LINQ加入到一个一到多用。凡（）不工作？ [英] LINQ Include on a one-to-many with .Where() not working?

问题描述

我想查询用户，包括每个用户的兴趣，但只有在有兴趣满足一定的条件：

I'm trying to query Users including each user's Interests, but only where an Interest meets certain criteria:

  return db.Users.Include(u => u.Interests.Where(s => s.TenantId == tenantId))

不过，我得到一个错误：

But I get an error:

包含路径前pression必须指向一个导航属性
  的类型来定义。借鉴导航路径点
  属性和集合导航选择运营商
  属性。

The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operator for collection navigation properties.

我打外推。凡的想法，但一直没能得到它的工作。

I played with the idea of pushing the .Where outside, but haven't been able to get it working.

推荐答案

要只包括一些利益，你将无法使用包含方法，如它不支持这一点。你需要手动加入兴趣与用户：

To include only some of the interests you won't be able to use the Include method, as it doesn't support this. You'll need to manually join the Interests with the Users:

var query = from user in db.Users
    join interest in db.Interests.Where(s => s.TenantId == tenantId)
    on user.InterestId equals interest.Id //todo:  will need to be updated
    into interests;
    select new { user, interests};

这篇关于LINQ加入到一个一到多用。凡（）不工作？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！