How to query Eloquent relational tables based on json ids - php

Question

I have a articles table with a field named article_categories.
I have a categories table with id field.
In my Article Model I have defined:
public function category(){
return $this->hasMany(Category::class,'id','article_categories');
}
the categories in the articles table are saved as json like ["1","3","24"]
in my ArticleController I want to retrieve all categories of a specific article.
In my edit function in the ArticleController I have this function:
public function edit(Article $article)
{
$category_ids = implode(',',json_decode($article->article_categories)) ; //this gives me 1,3,24
/////////
// HERE SHOULD COME THE QUERY WHICH I DON'T KNOW
// $article_categories = ??????????
////////
$categories = Category::all();
return view('article.edit', compact('articles','categories','article_categories'));
}
From what I've researched, there is no way to do this with Laravel but I don't know if this is true or not. I'm using Laravel 8.
Can anyone help me?

Answer 1

First of all you should know that you violated a many-to-many relation in a single column and that's not valid. What you should do is a pivot table article_category or category_article and in both Article and Category models you will define a many-to-many relation
like so
class Article extends Model
{
public function categories()
{
return $this->belongsToMany(Category::class);
}
}
class Category extends Model
{
public function articles()
{
return $this->belongsToMany(Article::class);
}
}
And in your controller you can do
public function edit(Article $article)
{
$categories = Category::all();
return view('article.edit', compact('article','categories'));
}
And in the view you will have direct access to $article->categories
In your current situation you can do this
public function edit(Article $article)
{
$category_ids = json_decode($article->article_categories)
$article_categories = Category::whereIn('id', $category_ids);
$categories = Category::all();
return view('article.edit', compact('article','categories','article_categories'));
}