GroupJoin with list返回多个结果，而不是按结果附加列表

Question

我使用GroupJoin查询项目列表（父项目）和GroupJoin到项目列表（第一个子项目）到第二个列表（第二个子项目），其中fk到第一个子项目。为每个项目获取一个列表（父项目）我每个项目获得一个项目（所以我只想获得一个单项结果，每个项目列表（“父”）项目多次与一个项目（“第一个子项目”） “）结果。

我希望代码能更好地解释。

实体模型：

public class QuettaReq
{
    public QuettaReq()
    {
    }

    [Key] public int             Id   { get; set; }
    public       ApplicationUser User { get; set; }

    public Category Category { get; set; }

    public int CatId { get; set; }
    //Parameters 

    public virtual List<QuettaOffer>   QuettaOffer    { get; set; }
    public virtual List<QuoteQuestion> QuoteQuestions { get; set; }
}

public class QuoteQuestion
{
    [Key] public int QuoteQuestionId { get; set; }

    public int       QuoteId   { get; set; }
    public QuettaReq QuettaReq { get; set; }

    public string         Question { get; set; }
    public IList<Answers> Answers  { get; set; }
}

查看型号：

public class ReqestWithQA
{
    [Key] public int Id { get; set; }

    //public ApplicationUser User { get; set; }
    public string SiteUserId { get; set; }

    //properties
    public virtual IList<QAViewModel> QAViewModel { get; set; }
    public         int                QuettaReqId { get; set; }
}

public class QAViewModel
{
    public int    QuoteQuestionId { get; set; }
    public int    QuoteId         { get; set; }
    public string Question        { get; set; }

    public IList<Answers> Answers { get; set; }
}

查询：

IQueryable<ReqestWithQA> viewModel = _context.Quetta
        .Include(q => q.Category)
        .Where(d => d.OfferDate > DateTime.Now && d.CatId == suplayerCat)
        .Where(rq => !postOn.Contains(rq.Id))
        .GroupJoin(
            _context.quoteQuestions.Include(t => t.Answers),
            quetta => quetta.Id,
            qestion => qestion.QuoteId,
            (quetta, joinQestionQuetta) => new ReqestWithQA
            {
                ReqText         = quetta.ReqText,
                Qentity         = quetta.Qentity,
                CatId           = quetta.CatId,
                CatName         = quetta.Category.CatName,
                District        = quetta.District,
                ApplicationDate = quetta.ApplicationDate,
                DeliveryDate    = quetta.DeliveryDate,
                OfferDate       = quetta.OfferDate,
                TecnicalDetails = quetta.TecnicalDetails,
                Bedget          = quetta.Bedget,
                Id              = quetta.Id,
                QAViewModel = new[] {
                    joinQestionQuetta
                        .Select(q => new QAViewModel
                        {
                            Question = q.Question, //there are 6 question
                            Answers  = q.Answers,
                            QuoteId  = q.QuoteId

                        })
                        .FirstOrDefault()
                }
            });

return View(viewModel.Distinct().ToList()); //viewModel results are 6 Should be 1 with 6 Q

我认为问题是阵列，但我不知道该用什么代替：

QAViewModel = new[] {
    joinQestionQuetta
        .Select(q => new QAViewModel