C# MVC：Func如何获得动态类型？

发布于 2024-09-08 19:54:52 字数 752 浏览 5 评论 0原文

嘿，我正在尝试根据用户单击的内容对列的自定义数据网格进行排序。变量“sort”被传递到控制器，但它只是一个字符串，说明要对哪一列进行排序。

我需要获取要在 LambdaExpression 中使用的该列的类型...这是代码，

ParameterExpression param = Expression.Parameter(typeof(Table1), "x");
MemberExpression memberExp = Expression.Property(param, sort);      
var lambdaExp = Expression.Lambda<Func<Table1, int>>(memberExp, new ParameterExpression[] { param });

if (bool.Parse(Session["sort"].ToString()))
    sortedKeys = keys.OrderBy(lambdaExp).Skip((currentPage - 1) * _pageSize).Take(_pageSize);
else
    sortedKeys = keys.OrderByDescending(lambdaExp).Skip((currentPage - 1) * _pageSize).Take(_pageSize);

正如您在第 3 行中看到的那样，我传递了委托 Func 用于具有 int 类型的列，但这将根据单击的列动态更改。

我该如何解决这个问题？

谢谢！

原文

Hey, I'm trying to sort a custom data grid of columns based on what the user clicked. The variable "sort" is being passed to the controller but is just a string saying what column is to be sorted.

I need to get the Type of that column to be used in a LambdaExpression... heres the code

ParameterExpression param = Expression.Parameter(typeof(Table1), "x");
MemberExpression memberExp = Expression.Property(param, sort);      
var lambdaExp = Expression.Lambda<Func<Table1, int>>(memberExp, new ParameterExpression[] { param });

if (bool.Parse(Session["sort"].ToString()))
    sortedKeys = keys.OrderBy(lambdaExp).Skip((currentPage - 1) * _pageSize).Take(_pageSize);
else
    sortedKeys = keys.OrderByDescending(lambdaExp).Skip((currentPage - 1) * _pageSize).Take(_pageSize);

As you can see on line #3 where I pass the delegate Func works from for a column that has a Type of int, but that will change dynamically depending on what column was clicked.

How do I solve this?

Thanks!

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

美煞众生 2024-09-15 19:54:52

我假设您有方便的列类型，它将是 System.Type。我们称之为“columnType”。所以你想要做的是使用非泛型 Lambda 方法：

Type funcType = typeof(Func<,>).MakeGenericType(typeof(Table1), columnType);
Expression.Lambda(funcType, memberExp, new ParameterExpression[] { param });

I assume you have the column type handy, which will be a System.Type. Let's call it "columnType". So what you'd want to do is use the non-generic Lambda method:

Type funcType = typeof(Func<,>).MakeGenericType(typeof(Table1), columnType);
Expression.Lambda(funcType, memberExp, new ParameterExpression[] { param });

回复收藏 0 原文

~没有更多了~