列重复

Question

我试图为laravel 5.8项目创建外键，但出现错误：

我的迁移文件

    public function up()
    {
        Schema::table('chatter_discussion', function (Blueprint $table) {
            $table->integer('chatter_category_id')->unsigned()->index();
            $table->foreign('chatter_category_id')->references('id')->on('chatter_categories')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
            $table->bigInteger('user_id')->unsigned()->index();
            $table->foreign('user_id')->references('id')->on('users')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
        });
        Schema::table('chatter_post', function (Blueprint $table) {
            $table->integer('chatter_discussion_id')->unsigned()->index();
            $table->foreign('chatter_discussion_id')->references('id')->on('chatter_discussion')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
            $table->bigInteger('user_id')->unsigned()->index();
            $table->foreign('user_id')->references('id')->on('users')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
        });
    }

Answer 1

您只需在模型中定义关系，而无需设置外键等。

https://laravel.com/docs/5.8/eloquent-relationships

因此，在您的ChatterDiscussion / ChatterPost模型（可能必须创建）中，您将具有以下功能：

public function chatter_category()
{
    return $this->hasOne('App\ChatterCategory');
}

在ChatterCategory（可能还需要创建）中，您将得到相反的结果：

public function chatter_discussion()
{
    return $this->belongsTo('App\ChatterDiscussion');
}
public function chatter_post()
{
    return $this->belongsTo('App\ChatterPost');
}

然后，您可以在模型中的每个删除功能中处理删除。

无论哪种方式，您的错误都是您两次创建相同的列名。这样的事情应该可以工作（我还没有测试过）

Schema::table('chatter_discussion', function (Blueprint $table) {
            $table->foreign('chatter_category_id')->unsigned()->index()->references('id')->on('chatter_categories')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
            $table->foreign('user_id')->references('id')->on('users')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
        });
        Schema::table('chatter_post', function (Blueprint $table) {
            $table->foreign('chatter_discussion_id')->unsigned()->index()->references('id')->on('chatter_discussion')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
            $table->foreign('user_id')->references('id')->on('users')
                        ->onDelete('cascade')
                        ->onUpdate('cascade');
        });