数据库/迁移/2018\u 12\u 20\u 022430\u创建\u产品\u表.php

> class CreateProductsTable extends Migration {
>     /**
>      * Run the migrations.
>      *
>      * @return void
>      */
>     public function up()
>     {
>         Schema::create('products', function (Blueprint $table) {
>             $table->increments('id');
>             $table->string ('name');
>             $table->text('description');
>             $table->decimal('price');
>             $table->string('file');
>             $table->timestamps();
>         });
>     }

数据库/迁移/2018\u 12\u 20\u 042857\u创建\u卡片\u表格.php

class CreateCardsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('cards', function (Blueprint $table) {
            $table->increments('id');
            $table->string ('quantity');
            $table->string('status');
            $table->integer('pid')->unsigned();
            $table->foreign('pid')->references('id')->on('products');
            $table->integer('cid')->unsigned();
            $table->foreign('cid')->references('id')->on('customers');

            $table->timestamps();
        });
    }

数据库/factories/userfactory.php

$factory->define(App\Product::class, function (Faker $faker) { 
    return [
              //'id'=>$faker->numberBetween($min = 1, $max = 20),
              'name'=> $faker->word,
              'description'=> $faker->sentence($nbWords = 6, $variableNbWords = true),
              'price' => $faker->randomFloat($nbMaxDecimals = 100, $min = 1, $max = 10),
              'file' => $faker->imageUrl($width = 640, $height = 480),
    ];
});

$factory->define(App\Card::class, function (Faker $faker) {
    return [
               //'id'=>$faker->numberBetween($min = 1, $max = 20),
               'quantity'=>$faker->sentence($nbWords = 6, $variableNbWords = true),
               'status'=>$faker->boolean($chanceOfGettingTrue = 10),
               'cid'=>$faker->numberBetween($min = 1, $max = 20),
              'pid'=>$faker->numberBetween($min = 1, $max = 20),
    ];
});

路由/web.php

factory(App\Product::class,5)->create();
factory(App\Card::class,5)->create();

终端：

$ php artisan db:seed

错误：
在connection.php第664行中：sqlstate[23000]：完整性约束冲突：1452无法添加或更新子行：外键约束失败( food . cards ，约束 ca rds_pid_foreign 外键( pid )参考文献 products ( id ))（sql:插入） cards ( quantity , status , cid , pid , updated_at , creat ed_at )价值观（简历1，
18, 8, 2019-01-02 04:22:10, 2019-01-02 04:22:10))
在connection.php第458行中：sqlstate[23000]：完整性约束冲突：1452无法添加或更新子行：外键约束失败( food . cards ，约束 ca rds_pid_foreign 外键( pid )参考文献 products ( id ))