Clash Royale CLAN TAG#URR8PPP

Laravel Cannot delete or update a parent row: a foreign key constraint fails

For some reason a user cannot delete a post if it has been liked, it was working before but when I linked posts with likes I have been getting this error, I can't even delete it in Sequel Pro, unless I delete the likes associated with the post first.

Error

SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or
update a parent row: a foreign key constraint fails
(eliapi8.likes, CONSTRAINT likes_post_id_foreign FOREIGN KEY
(post_id) REFERENCES posts (id)) (SQL: delete from posts where
id = 149)

eliapi8

likes

likes_post_id_foreign

post_id

posts

id

posts

id

Maybe it's my schema?

Posts Schema

Schema::create('posts', function (Blueprint $table)
$table->increments('id');
$table->string('title');
$table->text('body');
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users');
$table->timestamps();
);


Likes Schema

Schema::create('likes', function (Blueprint $table)
$table->increments('id');
$table->integer('post_id')->unsigned();
$table->integer('user_id')->unsigned();
$table->foreign('post_id')->references('id')->on('posts');
$table->foreign('user_id')->references('id')->on('users');
$table->softDeletes();
$table->timestamps();
);


I can like and unlike a post, but a user cannot delete a post that has been liked.

PostController.php

public function destroy(Post $post)

$this->authorize('delete', $post);
$postl = Post::with('likes')->whereId($post)->delete();

if ($post->delete())
if($postl)
return response()->json(['message' => 'deleted']);

;

return response()->json(['error' => 'something went wrong'], 400);



1 Answer
1

Yes, it's your schema. The constraint on likes.post_id will prevent you from deleting records from the posts table.

likes.post_id

posts

One solution could be using onDelete('cascade') in the likes migration file:

onDelete('cascade')

likes

Schema::create('likes', function (Blueprint $table)
// Some other fields...

$table->integer('post_id')->unsigned();
$table->foreign('post_id')->references('id')->on('posts')->onDelete('cascade');
);


This way, when a post is deleted, all related likes will be deleted too.

Or, if you have a relationship from the Post model to the Like model, you can $post->likes()->delete() before deleting the post itself.

$post->likes()->delete()

posts

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