从一对多关系中删除 Laravel

Question

I have the two following models in one to many relationship:

Category.php

public function post()
{
    return $this->hasMany('App\Category', 'category_id');
}

And Post.php

public function category()
{
    return $this->belongsTo('App\Post', 'category_id');
}

1. I delete thee category that has few blog post under it.
2. Open the blog post whose category is deleted
3. Gets error as the category doesn't exist anymore

What is the best way to delete the category without causing the error ? Should I set the category_id of post to null while deleting their category ?

Answer 1

Use withDefault for if any category doesn't exist it'll give you null.

Category.php

public function post()
{
    return $this->hasMany('App\Post', 'category_id')->withDefault();
}

Post.php

public function category()
{
    return $this->belongsTo('App\Category', 'category_id')->withDefault();
}

Answer 2

Maybe this is gonna be the late answer but I will answer for Google searches anyway.

You can handle relationship cascading on the database If you don't want any null error about deleting the models on your project. Write this code to your project table migration.

$table->bigInteger('category_id')->unsigned();
$table->foreign('category_id')->references('id')
      ->on('categories')->onDelete('cascade');