在laravel中的数据库中播种时出错答案

【问题标题】：error while seeding in database in laravel在laravel中的数据库中播种时出错
【发布时间】：2016-01-22 03:59:38
【问题描述】：

我正在做我的第一个 laravel 项目。我在我的数据库中创建了两个表并尝试在每个表中播种数据。第一个表（项目）的数据按预期插入，但第二个表中没有插入数据（任务）。当我运行php artisan db:seed command 时，出现以下错误。

"完整性约束违规：1062 重复条目 '1' 用于键初级

可能是什么原因，我该如何解决？

这是我的扩展迁移课程

public function up()
{ 
    // 
    Schema::create('projects', function(Blueprint $table)
    {
        $table->increments('id');
        $table->string('name')->default('');            
        $table->string('slug')->default('');            
        $table->timestamps();
    });

    Schema::create('tasks', function(Blueprint $table) {            

       $table->increments('id');            
     //  $table->integer('project_id')->unsigned()->default(0);         
       $table->foreign('project_id')->references('id')->on('projects')->onDelete('cascade');            
       $table->string('name')->default('');         
       $table->string('slug')->default('');         
       $table->boolean('completed')->default(false);            
       $table->text('description')->default('');            
       $table->timestamps();    

    });
}

项目表的种子类

class projectSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        //
        $projects = array(
            ['id' => 1, 'name' => 'Project 1', 'slug' => 'project-1', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 2, 'name' => 'Project 2', 'slug' => 'project-2', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 3, 'name' => 'Project 3', 'slug' => 'project-3', 'created_at' => new DateTime, 'updated_at' => new DateTime]
        );

        // Uncomment the below to run the seeder
        DB::table('projects')->insert($projects);
    }
}

对于任务表：

    public function run()
    {
        //
           $tasks = array(
            ['id' => 1, 'name' => 'Task 1', 'slug' => 'task-1', 'project_id' => 1, 'completed' => false, 'description' => 'My first task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 2, 'name' => 'Task 2', 'slug' => 'task-2', 'project_id' => 1, 'completed' => false, 'description' => 'My first task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 3, 'name' => 'Task 3', 'slug' => 'task-3', 'project_id' => 1, 'completed' => false, 'description' => 'My first task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 4, 'name' => 'Task 4', 'slug' => 'task-4', 'project_id' => 1, 'completed' => true, 'description' => 'My second task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 5, 'name' => 'Task 5', 'slug' => 'task-5', 'project_id' => 1, 'completed' => true, 'description' => 'My third task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 6, 'name' => 'Task 6', 'slug' => 'task-6', 'project_id' => 2, 'completed' => true, 'description' => 'My fourth task', 'created_at' => new DateTime, 'updated_at' => new DateTime],
            ['id' => 7, 'name' => 'Task 7', 'slug' => 'task-7', 'project_id' => 2, 'completed' => false, 'description' => 'My fifth task', 'created_at' => new DateTime, 'updated_at' => new DateTime]
        );

        //// Uncomment the below to run the seeder
        DB::table('tasks')->insert($tasks);
    }
}

【问题讨论】：

这两个表的迁移情况如何？
博文中增加了扩展迁移类。
您是第一次运行脚本吗？检查数据库中的表。

标签： php mysql laravel

【解决方案1】：

两个表的id 列都设置为自动递增，因此只需将其从您插入的数组中删除即可。因为表中可能还有其他条目具有相同的id，所以只需要让MySQL处理id这一代即可。

如果您想确保表只包含您想要播种的值，您可以清空每个播种类中的表：

...
DB::table('projects')->truncate();
DB::table('projects')->insert($projects);

和

...
DB::table('tasks')->truncate();
DB::table('tasks')->insert($tasks);

这样可以确保没有旧条目会因为重复的 id 值而导致违反约束。

【讨论】：