基本上，我想解决此错误
在null上调用成员函数comment（）
我正在尝试在我的网站上建立一个系统，以便用户可以发布，查看帖子的评论并进行回复。
例如，当用户在http://127.0.0.1:8000/post/show/6上发表评论时，它应转到http://127.0.0.1:8000/comment/store将评论插入数据库中，然后显示评论
但是
当前发生的情况是，在http://127.0.0.1:8000/post/show/6中输入注释后，它指向http://127.0.0.1:8000/comment/store，并在laravel的PrettyPageHandler上显示此错误：
在null上调用成员函数comment（）
我不知道我在做什么错。
请帮助
这些是我的代码：
PostController.php
<?php
// PostController.php
namespace App\Http\Controllers;
use App\Post;
use Illuminate\Http\Request;
use Auth;
use Stevebauman\Location\Facades\Location;
class PostController extends Controller
{
protected $fillable = [
'Uploader',
];
public function __construct()
{
return $this->middleware('auth');
}
public function create()
{
return view('post');
}
public function store(Request $request)
{
{
$post = new Post;
$post->title = $request->get('title');
$post->type = $request->get('type');
$post->description = $request->get('description');
$post->body = $request->get('body');
$post->UniqueId = str_random(16);
$post->Uploader = Auth::user()->name;
$post->Language = 'en';
$post->Location=Location::get()->countryCode;
$post->views = 0;
$post->Applauds = 0;
$post->Boos = 0;
$post->Tags = "hey";
if ($request->get('agegroup')) {
$post->agegroup = $request->get('agegroup');
} else {
$post->agegroup ='undefined';
}
$post->AllowComments = 'true';
$post->CommentsBg = 'default';
$post->Visibility = 'globally public';
$post->others = 'embeddable';
$post->save();
return redirect('posts');
}
}
public function index()
{
$posts = Post::all();
return view('index', compact('posts'));
}
public function show($id)
{
$post = Post::find($id);
return view('show', compact('post'));
}
}
CommentController.php
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Comment;
use App\Post;
class CommentController extends Controller
{
public function store(Request $request)
{
$comment = new Comment;
$comment->body = $request->get('comment_body');
$comment->user()->associate($request->user());
$post = Post::find($request->get('post_id'));
$post->comments()->save($comment);
return back();
}
}
Web.php
/*
|--------------------------------------------------------------------------
| Web Routes
|--------------------------------------------------------------------------
|
| Here is where you can register web routes for your application. These
| routes are loaded by the RouteServiceProvider within a group which
| contains the "web" middleware group. Now create something great!
|
*/
Route::get('/', function () {
return view('welcome');
});
Auth::routes();
Route::get('logout', '\App\Http\Controllers\Auth\LoginController@logout');
Route::get('/home', 'HomeController@index')->name('home');
Route::get('/admin', 'AdminController@index')->name('admin');
Route::get('/upload', 'UploadController@index')->name('upload');
Route::get('/post/create', 'PostController@create')->name('post.create');
Route::post('/post/store', 'PostController@store')->name('post.store');
Route::get('/posts', 'PostController@index')->name('posts');
Route::get('/post/show/{id}', 'PostController@show')->name('post.show');
Route::post('/comment/store', 'CommentController@store')->name('comment.add');
Route::post('/reply/store', 'CommentController@replyStore')->name('reply.add');
Route::match(['get', 'post'], 'imageupload', 'ImageController@Image');
Route::delete('delimage/{filename}', 'ImageController@Image');
post.blade.php
@extends('layouts.app')
@section('content')
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card">
<div class="card-header">Create Post</div>
<div class="card-body">
<form method="post" action="{{ route('post.store') }}">
<div class="form-group">
@csrf
<label class="label">Post Title: </label>
<input type="text" name="title" class="form-control" required/>
</div>
<label class="label">Post Type </label>
<input type="text" name="type" class="form-control" required/>
<label class="label">Tags </label>
<input type="text" name="tags" class="form-control" required/>
<label class="label">Age-group(optional) </label>
<input type="text" name="agegroup" class="form-control" required/>
<div class="form-group">
<label class="label">Post Description </label>
<textarea name="description" rows="5" cols="20" class="form-control" required></textarea>
</div>
<div class="form-group">
<label class="label">Post Body: </label>
<textarea name="body" rows="10" cols="30" class="form-control" required></textarea>
</div>
<div class="form-group">
<input type="submit" class="btn btn-success" />
</div>
</form>
</div>
</div>
</div>
</div>
</div>
@endsection
show.blade.php
<!-- show.blade.php -->
@extends('layouts.app')
@section('content')
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card">
<div class="card-body">
<p><b>{{ $post->title }}</b></p>
<p>
{{ $post->body }}
</p>
<hr />
<h4>Display Comments</h4>
@foreach($post->comments as $comment)
<div class="display-comment">
<strong>{{ $comment->user->name }}</strong>
<p>{{ $comment->body }}</p>
</div>
@endforeach
<hr />
<h4>Add comment</h4>
<form method="post" action="{{ route('comment.add') }}">
@csrf
<div class="form-group">
<input type="text" name="comment_body" class="form-control" />
<input type="hidden" name="post_id" value="{{ $post->id }}" />
</div>
<div class="form-group">
<input type="submit" class="btn btn-warning" value="Add Comment" />
</div>
</form>
</div>
</div>
</div>
</div>
</div>
@endsection
index.blade.php
@extends('layouts.app')
@section('content')
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<table class="table table-striped">
<thead>
<th>ID</th>
<th>Title</th>
<th>Action</th>
</thead>
<tbody>
@foreach($posts as $post)
<tr>
<td>{{ $post->Id }}</td>
<td>{{ $post->title }}</td>
<td>
<a href="{{ route('post.show', ['id' => $post]) }}" class="btn btn-primary">Show Post</a>
</td>
</tr>
@endforeach
</tbody>
</table>
</div>
</div>
</div>
@endsection
答案 0 :(得分：1)
我想问题出在 CommentController.php 代码的这一部分：
$post = Post::find($request->get('post_id'));
$post->comments()->save($comment);
您的假设是第一行Post::find()返回一个新的Post对象。显然不是。为什么？我不知道，但是可能是因为ID不存在？
您可以通过以下方法进行检查：
$post = Post::find($request->get('post_id'));
if (!is_object($post)) echo "Yeah, I really have a problem here...";
$post->comments()->save($comment);
答案 1 :(得分：0)
嗨，这是因为您没有正确检索输入。.
class CommentController extends Controller
{
public function store(Request $request)
{
$comment = new Comment;
$comment->body = $request->comment_body;
$comment->user()->associate($request->user());
$post = Post::find($request->post_id);
$post->comments()->save($comment);
return back();
}
}
使用$request->get('field_name')代替使用$request->field_name
编辑说明：
您的表单方法是post ..如果该函数存在，您也可以使用$request->post('field_name') ..有很多方法可以检索输入，但是正如我在回答中所写的那样，我使用$request->field_name .. < / p>
为什么会出现此错误，是因为Post :: find（null / undefined）返回null ..
答案 2 :(得分：0)
您遇到此错误是因为当您这样做：
$post = Post::find($request->get('post_id'));
您什么也没找到，因此$ post为空。因此，您应该找出原因。尝试调试并查看$ request-> get（'post_id'）包含的内容。也许它包含错误的帖子ID，或者里面没有任何内容。
如果是这种情况，我认为答案是要做的：
$post = Post::find($request->input('post_id'));
致谢
答案 3 :(得分：0)
我明白了。
我必须将post_id更改为post_Id`，反之亦然，如：
CommentController.php
<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Comment;
use App\Post;
class CommentController extends Controller
{
public function store(Request $request)
{
$comment = new Comment;
$comment->body = $request->comment_body;
$comment->user()->associate($request->user());
$post = Post::find($request->post_id);
$post->comments()->save($comment);
return back();
}
}
在
show.blade.php
<!-- show.blade.php -->
@extends('layouts.app')
@section('content')
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card">
<div class="card-body">
<p><b>{{ $post->title }}</b></p>
<p>
{{ $post->body }}
</p>
<hr />
<h4>Display Comments</h4>
@foreach($post->comments as $comment)
<div class="display-comment">
<strong>{{ $comment->user->name }}</strong>
<p>{{ $comment->body }}</p>
</div>
@endforeach
<hr />
<h4>Add comment</h4>
<form method="post" action="{{ route('comment.add') }}">
@csrf
<div class="form-group">
<input type="text" name="comment_body" class="form-control" />
<input type="hidde" name="post_id" value="{{ $post->Id }}" />
</div>
<div class="form-group">
<input type="submit" class="btn btn-warning" value="Add Comment" />
</div>
</form>
</div>
</div>
</div>
</div>
</div>
@endsection