Laravel checkbox problem which I cannot update the pivot table - laravel

Question

I'm working on a laravel application. In laravel I'm trying to update a row from a pivot table. In this application I have three tables:
issues: id, title, description
categories: id, name
category_issues:(pivot table) id, issue_id, category_id
In laravel I'm trying to update a row from a pivot table. I have this relationships:
Issue.php
public function categories() {
return $this->belongsToMany('App\Category', 'category_issues');
}
Category.php
public function issues() {
return $this->belongsToMany('App\Issue', 'category_issues');
}
A issue can have many categories.
Html code for displaying category section:
<div class="form-group row">
<label for="category" class="col-md-4 col-form-label text-md-right">{{ __('Category :') }}</label>
<div class="form-check col-md-6">
#foreach ($categories as $category)
<input type="checkbox" name="category[]" id="{{ $category->id }}" value="{{ $category->id }}"
{{ in_array($category->id, $issue->categories->pluck('id')->toArray()) ? 'checked' : '' }}>
<label for="{{ $category->id }}"> {{ $category->name }} </label>
#endforeach
</div>
</div>
Here is the update function file:
public function update(Issue $issue)
{
request()->validate([
'title'=> ['required', 'min:3'],
'description'=> ['required', 'min:3'],
'category' => ['required']
]);
$issue->title = request('title');
$issue->description = request('description');
$issue->save();
//Category_Issue Update
$categoryIssue = new CategoryIssue;
$cats = request('category');
foreach ($cats as $cat) {
$categoryIssue->updateOrCreate([
'issue_id'=> $issue->id,
'category_id' => $cat
]);
}
return redirect('issues')->with('success', 'Issue has been updated');
}

Answer 1

Instead of doing the creation / update on the CategoryIssue model (do you even have a CategoryIssue model?), Laravel makes this really easy to update the pivots of a relationship all at once, with the sync() method. You've set up the relationships correctly already per your code above.
In your update() method, you already have your Issue model, and have saved it. You have a set of categories coming in from the form via the $request object (or none if user didn't choose any), so you can then update the pivot like this:
$issue->categories()->sync($request->get('category', []));
Leaving a blank array as the second argument is optional. One small suggestion: maybe make the name of the field on the form 'categories' instead of 'category' just to keep it easy to remember it is an array coming in.