Lambda表达式返回错误

本文介绍了Lambda表达式返回错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

这是我的代码:

SomeFunction(m => { ViewData["AllEmployees"].Where(c => c.LeaderID == m.UserID); })

，它返回此错误:

并非所有代码路径都在类型为System.Func<IEnumerable>

Not all code paths return a value in lambda expression of type System.Func<IEnumerable>

推荐答案

假设您要返回该.Where()查询的结果，则需要删除括号和分号:

Assuming you're trying to return the result of that .Where() query, you need to drop those braces and that semicolon:

SomeFunction(m => ViewData["AllEmployees"].Where(c => c.LeaderID == m.UserID))

如果将它们放在此处，ViewData[...].Where()将被视为语句而不是表达式，因此您最终得到的lambda在预期的情况下不会返回，从而导致错误.

If you put them there, ViewData[...].Where() will be treated as a statement and not an expression, so you end up with a lambda that doesn't return when it's supposed to, causing the error.

或者，如果您坚持将它们放在此处，则需要一个return关键字，以便该语句实际返回:

Or if you insist on putting them there, you need a return keyword so the statement actually returns:

SomeFunction(m => { return ViewData["AllEmployees"].Where(c => c.LeaderID == m.UserID); })