Laravel inserting data as many-to-many and getting error - php

Question

In my application design i each category should be have one or multiple user which i should associate them together, this middle category should be have category_id referenced with categories table and user_id referenced with users table. now i have this migration files:
User:
Schema::create('users', function (Blueprint $table) {
$table->id();
$table->foreignId('user_id')->nullable()->constrained();
$table->boolean('active')->default(0); //activating account in register
$table->string('name')->nullable();
$table->string('family')->nullable();
$table->string('username')->unique();
$table->string('email')->unique();
$table->timestamp('email_verified_at')->index()->nullable();
$table->string('password');
$table->rememberToken();
$table->softDeletes();
$table->timestamp('created_at')->useCurrent();
$table->timestamp('updated_at')->useCurrent();
});
categories:
Schema::create('categories', function (Blueprint $table) {
$table->id();
$table->unsignedBigInteger('parent_id')->nullable();
$table->string('title');
$table->timestamp('created_at')->useCurrent();
$table->timestamp('updated_at')->useCurrent();
});
user_category:
Schema::create('user_category', function (Blueprint $table) {
$table->foreignId('category_id')->constrained()->onDelete('cascade');
$table->foreignId('user_id')->constrained()->onDelete('cascade');
$table->primary(
[
'category_id',
'user_id'
]
);
});
running migrate command work fine and i don't get any error, now i want to create a category and then created category should be referenced with user_category table with attach:
$category = \App\Models\Category::create(
[
'title' => 'php',
]
);
$category->owner()->attach(
[
'user_id' => 1
]
);
here i get this error:
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'category_user_id' in 'field list'
(SQL: insert into `user_category`
(`category_id`, `category_user_id`) values (4, 1))
my Models:
category:
public function owner(): BelongsToMany
{
return $this->belongsToMany(CategoryUser::class );
}
user_category:
public function category(): BelongsToMany
{
return $this->belongsToMany(Category::class);
}

Answer 1

Laravel's naming convention for pivot tables is snake_cased model names in alphabetical order separated by an underscore.
So if you are to follow the conventions, the user_category table should be category_user instead.
Also, the relationships should be in plural form for many-to-many relations.
// Category model
public function users(): BelongsToMany
{
return $this->belongsToMany(User::class);
}
// User model
public function categories(): BelongsToMany
{
return $this->belongsToMany(Category::class);
}
If you are however deviating from the conventions, you can also set it up by customizing the relationships like so:
// Category model
public function owner(): BelongsToMany
{
return $this->belongsToMany(User::class, 'user_category', 'category_id', 'user_id');
}
// User model
public function category(): BelongsToMany
{
return $this->belongsToMany(Category::class, 'user_category', 'user_id', 'category_id');
}