如何使用laravel控制器更新数据库？ MethodNotAllowedHttpException没有消息错误消息

I'm trying to update my database using a form on my edit.blade.php page as shown below. The edit part works correctly as the fields are filled in in the form as expected, however when i try to save, an error message of

Symfony \ Component \ HttpKernel \ Exception \ MethodNotAllowedHttpException No message

is displayed. I have tried so many ways on how to fix it and I'm not sure where I'm going wrong. Hopefully it's something simple to fix?

edit.blade.php

@extends('layouts.app')

    <!-- Styles -->
        <link href="{{ asset('css/app.css') }}" rel="stylesheet">

    @section('content')
    <div class="container">
        <div class="row justify-content-center">
            <div class="col-md-8">


            <form method="post" action="{{ action('PostsController@update', $id) }}">

                {{ csrf_field() }}
                <input type="hidden" name="_method" value="PATCH" />

            <h1>Edit Item</h1>
            <div class="form-group">

                <label for="item">Item:</label>

                <input type="text" id="item" name="item" value="{{$post->item}}" class="form-control" required>

            </div>



            <div class="form-group">

                        <label for="weight">Weight (g):</label>

                        <input type="number" id="weight" value="{{$post->weight}}" name="weight" class="form-control">

            </div>



            <div class="form-group">

                        <label for="noofservings">No of Servings:</label>

                        <input type="number" id="noofservings" value="{{$post->noofservings}}" name="noofservings" class="form-control">

            </div>



            <div class="form-group">

                        <label for="calories">Calories (kcal):</label>

                        <input type="number" id="calories" name="calories" value="{{$post->calories}}" class="form-control">

            </div>



            <div class="form-group">

                        <label for="fat">Fat (g):</label>

                        <input type="number" id="fat" name="fat" value="{{$post->fat}}" class="form-control">

            </div>



            <button type="submit" class="btn btn-primary">Save</button>


        </form>

            </div>
        </div>
    </div>
@endsection

PostsController.php

<?php
public function update(Request $request, $id)
    {

        $this->validate('$request', [

            'item' => 'required'

        ]);

         $post = Post::find($id);
         $post->item = $request->input('item');
         $post->weight = $request->input('weight');
         $post->noofservings = $request->input('noofservings'); 
         $post->calories = $request->input('calories');
         $post->fat = $request->input('fat');
         $post->save();

         return redirect('/foodlog');
    }

web.php

<?php
Route::get('edit/{id}', 'PostsController@edit');

Route::put('/edit', 'PostsController@update');

Post.php

<?php
namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{

    protected $fillable = [

        'id',
        'user_id',
        'item',
        'weight',
        'noofservings', 
        'calories',
        'fat',
        'created_at'
    ]; 

}

My website is a food log application and this function is so that they can edit their log.

Any help is greatly appreciated!