具有相同键的项已存在

Question

对LINQ 来说相当新手，无法理解为什么我会收到此错误：

已添加具有相同键的项目。

我在想，因为我使用了 3 次选择 lambda 表达式？否则，从代码中，我看不到如何多次分配任何属性。 有没有更好的方法来写这个和解释？谢谢。

视图模型：

public class AwardWinnersViewModel
{
public int WinnerId { get; set; }
public string AwardName { get; set; }
public DateTime StartDate { get; set; }
public string Contact { get; set; }
public int Type { get; set; }
public int JurisdictionRef { get; set; }
public int WorkareaRef { get; set; }
public string Jurisdiction { get; set; }
public string Workarea { get; set; }
public string LogoUrl { get; set; }
}
public class AwardWinnersWrapperVM
{
public IEnumerable<KeyValuePair<short, string>> JurisdictionFilter { get; set; }
public IEnumerable<KeyValuePair<int, string>> WorkareaFilter { get; set; }
public IEnumerable<AwardWinnersViewModel> AwardWinners { get; set; }
public int Page { get; set; }
public int WinnersPerPage { get; set; }
public bool HasPrevious { get; set; }
public bool HasNext { get; set; }
public int TotalWinners { get; set; } 
public int? ResultsOutOf { get => (this.WinnersPerPage * (this.Page + 1)) < this.TotalWinners ? (this.WinnersPerPage * (this.Page + 1)) : this.TotalWinners; }
public int NumberOfPips { get => this.TotalWinners / WinnersPerPage; }
public int? SelectedJurisdiction { get; set; }
public int? SelectedWorkarea { get; set; }
}

控制器：

[HttpGet]
public async Task<ActionResult> Index(int? page, int? additionalJurisdictionSearch, int? additionalWorkareaSearch)
{
var awardWinners = await awardWinnersService.GetAwardWinnersAsync();
var jurisdictions = contentMetadataService.GetJurisdictions();
var workareas = contentMetadataService.GetWorkareas();
int pageNumber = page ?? 0;
var viewModel = new AwardWinnersWrapperVM
{
TotalWinners = awardWinners.Count(),
WinnersPerPage = winnersPerPage,
Page = pageNumber,
HasPrevious = pageNumber > 0,
HasNext = awardWinners.Count() > (winnersPerPage * (pageNumber + 1)),
AwardWinners = awardWinners.Select(x => new AwardWinnersViewModel
{
Type = x.Type,
Contact = (x.Type == 1)
? x.WinnerId != 0 ? contributorService.GetContributor(x.WinnerId, true)?.DisplayName : string.Empty
: x.WinnerId != 0 ? authorService.GetByRef(x.WinnerId, true)?.AuthorName : string.Empty,
StartDate = x.StartDate,
AwardName = x.AwardName,
Jurisdiction = x.Jurisdiction,
Workarea = x.Workarea,
LogoUrl = (x.Type == 1)
? contributorService.GetContributor(x.WinnerId, true)?.LogoImageUrlCDN
: authorService.GetByRef(x.WinnerId, true)?.PhotoUrl,
}),
JurisdictionFilter = awardWinners.Select(x => new { id = x.JurisdictionRef, display = (jurisdictions.TryGetValue((short)x.JurisdictionRef, out var jurisdiction) ? jurisdiction.JurisdictionName : string.Empty) }).ToDictionary(key => (short)key.id, val => val.display),
WorkareaFilter = awardWinners.Select(x => new { id = x.WorkareaRef, display = (workareas.TryGetValue(x.WorkareaRef, out var workarea) ? workarea.WorkareaName : string.Empty) }).ToDictionary(key => key.id, val => val.display)
.Skip(winnersPerPage * (pageNumber - 1))
.Take(winnersPerPage)
};
return View(viewModel);
}

Answer 1

如果您的任何awardWinners共享jurisdictionRef或workareaRef则ToDictionary()会调用JurisdictionFilter，并且WorkareaFilter将因该异常而失败。

我认为您只想为您的过滤器盒抓取不同的司法管辖区/工作区(这可能在ToDictionary之前使用.Distinct()来实现(。