“具有语句正文的lambda表达式不能被转换为表达式树” [英] "A lambda expression with a statement body cannot be converted to an expression tree"

问题描述

在使用 EntityFramework 时，我收到错误尝试使用语句正文的lambda表达式无法转换为表达式树编译以下代码：

In using the EntityFramework, I get the error "A lambda expression with a statement body cannot be converted to an expression tree" when trying to compile the following code:

Obj[] myArray = objects.Select(o =>
{
    var someLocalVar = o.someVar;

    return new Obj() { 
    Var1 = someLocalVar,
    Var2 = o.var2 };
}).ToArray();

我不知道错误是什么意思，最重要的是如何解决它。任何帮助？

I don't know what the error means and most of all how to fix it. Any help?

推荐答案

是对象一个Linq-To-SQL数据库背景？在这种情况下，您只能使用=>操作符右侧的简单表达式。原因是这些表达式未被执行，而是转换为SQL以对数据库执行。
尝试这个

Is objects a Linq-To-SQL database context? In which case, you can only use simple expressions to the right of the => operator. The reason is, these expressions are not executed, but are converted to SQL to be executed against the database. Try this

Arr[] myArray = objects.Select(o => new Obj() { 
    Var1 = o.someVar,
    Var2 = o.var2 
}).ToArray();

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