attach one to many relationship laravel code example

Example 1: one to many laravel

For example, a blog post may have an infinite number of comments. And a single
comment belongs to only a single post  

class Post extends Model
{
    public function comments()
    {
        return $this->hasMany('App\Models\Comment');
    }
}

class Comment extends Model
{
    public function post()
    {
        return $this->belongsTo('App\Models\Post');
    }
}

Example 2: whereHas site:https://laravel.com/docs/

use Illuminate\Database\Eloquent\Builder;

// Retrieve posts with at least one comment containing words like code%...
$posts = Post::whereHas('comments', function (Builder $query) {
    $query->where('content', 'like', 'code%');
})->get();

// Retrieve posts with at least ten comments containing words like code%...
$posts = Post::whereHas('comments', function (Builder $query) {
    $query->where('content', 'like', 'code%');
}, '>=', 10)->get();

Example 3: add the data inside has many relationship laravel

$post = App\Models\Post::find(1);

$comment = $post->comments()->create([
    'message' => 'A new comment.',
]);

--------------- OR ------------------
  
$post->comments()->createMany([
    [
        'message' => 'A new comment.',
    ],
    [
        'message' => 'Another new comment.',
    ],
]);

Example 4: add data to laravel many to many relationship

1. $user->roles()->attach($roleId);

2. you may also pass an array of additional data to be inserted 
$user->roles()->attach($roleId, ['expires' => $expires]);

3. // Detach a single role from the user...
$user->roles()->detach($roleId);

4. // Detach all roles from the user...
$user->roles()->detach();

5. Any IDs that are not in the given array will be removed from the intermediate
	table
$user->roles()->sync([1, 2, 3]);

6. If you need to update an existing row in your pivot table, you may use 
  updateExistingPivot method. This method accepts the pivot record foreign 
  key and an array of attributes to update:

$user->roles()->updateExistingPivot($roleId, $attributes);