C# 如何将 IQueryable<T> 转换为 List<T>?

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时间:2020-08-06 14:16:24  来源:igfitidea点击:

How to convert an IQueryable<T> to a List<T>?

c#linqiqueryable

提问by Prabu

Just learning LINQ and i've come to a newbie roadblock in my test project. Can you explain what i'm doing wrong?

刚刚学习 LINQ,我在我的测试项目中遇到了新手障碍。你能解释一下我做错了什么吗?

public List<ToDoListInfo> retrieveLists(int UserID)
{
//Integrate userid specification later - need to add listUser table first
IQueryable<ToDoListInfo> lists = 
    from l in db.ToDoLists
    select new ToDoListInfo { 
        ListID = l.ListID, 
        ListName = l.ListName, 
        Order = l.Order, 
        Completed = l.Completed 
    };

    return lists.ToList<ToDoListInfo>;
}     

I'm getting an error saying the following:

我收到一条错误消息,内容如下:

Cannont convert method group 'ToList' to non-delegate type 'System.Collections.Generic.List' Do you intend to invoke the method?

无法将方法组“ToList”转换为非委托类型“System.Collections.Generic.List”您是否打算调用该方法?

采纳答案by Thomas Danecker

You just need parantheses:

你只需要括号:

lists.ToList<ToDoListInfo>();

lists.ToList<ToDoListInfo>();

Also, you do not have to declare the type parameter, i.e. you could use the following and let the type-system infer the type parameter:

此外,您不必声明类型参数,即您可以使用以下内容并让类型系统推断类型参数:

lists.ToList();

lists.ToList();

回答by Nathan W

You are just missing the closing brackets on ToList, should be:

您只是缺少 ToList 上的右括号,应该是:

 ToList();

or

或者

ToList<ToDoListInfo>();