如何修复laravel迁移中的外键错误

Question

我有一个订单表，我之前创建了这个表，但有时我必须更改我的迁移。

这是我更改前的订单表：

Schema::create('orders', function (Blueprint $table) {
        $table->id();

        $table->unsignedBigInteger('user_id');
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

        $table->bigInteger('price');
        $table->enum('status', ['unpaid', 'paid', 'preparation', 'posted', 'recieved', 'canceled']);
        $table->string('tracking_serial')->nullable();

        $table->timestamps();
    });

    Schema::create('order_product', function (Blueprint $table) {
        $table->unsignedBigInteger('product_id');
        $table->foreign('product_id')->references('id')->on('products')->onDelete('cascade');

        $table->unsignedBigInteger('order_id');
        $table->foreign('order_id')->references('id')->on('orders')->onDelete('cascade');

        $table->integer('quantity');

        $table->primary(['product_id', 'order_id']);
    });

这是更改后的订单表：

Schema::create('orders', function (Blueprint $table) {
        $table->id();

        $table->unsignedBigInteger('user_id');
        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

        $table->unsignedBigInteger('address_id');
        $table->foreign('address_id')->references('id')->on('addresses')->onDelete('cascade');

        $table->bigInteger('price');
        $table->string('post_type');
        $table->enum('status', ['unpaid', 'paid', 'preparation', 'posted', 'recieved', 'canceled']);
        $table->string('tracking_serial')->nullable();

        $table->primary(['user_id', 'address_id']);

        $table->timestamps();
    });

    Schema::create('order_product', function (Blueprint $table) {
        $table->unsignedBigInteger('product_id');
        $table->foreign('product_id')->references('id')->on('products')->onDelete('cascade');

        $table->unsignedBigInteger('order_id');
        $table->foreign('order_id')->references('id')->on('orders')->onDelete('cascade');

        $table->integer('quantity');

        $table->primary(['product_id', 'order_id']);
    });

如您所见，我在 orders 架构中导入了 3 条新行：

$table->unsignedBigInteger('address_id');
$table->foreign('address_id')->references('id')->on('addresses')->onDelete('cascade');

$table->string('post_type');

$table->primary(['user_id', 'address_id']);

但是当我想运行 php artisan migrate 时，我得到了这个错误：

SQLSTATE[HY000]: General error: 1005 Can't create table `shop`.`orders` (errno: 150 "Foreign key 
constraint is incorrectly formed") (SQL: alter table `orders` add constraint 
`orders_address_id_foreign` foreign key (`address_id`) references `addresses` (`id`) on delete 
cascade)

为什么会出现这个错误？

更新：

这是我的地址表：

Schema::create('addresses', function (Blueprint $table) {
        $table->id();
        $table->string('state');
        $table->string('city');
        $table->text('address');
        $table->integer('plaque');
        $table->string('postal');
        $table->timestamps();
    });

    Schema::create('address_user', function (Blueprint $table) {
        $table->id();

        $table->unsignedBigInteger('user_id');
        $table->foreign('user_id')->references('id')->on('users')
        ->onDelete('cascade');
        $table->unsignedBigInteger('address_id');
        $table->foreign('address_id')->references('id')->on('addresses')
        ->onDelete('cascade');
        $table->primary(['user_id', 'address_id']);

        $table->timestamps();
    });

并在地址之前进行顺序迁移。

Answer 1

我希望您使用迁移来更改订单表，而不仅仅是修改原始迁移？

这个错误的发生通常有几个原因：

1. fk 字段（address_id）和 pk 字段（即地址）不是同一类型
2. 订单迁移在地址表之前运行（我认为在这种情况下不太可能，因为错误会有所不同）
3. address_id 不可为空（据我所知），因此当您创建 FK 时，当前存在的行将没有有效的 FK 来寻址。 （所以让它可以为空）

Answer 2

必须先创建表，再创建外键：

Schema::create('orders', function (Blueprint $table) {
        $table->id();
        $table->unsignedBigInteger('user_id');
        $table->unsignedBigInteger('address_id');
        $table->bigInteger('price');
        $table->string('post_type');
        $table->enum('status',['unpaid','paid','preparation','posted', 'recieved', 'canceled']);
        $table->string('tracking_serial')->nullable();
        $table->primary(['user_id', 'address_id']);
        $table->timestamps();
    });


Schema::table('orders', function (Blueprint $table) {

        $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
        $table->foreign('address_id')->references('id')->on('addresses')->onDelete('cascade');
    });