Laravel 模型和关系

Question

我尝试在用户和债券之间建立关系。一张债券总是包含两个用户（债务人、债权人）。

最后，如果我调用$bond->debtor 或$bond->creditor，我想获得一个用户模型

用户模型：

public function bonds()
{
    return $this->hasMany(Bond::class);
}

债券模型：

protected $fillable = ['description', 'amount', 'debtor_id', 'creditor_id'];

public function debtor()
{
    return $this->belongsToMany(User::class, 'bond_user', 'debtor_id', 'user_id');
}

public function creditor()
{
    return $this->belongsToMany(User::class, 'bond_user', 'creditor_id', 'user_id');
}

还有两个迁移：

Schema::create('bonds', function (Blueprint $table) {
        $table->increments('id');
        $table->text('description');
        $table->float('amount', 8, 2);
        $table->integer('debtor_id');
        $table->integer('creditor_id');
        $table->timestamps();
    });

Schema::create('bond_user', function (Blueprint $table) {
        $table->increments('id');
        $table->integer('user_id');
        $table->integer('debtor_id');
        $table->integer('creditor_id');
        $table->timestamps();
    });

每当我打电话时，例如。 $bond->debtor我得到一个整数而不是用户模型。

---

更新

我找到了解决办法：

用户模型：

public function bond_debtor()
{
    return $this->hasMany(Bond::class, 'debtor_id');
}

public function bond_creditor()
{
    return $this->hasMany(Bond::class, 'creditor_id');
}

债券模型：

public function debtor()
{
    return $this->belongsTo(User::class, 'debtor_id');
}

public function creditor()
{
    return $this->belongsTo(User::class, 'creditor_id');
}

Answer 1

设置关系时，需要

1. 设置引用列的字段类型为integer和unsigned

   $table->integer('debtor_id')->unsigned();
   $table->integer('creditor_id')->unsigned();
   

2. 用foreignTable方法设置关系：

   $table->foreign('debtor_id')
       ->references('id')->on('user');
   $table->foreign('creditor_id')
       ->references('id')->on('user');