LINQ Let运算符具有lambda语法 [英] LINQ Let operator with lambda syntax

问题描述

我知道linq查询语法中有let运算符.存储子表达式的结果以在后续子句中使用它很有用.

I know that there is let operator in linq query syntax. It is useful to store the result of a sub-expression in order to use it in subsequent clauses.

• https://docs.microsoft .com/en-us/dotnet/csharp/language-reference/keywords/let-clause

但是我更喜欢使用linq lambda语法.当我处理大量联接时，我得到对象链(代表联接的每个级别，即:`

But I prefer work with linq lambda syntax. When I work with a lot of joins i get chain of objects (which represent each level of joins ie: `

s.secondJoin.firstJoin.dd.DataType`

我想在变量中设置一些子结果，并将其用于以下更方便的工作:

I would like to set some sub result in variable and use it for more convinient work in the following ie:

let joinResult = s.secondJoin.firstJoin及之后的
joinResult.dd.DataType

let joinResult = s.secondJoin.firstJoin and after
joinResult.dd.DataType

问:是否可以使用linq lambda语法?

Q: Is it possible in linq lambda syntax?

推荐答案

在lambda语法中，与let等效的是Select，用于创建匿名类型，例如:

Equivalent to let in lambda syntax is Select to create an anonymous type, for example:

items.Select(s => new
{
    s = s,
    joinResult = s.secondJoin.firstJoin
})

此后，您可以像使用let一样在查询语法中同时使用s和joinResult.

After this you can use both s and joinResult as you could with let in query syntax.

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