orderby 嵌套 linq

发布于 2024-12-04 11:47:27 字数 428 浏览 0 评论 0原文

var query = from m in db.Members.Include("Companies.Projects.Experiences.ExperienceTags")
                    where m.MemberId == id                        
                    select m;

我也想从这个查询到 orderby the project.enddate。我该怎么做呢。 enddate 也可以为 null，然后我希望它是 orderby 时的今天日期。而且，公司可能并不总是有一个项目，那么它也应该在今天之前订购。

这是 ef 数据图的图像链接

原文

var query = from m in db.Members.Include("Companies.Projects.Experiences.ExperienceTags")
                    where m.MemberId == id                        
                    select m;

I would like to also from this query to orderby the project.enddate. How would I do that. Also enddate can be null which then I would like it to be today date when it orderby. And, a company might not always have a project either which then it should be orderby today date too.

here is a image of the ef data diagram a link

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海螺姑娘 2024-12-11 11:47:27

由于存在多种关系，您需要像这样执行 SelectMany：

var query = from m in db.Members.Include("Companies.Projects.Experiences.ExperienceTags")
            where m.MemberId == id
            orderby m.Companies.SelectMany(c => c.Projects).OrderByDescending(p => p.EndDate).FirstOrDefault() == null ? 
              DateTime.Today : 
              m.Companies.SelectMany(c => c.Projects).OrderByDescending(p => p.EndDate).FirstOrDefault()          
            select m;

Since there is a many relationship you need to do a SelectMany like so:

var query = from m in db.Members.Include("Companies.Projects.Experiences.ExperienceTags")
            where m.MemberId == id
            orderby m.Companies.SelectMany(c => c.Projects).OrderByDescending(p => p.EndDate).FirstOrDefault() == null ? 
              DateTime.Today : 
              m.Companies.SelectMany(c => c.Projects).OrderByDescending(p => p.EndDate).FirstOrDefault()          
            select m;

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