"Trying to get property 'id' of non-object (View: C:\xampp\htdocs\CERCAA\resources\views\admin\posts\edit.blade.php)" - laravel-5

Question

When I am editing my post then I am prompted with the following error message
Trying to get property 'id' of non-object (View: C:\xampp\htdocs\CERCAA\resources\views\admin\posts\edit.blade.php)
public function update(Request $request, $id)
{
$this->validate($request, [
'title' => 'required',
'content' => 'required',
'category_id' => 'required'
]);
$post = Post::find($id);
if($request->hasFile('featured'))
{
$featured = $request->featured;
$featured_new_name = time() . $featured->getClientOriginalName();
$featured->move('uploads/posts', $featured_new_name);
$post->featured = 'uploads/posts/'.$featured_new_name;
}
$post->title = $request->title;
$post->content = $request->content;
$post->category_id = $request->category_id;
$post->save();
Session::flash('success', 'Post updated successfully.');
return redirect()->route('posts');
}
and blade code
<div class="form-group">
Select a Category
#foreach($categories as $category)
id}}"
#if($post->$category->id == $category->name)
selected
#endif
{{$category->name}}
#endforeach
List item

Answer 1

My Post method for post and category
namespace App;
use Illuminate\Database\Eloquent\Model;
class Category extends Model
{
protected $table = 'categories'; // here set table's name
protected $primaryKey = 'id'; // here set table's primary Key field name
protected $fillable = ['id']; // here set all table's fields name
public function posts()
{
return $this->hasMany('App\Post');
}
namespace App;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
class Post extends Model
{
public function category()
{
return $this->belongsTo('App/Category');
}
public function getFeaturedAttribute($featured)
{
return asset($featured);
}
use SoftDeletes;
protected $dates=['deleted_at'];
protected $fillable=['title','content','category_id','featured','slug'];
}
}

Answer 2

Edit.blade.php
#extends('layouts.app')
#section('content')
<div class="row">
<div class="col-lg-12">
<div class="card">
<div class="card-header bg-info">
<div class="text-center">
<h4 class="m-b-0 text-white">
<div class="panel panel-default">
<div class="panel-heading">
Edit Post:{{$post->title}}
</div>
<div class="panel-body">
<form action="{{route('post.update', ['id'=>$post->id])}} " method="post" enctype="multipart/form-data">
{{csrf_field()}}
<div class="form-group">
<label for ="title">Title</label>
<input type="text" name="title" class="form-control" value="{{$post->title}}">
</div>
<div class="form-group">
<label for ="featured">Featured image</label> <input type="file" name="featured" class="form-control">
</div>
<div class="form-group">
<label for ="category">Select a Category</label>
<select name="category_id" id="category" class="form-control">
#foreach($categories as $category)
<option value="{{$category->id}}"
#if(property_exists($post, 'category') && $post->$category['id'] == $category->name)
selected
#endif
>{{$category->name}}</option>
#endforeach
</select>
</div>
<div class="form-group">
<label for ="content">Content</label>
<textarea name="content" id="content" cols="5" rows="5" class="form-control"> {{$post->content}}</textarea>
</div>
<div class="form-group">
<div class="text-center">
<button class="btn btn-success" type="submit"> Update Post</button>
</div>
</div>
</form>
</div>
</div>
</h4>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<!-- Row -->
#stop

Answer 3

Controller...
public function store(Request $request)
{
$this->validate($request, [
'title' =>'required',
'featured'=>'required|mimes:jpeg,pdf,docx,png:5000',
'file'=>'required|mimes:jpeg,pdf,docx,png:5000',
'content'=>'required',
'category_id'=>'required',
]);
$featured= $request->featured;
$featured_new_name=time().$featured->getClientOriginalName();
$featured->move('uploads/posts', $featured_new_name);
$file=$request->file;
$file_name=time().$file->getClientOriginalName();
$file->move('uploads/posts', $file_name);
$post = Post::create([
'title'=>$request->title,
'content'=>$request->content,
'featured'=>'uploads/posts/'. $featured_new_name,
'file'=>'uploads/posts'. $file_name,
'category_id'=>$request->category_id,
'slug'=>str_slug($request->title)
]);
Session::flash('success', 'New Blog has been Published on Website for Particular Menu');
return redirect()->back();
}

Answer 4

This the area in your blade where you are getting the issue:
<label for ="category">Select a Category</label>
<select name="category_id" id="category" class="form-control">
#foreach($categories as $category)
<option value="{{$category->id}}"
#if(property_exists($post, 'category') && $post->$category['id'] == $category->name)
selected
#endif
>{{$category->name}}</option>
#endforeach
</select>
Where are you fetching and providing $categories to this blade template? I mean the controller method which loads the edit blade?
Can you post that code as well?
And please update your question instead of posting answers.