尝试阅读属性“标题”在null上

Question

我知道问题是什么，但我无法解决。当我创建具有以下代码的类别时，没问题。但是，当我尝试创建产品时，它不会更新category_id，因此我每次都会遇到此错误。两个控制器的代码相同（产品使用类别控制器的函数）

我的productController.php

<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\Category;
use App\Models\Product;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;

class ProductController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        //
        $data = Product::all();
        return view('admin.product.index', [
            'data' => $data
        ]);
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        $data = Category::all();
        return view('admin.product.create', [
            'data' => $data
        ]);
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        $data = new Product();
        $data->category_id = $request->category_id;
        $data->user_id = 0; // $request->user_id;
        $data->title = $request->title;
        $data->keywords = $request->keywords;
        $data->description = $request->description;
        $data->detail = $request->detail;
        $data->price = $request->price;
        $data->months = $request->months;
        $data->status = $request->status;
        if ($request -> file('image')){
            $data-> image = $request->file('image') -> store('public/images');
        }
        $data->save();
        return redirect('admin/product');
    }

    /**
     * Display the specified resource.
     *
     * @param  \App\Models\Product  $product
     * @return \Illuminate\Http\Response
     */
    public function show(Product $product,$id)
    {
        //
        $data = Product::find($id);
        return view('admin.product.show', [
            'data' => $data
        ]);
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  \App\Models\Product  $product
     * @return \Illuminate\Http\Response
     */
    public function edit(Product $product, $id)
    {
        //
        $data = Product::find($id);
        $datalist = Category::all();
        return view('admin.product.edit', [
            'data' => $data,
            'datalist' => $datalist
        ]);
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \App\Models\Product  $product
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, Product $product, $id)
    {
        //
        $data = Product::find($id);
        $data->category_id = $request->category_id;
        $data->user_id = 0; // $request->user_id;
        $data->title = $request->title;
        $data->keywords = $request->keywords;
        $data->description = $request->description;
        $data->detail = $request->detail;
        $data->price = $request->price;
        $data->months = $request->months;
        $data->status = $request->status;
        if ($request -> file('image')){
            $data-> image = $request->file('image') -> store('public/images');
        }
        $data->save();
        return redirect('admin/product');

    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  \App\Models\Product  $product
     * @return \Illuminate\Http\Response
     */
    public function destroy(Product $product, $id)
    {
        //
        $data = Product::find($id);
        if ($data->image){
            Storage::delete($data->image);
        }
        $data->delete();
        return redirect('admin/product');

    }
}

my categorycontroller.php

<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\Category;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Storage;

class CategoryController extends Controller
{

    protected $appends = [
        'getParentsTree'
    ];

    public static function getParentsTree ($category, $title){

        if ($category->parent_id == 1)
        {
            return $title;
        }
        $parent = Category::find($category->parent_id);
        $title = $parent->title.' > '. $title;
        return CategoryController::getParentsTree ($parent, $title);
    }

    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        //
        $data = Category::all();
        return view('admin.category.index', [
            'data' => $data
        ]);
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        $data = Category::all();
        return view('admin.category.create', [
            'data' => $data
        ]);
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        $data = new Category;
        $data->parent_id = $request->parent_id;
        $data->title = $request->title;
        $data->keywords = $request->keywords;
        $data->description = $request->description;
        $data->status = $request->status;
        if ($request -> file('image')){
            $data-> image = $request->file('image') -> store('public/images');
        }
        $data->save();
        return redirect('admin/category');
    }

    /**
     * Display the specified resource.
     *
     * @param  \App\Models\Category  $category
     * @return \Illuminate\Http\Response
     */
    public function show(Category $category,$id)
    {
        //
        $data = Category::find($id);
        return view('admin.category.show', [
            'data' => $data
        ]);
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  \App\Models\Category  $category
     * @return \Illuminate\Http\Response
     */
    public function edit(Category $category, $id)
    {
        //
        $data = Category::find($id);
        $datalist = Category::all();
        return view('admin.category.edit', [
            'data' => $data,
            'datalist' => $datalist
        ]);
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \App\Models\Category  $category
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, Category $category, $id)
    {
        //
        $data = Category::find($id);
        $data->parent_id = $request->parent_id;
        $data->title = $request->title;
        $data->keywords = $request->keywords;
        $data->description = $request->description;
        $data->status = $request->status;
        if ($request -> file('image')){
            $data-> image = $request->file('image') -> store('public/images');
        }
        $data->save();
        return redirect('admin/category');
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  \App\Models\Category  $category
     * @return \Illuminate\Http\Response
     */
    public function destroy(Category $category, $id)
    {
        //
        $data = Category::find($id);
        if ($data->image){
            Storage::delete($data->image);
        }
        $data->delete();
        return redirect('admin/category');

    }
}

my create.blade.blade.php of Product

@extends('layouts.adminbase')

@section('title', 'Add Product')

@section('content')
    <!-- Begin Page Content -->
    <div class="container-fluid">

        <!-- Page Heading -->
        <h1 class="h3 mb-4 text-gray-800">Add Product</h1>

        <!-- Collapsable Card-->
        <div class="card shadow mb-4">
            <!-- Card Header - Accordion -->
            <a href="#collapseCardExample" class="d-block card-header py-3" data-toggle="collapse"
               role="button" aria-expanded="true" aria-controls="collapseCardExample">
                <h6 class="m-0 font-weight-bold text-primary">Product Elements</h6>
            </a>
            <!-- Card Content - Collapse -->
            <div class="collapse show" id="collapseCardExample">
                <div class="card-body">
                    <form action="{{route('admin_product_store')}}" method="POST" enctype="multipart/form-data">
                        @csrf
                        <div class="card-body">

                            <div class="form-group">
                                <label >Parent Product</label>
                                <select class="form-control select2" name="parent_id" >
                                    @foreach ($data as $rs)
                                        <option value="{{ $rs->id }}"> {{ \App\Http\Controllers\Admin\CategoryController::getParentsTree($rs, $rs->title) }}</option>
                                    @endforeach
                                </select>
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Title</label>
                                <input type="text" class="form-control" name="title" placeholder="Title">
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Keywords</label>
                                <input type="text" class="form-control" name="keywords" placeholder="Keywords">
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Description</label>
                                <input type="text" class="form-control" name="description" placeholder="Description">
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Price</label>
                                <input type="number" class="form-control" name="Price" value="0">
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Months</label>
                                <input type="number" class="form-control" name="Months" value="0">
                            </div>

                            <div class="form-group">
                                <label for="exampleInputEmail1">Detail</label>
                                <textarea class="form-control" name="detail">

                                </textarea>
                            </div>

                            <div class="form-group">
                                <label for="exampleInputFile">Image</label>
                                <div class="input-group">
                                    <div class="custom-file">
                                        <input type="file" class="custom-file-input" name="image">
                                        <label class="custom-file-label" for="exampleInputFile">Choose image file</label>
                                    </div>
                                </div>
                            </div>
                            <div class="form-group">
                                <label>Status</label>
                                <select class="custom-select" name="status">
                                    <option>Enabled</option>
                                    <option>Disabled</option>
                                </select>
                            </div>
                        </div>
                        <!-- /.card-body -->

                        <div class="card-footer">
                            <button type="submit" class="btn btn-primary">Save</button>
                        </div>
                    </form>
                </div>
            </div>
        </div>

    </div>
    <!-- /.container-fluid -->

    </div>
    <!-- End of Main Content -->

@endsection


 

Answer 1

始终在控制器中使用验证，特别是在商店或更新方法中。
通过验证，您可以控制要在服务器端获得哪种数据，并轻松将500个错误（服务器端）更改为400个错误（客户端）。

我强烈建议您在下面的链接中查看有关验证的整个文档：

varrization

laravel 在这种特定情况下，您的问题是您的类别ID，该类别ID在您的类别表中不存在。

我建议您只需在您的cateControler商店方法中使用有关您的category_id的验证，例如：

 public function store(Request $request)
 {
         $validated = $request->validate([
                'category_id' => 'required|exists:categories,id',
         ]);
    
         // Rest of your code 

 }

，请记住在控制器中始终使用验证。
希望对您有帮助。