Can't send collection to bootstrap-select in Laravel form - php

Question

Here is an edit form I've created
#extends('main')
#section('title', 'Edit Post')
#section('content')
<form class="form-group" action="/categories/update" method="POST">
{{csrf_field()}}
<input name="_method" type="hidden" value="PUT">
<label for="category_id" id="category_id">Select Category</label>
<select class="form-control" id="category_id" style="height:auto;" name="category_id">
#foreach($categories as $category)
<hr class="custom-hr-heading"/>
<option value="{{$category->id}}" {{($category->id == $post->category->id)?"selected='selected'":""}}>
{{$category->name}}
</option>
#endforeach
</select>
<label for="title" class="mt-2" name="title" id="title">Your Post Title</label>
<input type="text" class="form-control mb-2" value="{{$post->title}}" name="title" id="title">
<textarea class="form-control" name="body">{{$post->body}}</textarea>
<label for="tags" id="tags" name="tags">Select Tags..</label>
<select class="selectpicker mt-3" id="tags[]" name="tags[]" multiple="multiple">
#foreach($tags as$tag)
<option value="{{$tag->id}}">{{$tag->name}}</option>
#endforeach
</select>
<br/>
<button type="submit" class="btn mt-3 btn-success btn-sm">Update</button>
</form>
<script type="text/javascript">
tinymce.init({
selector: 'textarea',
theme: 'modern',
height: 300
});
$('.selectpicker').selectpicker({
style: 'btn-info'
});
</script>
#stop
Controller
public function edit($id)
{
$post = Post::find($id);
$categories = Category::orderBy('name', 'asc')->get();
$tags = Tag::orderBy('name', 'asc')->get();
return view('posts.edit', compact('post', 'categories', 'tags'))
}
I get a themed select box that just says nothing selected. Am I passing the tags collection to the select box correctly?
I'm using Laravel 5.5, PHP 7.2, and Bootstrap 4.
I've tried bootstrap-select via CDN and local files.

Answer 1

You are missing a space
Change:
#foreach($tags as$tag)
To:
#foreach($tags as $tag)

Answer 2

As per Bootstrap 4's documentation, this is a short attribute, not a name-value pair, so I would do it like so (and clean it up a little):
<select class="form-control" id="category_id" style="height:auto;" name="category_id">
<option value="">Choose an Option</option>
#foreach($categories as $category)
<hr class="custom-hr-heading"/>
<option value="{{ $category->id }}" #if($category->id == $post->category->id) selected #endif >
{{ $category->name }}
</option>
#endforeach
</select>

Answer 3

The problem was infact two problems.
Bootstrap 4 (final) support is only available in the latest bootstrap-select beta release here
Also my code was a little out. Here is the final working code.
<select class="selectpicker mt-3 form-control" name="tags[]" multiple>
#foreach($tags as $tag)
<option value="{{$tag->id}}" {{$post->tags->contains($tag->id)?"selected='selected":""}}>{{$tag->name}}</option>
#endforeach
</select>