Question

我在ASP.NET Core WebAPI项目中使用Entity Framework Core 2.0.2。我有以下实体：

NotificationReported.cs：

public class NotificationReported
{
    public NotificationReported();

    public int Id { get; set; }
    public Guid Guid { get; set; }
    public Guid PlantId { get; set; }

    public ICollection<Photo> Photo { get; set; }
    public ICollection<Response> Response { get; set; }
}

Photo.cs：

public class Photo
{
    public Photo();

    public int Id { get; set; }
    public string Name { get; set; }
    public string Status { get; set; }

    public int NotificationReportedId { get; set; }
    public NotificationReported NotificationReported { get; set; }
}

Response.cs：

public class Response
{
    public Response();

    public int Id { get; set; }
    public int QuestionId { get; set; }
    public int NotificationReportedId { get; set; }
    public string Value { get; set; }

    public NotificationReported NotificationReported { get; set; }
    public Question Question { get; set; }
}

我想做LEFT JOIN，我想要包括那些孩子。这是我写的：

        var tableNotifReported = _myNotifContext.NotificationReported
            .Include(nr => nr.Response)
                .ThenInclude(res => res.Question)
                    .ThenInclude(question => question.QuestionTypeRef)
            .Include(nr => nr.Photo);

这是LINQ：

        var query = (from notifReported in tableNotifReported 
                     join response in _myNotifContext.Response
                        on notifReported.Id equals response.NotificationReportedId into joinResponse
                     from res in joinResponse.DefaultIfEmpty()

                     join question in _myNotifContext.Question
                        on res.QuestionId equals question.Id into joinQuestion
                     from ques in joinQuestion.DefaultIfEmpty()

                     join notifTemplate in _myNotifContext.NotificationTemplate
                        on notifReported.TemplateId equals notifTemplate.Guid
                     select new NotificationsReportedQuery
                     {
                         NotificationReported = notifReported,
                         Response = res,
                         Question = ques,
                         NotificationTemplate = notifTemplate
                     })
                     .Where(predicate)
                     .Select(nrq => nrq.NotificationReported)
                     .Distinct();

在调用ToListAsync（）之后，我的对象列表没有他的孩子=＆gt;响应（计数= 0）和照片（计数= 0）

但是当我使用通常的JOIN（内部加入）时，我的孩子就在这里。缺少什么？

INNER JOIN的代码正在工作，但是我需要LEFT JOIN，因为在这种情况下NotificationReported可能没有用户回答的响应，因此INNER JOIN不会报告这种情况通知：

        var query = (from notifReported in tableNotifReported
                     join response in _myNotifContext.Response
                        on notifReported.Id equals response.NotificationReportedId

                     join question in _myNotifContext.Question
                        on response.QuestionId equals question.Id

                     join notifTemplate in _myNotifContext.NotificationTemplate
                        on notifReported.TemplateId equals notifTemplate.Guid
                     select new NotificationsReportedQuery
                     {
                         NotificationReported = notifReported,
                         Response = response,
                         Question = question,
                         NotificationTemplate = notifTemplate
                     })
                     .Where(predicate)
                     .Select(nrq => nrq.NotificationReported)
                     .Distinct();

编辑：这就是我对LINQ LEFT JOIN所做的事情（它不包括它的孩子）：

这就是我对经典INNER JOIN的看法（对于同样的通知，包括孩子们）：

LINQ - 左连接包括然后包括儿童不工作

0 个答案: