Automatically deleting related rows in Laravel Eloquent ORM

Question

When I delete a row using this syntax    user- gt delete      Is there a way to attach a callback of sorts  so that it would e g  do this automatically    this- gt photo  - gt delete      Preferably inside the model-class

User · Answer

In my case it was pretty simple because my database tables are InnoDB with foreign keys with Cascade on Delete.

So in this case if your photos table contains a foreign key reference for the user than all you have to do is to delete the hotel and the cleanup will be done by the Data Base, the data base will delete all the photos records from the data base.

User · Answer

You can actually set this up in your migrations    table- gt foreign  user id  - gt references  id  - gt on  users  - gt onDelete  cascade     Source  http   laravel com docs 5 1 migrations foreign-key-constraints     You may also specify the desired action for the  on delete  and  on   update  properties of the constraint    table- gt foreign  user id         - gt references  id  - gt on  users         - gt onDelete  cascade

User · Answer

It is better if you override the delete method for this  That way  you can incorporate DB transactions within the delete method itself  If you use the event way  you will have to cover your call of delete method with a DB transaction every time you call it   In your User model   public function delete          DB  beginTransaction           this         - gt photo           - gt delete               result   parent  delete          DB  commit         return  result

User · Answer

Relation in User model   public function photos         return  this- gt hasMany  Photo        Delete record and related    user   User  find  id       delete related     user- gt photos  - gt delete      user- gt delete

User · Answer

You can use this method as an alternative   What will happen is that we take all the tables associated with the users table and delete the related data using looping   tables   DB  select       SELECT         TABLE NAME          COLUMN NAME          CONSTRAINT NAME          REFERENCED TABLE NAME          REFERENCED COLUMN NAME     FROM INFORMATION SCHEMA KEY COLUMN USAGE     WHERE REFERENCED TABLE NAME    users       foreach  tables as  table        table name     table- gt TABLE NAME       column name    table- gt COLUMN NAME       DB  delete  delete from  table name where  column name         id

User · Answer

I would iterate through the collection detaching everything before deleting the object itself  here s an example  try            user   User  findOrFail  id           if   user- gt has  photos                  foreach   user- gt photos as  photo                      user- gt photos  - gt detach  photo                                    user- gt delete            return  User deleted         catch  Exception  e            dd  e          I know it is not automatic but it is very simple  Another simple approach would be to provide the model with a method  Like this  public function detach           try                            if   this- gt has  photos                      foreach   this- gt photos as  photo                              this- gt photos  - gt detach  photo                                                         catch  Exception  e                dd  e                Then you can simply call this where you need   user- gt detach     user- gt delete

User · Answer

As of Laravel 5 2  the documentation states that these kinds of event handlers should be registered in the AppServiceProvider    lt  php class AppServiceProvider extends ServiceProvider                  Bootstrap any application services                 return void             public function boot                 User  deleting function   user                 user- gt photos  - gt delete                        I even suppose to move them to separate classes instead of closures for better application structure

User · Answer

I believe this is a perfect use-case for Eloquent events  http   laravel com docs eloquent model-events   You can use the  deleting  event to do the cleanup     class User extends Eloquent       public function photos                 return  this- gt has many  Photo                  this is a recommended way to declare event handlers     public static function boot             parent  boot             static  deleting function  user       before delete   method call this               user- gt photos  - gt delete                    do the rest of the cleanup                          You should probably also put the whole thing inside a transaction  to ensure the referential integrity

User · Answer

yeah  but as  supersan stated upper in a comment  if you delete   on a QueryBuilder  the model event will not be fired  because we are not loading the model itself  then calling delete   on that model   The events are fired only if we use the delete function on a Model Instance   So  this beeing said   if user- gt hasMany post  and if post- gt hasMany tags    in order to delete the post tags when deleting the user  we would have to iterate over  user- gt posts and calling  post- gt delete    foreach  user- gt posts as  post     post- gt delete      -  this will fire the deleting event on Post  VS   user- gt posts  - gt delete   -  this will not fire the deleting event on post because we do not actually load the Post Model  we only run a SQL like  DELETE   from posts where user id    user- gt id and thus  the Post model is not even loaded

User · Answer

There are 3 approaches to solving this   1  Using Eloquent Events On Model Boot  ref  https   laravel com docs 5 7 eloquent events   class User extends Eloquent       public static function boot             parent  boot             static  deleting function  user                  user- gt photos  - gt delete                          2  Using Eloquent Event Observers  ref  https   laravel com docs 5 7 eloquent observers   In your AppServiceProvider  register the observer like so   public function boot         User  observe UserObserver  class       Next  add an Observer class like so   class UserObserver       public function deleting User  user                  user- gt photos  - gt delete              3  Using Foreign Key Constraints  ref  https   laravel com docs 5 7 migrations foreign-key-constraints    table- gt foreign  user id  - gt references  id  - gt on  users  - gt onDelete  cascade

User · Answer

To elaborate on the selected answer  if your relationships also have child relationships that must be deleted  you have to retrieve all child relationship records first  then call the delete   method so their delete events are fired properly as well   You can do this easily with higher order messages   class User extends Eloquent                  The  booting  method of the model                 return void             public static function boot             parent  boot             static  deleting function  user                  user- gt photos  - gt get  - gt each- gt delete                          You can also improve performance by querying only the relationships ID column   class User extends Eloquent                  The  booting  method of the model                 return void             public static function boot             parent  boot             static  deleting function  user                  user- gt photos  - gt get   id   - gt each- gt delete

User · Answer

Note  This answer was written for Laravel 3  Thus might or might not works well in more recent version of Laravel    You can delete all related photos before actually deleting the user    lt  php  class User extends Eloquent        public function photos                 return  this- gt has many  Photo               public function delete                    delete all related photos           this- gt photos  - gt delete               as suggested by Dirk in comment             it s an uglier alternative  but faster            Photo  where  user id    this- gt id - gt delete               delete the user         return parent  delete              Hope it helps

User · Answer

Or you can do this if you wanted  just another option   try       DB  connection  - gt pdo- gt beginTransaction          photos   Photo  where  user id         user id - gt delete       Delete all photos for user      user   Geofence  where  id         user id - gt delete       Delete users      DB  connection  - gt pdo- gt commit      catch  Laravel Database Exception  e        DB  connection  - gt pdo- gt rollBack        Log  exception  e       Note if you are not using the default laravel db connection then you need to do the following   DB  connection  connection name  - gt pdo- gt beginTransaction    DB  connection  connection name  - gt pdo- gt commit    DB  connection  connection name  - gt pdo- gt rollBack

[php] Automatically deleting related rows in Laravel (Eloquent ORM)

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