通过laravel雄辩模型获取联接三表中的特定值

我有三张桌子

Mail_Settings_Line_types table
 id
 mail_line_type

其中邮件行类型的值可以为“body”“subject”“greeting”

其中，邮件行可以有“亲爱的{}}”链接到上面的“问候语”

邮件类型呼叫有“新邮件1”、“新邮件2”等

我的模型：

邮件设置

public function mail_setting_details(){
        return $this->hasMany('App\MailSettingDetail','MailSettingsTypeID','id' );
    }

邮件设置详细信息

protected $fillable = [
        'MailSettingsLineTypeID','MailSettingsTypeID','mail_line'

   public function mail_setting_line_type(){
        return $this->hasOne('App\MailSettingLineType','id','MailSettingsLineTypeID'    );
    }

    public function mail_setting(){
        return $this->hasOne('App\MailSetting','id','MailSettingsTypeID'    );
    }

MailSettingLineType

'mail_line_type'

public function mail_setting_details(){
    return $this->hasMany('App\MailSettingDetail','MailSettingsLineTypeID','id' );
}

在我的控制器中，我正在呼叫以获取特定的邮件模板：

$mail_setting = MailSetting::where('mail_type', 'New Email 2')->first();

我想获取Mail\u Settings\u Details.Mail\u line的值，其中Mail\u Settings\u line\u types.Mail\u line\u type为“主题”、“正文”等

如果我想得到“subject”，我想要的样本输出是“thisatestsubject”

'mail_line_type'

public function mail_setting_details(){
    return $this->hasMany('App\MailSettingDetail','MailSettingsLineTypeID','id' );
}

$mail_setting = MailSetting::where('mail_type', 'New Email 2')->first();