深入理解 Laravel 表单验证与 302 重定向

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Models\UsrsItem; // 假设您的模型是 UsrsItem

class ItemController extends Controller
{
    /**
     * 处理新商品创建请求。
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\RedirectResponse|\Illuminate\Http\Response
     */
    public function new_item(Request $request)
    {
        // 如果验证失败，Laravel 会自动重定向回上一个页面，并闪存错误和旧输入
        $validated = $request->validate([
            'item_name'  => 'required|string|min:4|max:90',
            // 'item_desc'  => 'string|min:4|max:90', // 您的表单中没有这个字段，注意与验证规则保持一致
            'item_price' => 'required|integer|min:4',
        ]);

        // 验证成功后，继续处理业务逻辑
        UsrsItem::create([
            'item_name'  => $validated['item_name'], // 使用数组访问
            'item_price' => $validated['item_price'],
        ]);

        // 重定向到成功页面或返回其他响应
        return redirect()->route('dashboard')->with('success', '商品已成功添加！');
    }
}

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Facades\Validator; // 引入 Validator Facade
use App\Models\UsrsItem;

class ItemController extends Controller
{
    /**
     * 处理新商品创建请求（API 风格）。
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\JsonResponse
     */
    public function new_item_api(Request $request)
    {
        $validator = Validator::make($request->all(), [
            'item_name'  => 'required|string|min:4|max:90',
            'item_price' => 'required|integer|min:4',
        ]);

        if ($validator->fails()) {
            // 验证失败，返回 JSON 格式的错误信息
            return response()->json(['errors' => $validator->errors()], 422); // 422 Unprocessable Entity
        }

        // 验证成功，继续处理业务逻辑
        UsrsItem::create([
            'item_name'  => $request->item_name, // 此时可以直接从 $request 获取
            'item_price' => $request->item_price,
        ]);

        return response()->json(['success' => '商品已成功添加'], 201); // 201 Created
    }
}

<form action="{{ route('newitem') }}" method="post">
    @csrf

    {{-- 全局错误消息显示 --}}
    @if ($errors->any())
        <div class="alert alert-danger">
            <ul>
                @foreach ($errors->all() as $error)
                    <li>{{ $error }}</li>
                @endforeach
            </ul>
        </div>
    @endif

    <div class="mb-3">
        <label for="item_name" class="form-label">商品名称</label>
        <input type="text" class="form-control @error('item_name') is-invalid @enderror" 
               id="item_name" name="item_name" value="{{ old('item_name') }}">
        @error('item_name')
            <div class="invalid-feedback">
                {{ $message }}
            </div>
        @enderror
    </div>

    <div class="mb-3">
        <label for="item_price" class="form-label">价格</label>
        <input type="number" class="form-control @error('item_price') is-invalid @enderror" 
               id="item_price" name="item_price" value="{{ old('item_price') }}">
        @error('item_price')
            <div class="invalid-feedback">
                {{ $message }}
            </div>
        @enderror
    </div>

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