在laravel中使用外键迁移时出错

Posted 2023-03-14

【中文标题】在laravel中使用外键迁移时出错

【英文标题】：error while migrating with foreign key in laravel

【发布时间】：2021-02-21 00:59:11

【问题描述】：

我正在尝试迁移下面的函数，但每次都给我同样的错误，我找不到原因，即使我尝试了文档中的其他语法

//向上函数

public function up()
    
        Schema::create('categories', function (Blueprint $table) 
            $table->id('cat_id');
            $table->string('cat_name');
            $table->string('cat_desc');
            $table->string('cat_image');
            $table->timestamps();
        );



Schema::create('sellers', function (Blueprint $table) 
        $table->id('seller_id');
        $table->string('seller_name');
        $table->string('seller_desc');
        $table->string('seller_image');
        $table->timestamps();
    );

    Schema::create('products', function (Blueprint $table) 
        $table->id('prd_id');
        $table->string('prd_name');
        $table->string('prd_price');
        $table->string('prd_image');
        $table->string('prd_desc');
        $table->foreignId('product_cat_id')->constrained('categories');
        $table->foreignId('product_seller_id')->constrained('sellers');
        $table->boolean('prd_status');
        $table->timestamps();
    );

//错误

SQLSTATE[HY000]：一般错误：1005 无法创建表 ecommerce.products (errno: 150 "外键约束不正确 形成”）（SQL：改变表产品添加约束 products_product_cat_id_foreign 外键 (product_cat_id) 参考类别 (id))

我也从数据库中删除了迁移文件并进行了新的迁移，但没有帮助，请指导我，提前谢谢

【问题讨论】：

如果您有自定义 ID 名称，请使用更详细的声明 > $table->foreign('user_id')->references('id')->on('users');

【参考方案1】：

public function up()
    
        Schema::create('categories', function (Blueprint $table) 
            $table->increments('id');
            $table->integer('cat_id')->unsigned();
            $table->string('cat_name');
            $table->string('cat_desc');
            $table->string('cat_image');
            $table->timestamps();
        );



Schema::create('sellers', function (Blueprint $table) 
        $table->increments('id');
        $table->integer('seller_id')->unsigned();
        $table->string('seller_name');
        $table->string('seller_desc');
        $table->string('seller_image');
        $table->timestamps();
    );

    Schema::create('products', function (Blueprint $table) 
        $table->increments('id');
        $table->integer('prd_id')->unsigned();
        $table->string('prd_name');
        $table->string('prd_price');
        $table->string('prd_image');
        $table->string('prd_desc');
        $table->foreignId('product_cat_id')->constrained('categories');
        $table->foreignId('product_seller_id')->constrained('sellers');
        $table->boolean('prd_status');
        $table->timestamps();
    );

【参考方案2】：

这是因为，在您的categories 和sellers 两个表中，主键 都不是id，默认情况下constrained 方法使用@987654326 @ 作为主键作为外键引用，所以改变：

$table->foreignId('product_cat_id')->constrained('categories');
$table->foreignId('product_seller_id')->constrained('sellers');

到，

$table->unsignedBigInteger('product_cat_id');
$table->foreign('product_cat_id')->references('cat_id')->on('categories');

$table->unsignedBigInteger('product_seller_id');
$table->foreign('product_seller_id')->references('seller_id')->on('sellers');

如果您使用的是模型，那么还要在您的模型上定义您的 primary key，例如：

protected $primaryKey = 'cat_id';