如何在急切加载中获取关联表的行：Laravel 5.1答案

【问题标题】：How to get associated table's rows in eager loading: Laravel 5.1如何在急切加载中获取关联表的行：Laravel 5.1
【发布时间】：2017-08-11 19:21:21
【问题描述】：

我有三个数据库表。

CREATE TABLE `tblproject` (
  `ProjectID` int(11) NOT NULL,
  `ProjectStatusID` varchar(30) NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `tblprojectSkills` (
  `ProjectSkillID` int(11) NOT NULL,
  `ProjectID` int NOT NULL,
  `SkillID` int NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=latin1; 

CREATE TABLE `tblSkills` (
  `SkillID` int(11) NOT NULL,
  `Skill` varchar(100) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

在上面的表格中。 SkillID 与 tblSkills 和 tblprojectSkills 相关。 ProjectID 与 Project 和 projectSkills 表相关

我的项目模型如下。

class Project_Model extends Model
{
    protected $table = "tblproject";
    protected $primaryKey = "ProjectID";
    public $timestamps = false;

    public function ProjectSkills() {
        return $this->hasMany('\App\Models\ProjectSkill_Model', 'ProjectID');
    }        
}

class ProjectSkill_Model extends Model
{
    protected $table = "tblprojectskill";
    protected $primaryKey = "ProjectSkillID";
    public $timestamps = false;
}

class Skill_Model extends Model
{
    protected $table = "tblskill";
    protected $primaryKey = "SkillID";
    public $timestamps = false;
}

laravel 5.1 中的数据库查询如下。

\App\Models\Project\Project_Model
::with('ProjectSkills')
->where('ProjectID', '=', $ProjectID)->first();

问题

我可以获得技能 ID，但是，我如何从技能表中获取技能名称？

【问题讨论】：

您错误地定义了关系 - 查看多对多关系：laravel.com/docs/5.1/eloquent-relationships#many-to-many

标签： php laravel-5 laravel-5.1

【解决方案1】：

因此，您的验证将在每个事件中启动，focusout 等。因此，我添加了以下几行以仅在单击 button 后进行验证：

onfocusout: false,
onkeyup: false,
onclick: false,

其次，在您的CreateErrorMessage 中，我做了一些小改动，以便一次显示所有错误消息。 Message 是一个object 并且会有多个错误消息，因此它需要经过$.each。

最后，您在循环内检查ErrorMessages，理想情况下应该在循环外，这样检查只会发生一次。

以下是更新后的代码：

$(function() {
  $("form#loginForm").validate({
    onfocusout: false,
    onkeyup: false,
    onclick: false,
    rules: {
      EmailAddress: "required",
      Password: "required"
    },
    messages: {
      EmailAddress: {
        required: "Please enter email"
      },
      Password: {
        required: "Please enter Password"
      }
    },
    showErrors: function(errorMap, errorList) {
      RemoveErrorElements();
      CreateErrorMessage(errorList);
    }
  });
});

function CreateErrorMessage(errorList) {

  if ($(".panel-body").find("ul.ErrorMessages").length === 0) {
    $(".panel-body").prepend("<ul class='ErrorMessages'><ul>");
  }

  var ErrorMessages = $(".panel-body").find("ul.ErrorMessages");

  $.each(errorList, function(index, Message) {
    $(Message.element).parent().parent().addClass("has-error");
    $(Message).each(function(k, v) {
      ErrorMessages.append("<li>" + v.message + "</li>");
    })

  });
}

function RemoveErrorElements() {
  $(".panel-body").find("ul.ErrorMessages").remove();
}

<!DOCTYPE html>
<html>

<head>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.min.css">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.17.0/jquery.validate.js"></script>
  <script src="script.js"></script>
</head>

<body>
  <div class="container">
    <div class="row">
      <div class="col-md-8 col-md-offset-2">
        <div class="panel panel-default">
          <div class="panel-heading">Login</div>
          <div class="panel-body">
            <form id="loginForm" class="form-horizontal form-label-left" novalidate="novalidate">
              <input name="_token" type="hidden" value="qZuutEkhKvETtiuA3stgpOyOiH7FrKXUPz7C7bxe">
              <div class="form-group has-error">
                <label for="EmailAddress" class="col-md-4 control-label">UserName / E-Mail Address</label>
                <div class="col-md-6">
                  <input name="EmailAddress" type="text" class="form-control">
                </div>
              </div>
              <div class="form-group has-error">
                <label for="Password" class="col-md-4 control-label">Password</label>
                <div class="col-md-6">
                  <input name="Password" type="password" value="" class="form-control">
                </div>
              </div>
              <div class="form-group">
                <div class="col-md-8 col-md-offset-4">
                  <button type="submit" class="btn btn-primary">
                                            Login
                                        </button>
                </div>
              </div>
            </form>
          </div>
        </div>
      </div>
    </div>
  </div>
</body>

</html>

【讨论】：

【解决方案2】：

class Project_Model extends Model
{
    protected $table = "tblproject";
    protected $primaryKey = "ProjectID";
    public $timestamps = false;

    public function ProjectSkills() {
        return $this->hasMany('\App\Models\ProjectSkill_Model', 'ProjectID');
    }        
}

class ProjectSkill_Model extends Model
{
    protected $table = "tblprojectskill";
    protected $primaryKey = "ProjectSkillID";
    public $timestamps = false;


    public function Skills() {
        return $this->hasOne('\App\Models\Skill_Model', 'ProjectSkillID');
    }
}

class Skill_Model extends Model
{
    protected $table = "tblskill";
    protected $primaryKey = "SkillID";
    public $timestamps = false;
}

获取技能名称

$project_info = \App\Models\Project\Project_Model->where('ProjectID', '=', $ProjectID)->first();

foreach($project_info->ProjectSkills as $ProjectSkills) {
     dd($ProjectSkills->skill_name);
}

【讨论】：

【解决方案3】：

正如您粘贴的那样，您不需要中间表。并添加外键ProjectID 引用tblproject 表。

像这样改变Project_Model中的关系方法：

public function Skills() {
    return $this->hasMany('\App\Models\Skill_Model', 'ProjectID');
}

并执行查询语句：

$project = \App\Models\Project\Project_Model::where('ProjectID', $ProjectID)->with(['Skills' => function ($query) {
    $query->addSelect(['SkillID', 'Skill', 'ProjectID']);
}])->get();

【讨论】：