LINQ 动态分组 [英] LINQ Grouping dynamically

问题描述

我有一个记录类列表，因此用户可以选择按属性名称对行进行动态分组.例如MenuText、RoleName 或ActionName.然后我必须执行分组，所以我需要一个通用方法来通过传递列名来处理分组.

I have a class list of records, so user can select to group rows dynamically by property name. For example MenuText, RoleName or ActionName. Then I have to execute grouping so I need a generic method to handle grouping by passing column name.

示例:

public class Menu
{
  public string MenuText {get;set;}
  public string RoleName {get;set;}
  public string ActionName {get;set;}
}

public class Menus 
{
 var list = new List<Menu>();
 list.Add( new Menu {MenuText="abc",RoleName ="Admin", ActionName="xyz"};
 list.Add( new Menu {MenuText="abc",RoleName ="Admin", ActionName="xyz"};
 list.Add( new Menu {MenuText="abc1",RoleName ="Admin1", ActionName="xyz1"};
 list.Add( new Menu {MenuText="abc1",RoleName ="Admin1", ActionName="xyz1"};

  /// columnName :- Name of the Menu class ( MenuText  or RoleName  or ActionName)

  public IEnumerable<IGrouping<string,IEnumerable<Menu>>> GroupMenu(string columnName)
  {
          // Here I want to get group the list of menu by the columnName 
  }
}

推荐答案

如果您不使用数据库，您可以使用反射:

If you're not working with a database you can use Reflection:

private static object GetPropertyValue(object obj, string propertyName)
{
    return obj.GetType().GetProperty(propertyName).GetValue(obj, null);
}

用作:

var grouped = enumeration.GroupBy(x => GetPropertyValue(x, columnName));

这是一个非常原始的解决方案，更好的方法应该是使用 动态 LINQ:

This is a pretty raw solution, a better way should be to use Dynamic LINQ:

var grouped = enumeration.GroupBy(columnName, selector);

EDIT 动态 LINQ 可能需要一些解释.它不是一项技术、一个库或一个全新的框架.它只是让您编写此类查询的几个 (2000 LOC) 助手方法的方便名称.只需下载他们的源代码(如果您没有安装 VS 示例)并在你的代码.

EDIT Dynamic LINQ maybe needs some explanations. It's not a technology, a library or a brand new framework. It's just a convenient name for a couple (2000 LOC) of helpers methods that let you write such queries. Just download their source (if you don't have VS samples installed) and use them in your code.

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