Many to Many relation in Laravel5.4 - php

Question

I Want to Create multi category for posts in database but I Just create one category with this code:
post.php
public function Category()
{
return $this->belongsTo('App\Category');
}
Category.php
public function posts()
{
return $this->belongsToMany('App\Post');
}
posts_table:
public function up()
{
Schema::create('posts', function (Blueprint $table) {
$table->increments('id');
$table->integer('user_id');
$table->integer('category_id');
$table->string('title');
$table->integer('price');
$table->string('description');
$table->timestamps();
});
}
and view for create category is here:
<form method="post" action="/storePost">
{{csrf_field()}}
<input type="hidden" id="user_id" name="user_id" value="
{{Auth::user()->id}}">
<lable>title</lable>
<input type="text" id="title" name="title">
<label>description</label>
<input type="text" id="description" name="description">
<label>price</label>
<input type="text" name="price" id="price">
<label>Category</label>
<select name="category_id">
#foreach($categories as $category)
<option value={{$category->id}}>{{$category->name}}</option>
#endforeach
</select>
<button type="submit" id="AddProduct">add</button>
</form>
And my postcontroller to create category is:
public function store()
{
Post::create([
'user_id'=>request('user_id'),
'title' => request('title'),
'category_id'=>request('category_id'),
'description'=>request('description'),
'price'=>request('price'),
]);
return redirect('/show');
}
How I Can create multi category for one posts in table?

Answer 1

You are going to need to design your database somewhat differently. You need a proper join table between the two tables. Your database should look something like this:
posts
id
//other
categories
id
//other
post_categories
post_id
category_id
Once you have the database setup with a proper join. You have to define the relations a little bit differently:
// App\Models\Post
public function categories() {
return $this->belongsToMany('App\Category', 'post_categories', 'category_id', 'post_id');
}
// App\Models\Category
public function posts() {
return $this->belongsToMany('App\Post', 'post_categories', 'post_id', 'category_id');
}
You can then use attach and detach to add and remove relations:
$post = Post::find(1);
$post->categories()->attach($categoryId);
You can read more about many-to-many relationships in the Laravel Documentation.