如何在一个模型中合并两个不同的模型并在一个视图中显示输出？

Question

这是我的模特

    {
        public int Id { get; set; }
        public int? MainSurveyId { get; set; }
        public string Question { get; set; }
        public DateTime? DateCreated { get; set; }
        public string CreatedBy { get; set; }
        public string Status { get; set; }
        public IList<xxAnswer> answers { get; set; }
    }

这是我的控制器，请注意我将var question和var answer分开了

 [HttpPost]
        public IActionResult CompareCompetitors(string[] comps, int Surveyid)
        {
           var model = new CompareCompetitorAnswers();
           foreach( var item in comps){
               model.competitorNames.Add( new xxCompetitor() { CompetitorName = item} );
           }

            var questions = _context.SurveyQuestions.ToList().Where(x => x.MainSurveyId == Surveyid);
            foreach (var q in questions){
                model.questions.Add(new xxQuestion { Question = q.Question});
            }

             var answers = _context.SurveyCompetitorAnswer.ToList().Where(x => x.MainSurveyId == Surveyid);
            foreach (var a in answers){
                model.answers.Add(new xxAnswer { Answer = a.Answer});
            }


            return View(model);
            //return string.Join(",", comps); // check if it works with this. ph wait. i think correct. sorry. i will try now.
        }

这是我的观点，但它在@foreach (var a in q.answers)中显示错误。

 <tbody>
         @foreach (var q in Model.questions)
            {
                <tr>
                    <td scope="row">
                        @q.Question
                    </td>
                    @foreach (var a in q.answers)
                    {
                        <td scope="row">
                            @a.Answer
                        </td>    
                    }


                </tr>
            }
        </tbody>

我希望将答案张贴在结果旁边。它们位于不同的数据库表中。但它在@foreach (var a in q.answers)输出错误。

Answer 1

我终于弄明白了：

<tbody>      
    @foreach (var q in Model.questions)
    {
      <tr>
      <td scope="row">
        @q.Question
      </td>
      @foreach (var a in Model.answers.Where(x => x.SurveyQuestionId == q.Id))
      {
         <td scope="row">
           @a.Answer
         </td>    
      }
      </tr>
    }
</tbody>

我没用过

public IList<xxAnswer> answers { get; set; }

我刚用过：

@foreach (var a in Model.answers.Where(x => x.SurveyQuestionId == q.Id))

Answer 2

我有点迟了，但我希望这会帮助你优化你的模型方法。

假设这是您的简化模型：

public class AnswerModel
{
   // Omitted for simplicity
}

public class QuestionModel
{
    public List<AnswerModel> Answers { get; set; } = new List<AnswerModel>();
}

你不应该在.Where（）之前执行.ToList（）因为你实际上实现了整个实体（也就是表）。如果您使用联接来执行查询，或者如果您愿意，可以使用NavigationProperty（如果有的话）来跟踪与您的问题相关的答案集合。

LINQ basics

但是我使用你的方法有两个分开的查询：

var model = new List<QuestionModel>();
var questions = _context.SurveyQuestions.Where(x => x.MainSurveyId == Surveyid).ToList();
var answers = _context.SurveyCompetitorAnswer.Where(x => x.MainSurveyId == Surveyid).ToList();
foreach (var q in questions){
    var qModel = new QuestionModel();
    qModel.Answers.AddRange(answers.Where(x => x.SurveyQuestionId == q.Id).ToList());
    model.Add(qModel);
}

并且使用更简单和聚合的模型：

<tbody>
    @foreach (var q in Model)
    {
        <tr>
            <td scope="row">
                @q.Question
            </td>
            @foreach (var a in q.Answers)
            {
                <td scope="row">
                    @a.Answer
                </td>    
            }
        </tr>
    }
</tbody>

如果您要共享您的实体，我们可以优化查询！

快乐的编码！