////////
public function products()
{
return $this->belongsToMany('App\Product');
}
////////
}
At this point, you're good to go, all you have to do in order to get your list is
Product::findOrFail($id)->categories->lists('name','id')
This will return an array holding all the categories associated with the given product
array:[
1 => first-category
2 => second-category
3 => third-category
....
]
Note that with this set up it'll work the other way around as well, if you want to get a list of all the product that match a given category
Category::findOrFail($id)->products->lists('name','id')
At the very top of the answer I assumed you did set up a pivot table but, if you didn't, here's a quick tip:
within your products migration
public function up()
{
Schema::create('products', function (Blueprint $table) {
//
});
Schema::create('category_product', function (Blueprint $table){
$table->integer('category_id')->unsigned()->index();
$table->foreign('category_id')->references('id')->on('categories')->onDelete('cascade');
$table->integer('product_id')->unsigned()->index();
$table->foreign('product_id')->references('id')->on('products')->onDelete('cascade');
$table->timestamps();
});
}
Then migrate and now everything is properly set up. Last but not least, if you are going to use this migration, you'll need to fix the relation in the model, which one is up to yours app logic: let's say the flow is create a new product -> choose the categories within the creation form, then you need to add timestamps() in the categories method
return $this->belongsToMany('App\Category')->withTimeStamps();