join子句中表达式之一的类型在Entity Framework中不正确.左连接常数 [英] The type of one of the expressions in the join clause is incorrect in Entity Framework. Constant in left join

问题描述

我正在尝试在EF查询中进行左连接.我收到以下错误:

I'm trying to do a left join in an EF query. I'm getting the following error:

错误CS1941 join子句中的表达式之一的类型为 不正确.调用"GroupJoin"时类型推断失败

Error CS1941 The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'GroupJoin'

这是C#代码:

var foo = from m in db.ClientMasters
                      join a in db.Orders on new { m.Id, Status = "N" } equals new { a.ClientID, a.Status } into a_join
                      from a in a_join.DefaultIfEmpty()
                      select new { m.ClientID, a.ID };

推荐答案

我是个白痴.联接中的列名必须匹配.这是更正的代码.

I'm an idiot. The column names have to match in the join. here is the corrected code.

var foo = from m in db.ClientMasters
                      join a in db.Orders on new { ClientID = m.Id, Status = "N" } equals new { a.ClientID, a.Status } into a_join
                      from a in a_join.DefaultIfEmpty()
                      select new { ClientID = m.Id, OrderId = a.Id };

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