为什么我收到此错误？ “未定义变量：表”，“C:\....数据库\迁移\2020_08_25_082835_create_featured_products_table.php”，[]）

Question

我正在使用 mysql 数据库在 laravel 中开发。

这是我得到的错误。

Illuminate\Foundation\Bootstrap\HandleExceptions::handleError("未定义变量：表", "C:\xampp\htdocs\bizzcomputer\database\migrations\2020_08_25_082835_create_featured_products_table.php", [])

此产品表

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class CreateProductsTable extends Migration
{
 
    public function up()
    {
        Schema::create('products', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('prod_name');
            $table->string('prod_brand')->nullable();
            $table->unsignedBigInteger('category_id');
            $table->timestamps();
    
            $table->foreign('category_id')
                ->references('id')
                ->on('categories')
                ->onDelete('cascade');
        });
    }

    public function down()
    {
        Schema::dropIfExists('products');
    }
}

此特色产品表

<?php
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class CreateFeaturedProductsTable extends Migration
{       
    public function up()
    {
        
        Schema::create("featured_products", function($table) {
            $table->increments('id');
            $table->integer('product_id');
            $table->timestamps();
        });

        $table->foreign('product_id')
            ->references('id')
            ->on('products')
            ->onDelete('cascade');

        DB::unprepared('ALTER TABLE `featured_products` DROP PRIMARY KEY, ADD PRIMARY KEY (  `id` ,  `product_id` )');

    }  
    public function down()
    {
        Schema::dropIfExists('featured_products');
    }
}

这有什么问题？ 是否可以使用外键和复合键？

Answer 1

$table 未定义，因为您的外键定义是在 Schema::create() 上下文之外编码的。

所以像这样把它移回里面

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class CreateFeaturedProductsTable extends Migration
{
    public function up()
    {

        Schema::create("featured_products", function ($table) {
            $table->increments('id');
            $table->bigInteger('product_id');
            $table->timestamps();
            $table->foreign('product_id')
                ->references('id')
                ->on('products')
                ->onDelete('cascade');

        });

            DB::unprepared('ALTER TABLE `featured_products` DROP PRIMARY KEY, ADD PRIMARY KEY (  `id` ,  `product_id` )');

    }
    public function down()
    {
        Schema::dropIfExists('featured_products');
    }
}