c# - 对在 ASP.NET 中进一步具有对象的对象列表进行排序

Question

我有一个对象列表，其中还有对象对于例如。

Class Customer{
    string name;
    Address addr;
}

Class Address
{
    string city;
    string state;
}

现在我有一个绑定(bind)到 gridview 的客户对象列表。

| Name | city | State |

我想根据城市和州对 gridview 列进行排序。我将如何做。

我试过

var param = Expression.Parameter(typeof(Customer), e.SortExpression);
var sortExpression = Expression.Lambda<Func<Customer, object>>(
    Expression.Convert(Expression.Property(param, e.SortExpression),typeof(object)), param);

但是当排序表达式是city时，它不排序。

Answer 1

这是我正在运行的示例:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;

public class Program
{
    public static void Main()
    {
        var list = new List<Customer>();

        list.Add(new Customer()
        {
            FirstName = "ztest",
            LastName = "ztest1",
            Address = new Address()
            {
                City = "Kiev"
            }
        });
        list.Add(new Customer()
        {
            FirstName = "test",
            LastName = "test1",
            Address = new Address()
            {
                City = "New York"
            }
        });


        string sortExpressionField = "Address.City";


        var props = sortExpressionField.Split('.');
        var inParam = Expression.Parameter(typeof(Customer));
        var param = props.Aggregate<string, Expression>(inParam, Expression.Property);
        var sortExpression = Expression.Lambda<Func<Customer, object>>(param, inParam);

        var sorted = list.AsQueryable<Customer>().OrderBy(sortExpression);
        foreach (var item in sorted)
        {
            Console.WriteLine("{0} {1}", item.FirstName, item.LastName);
        }
    }

}

public class Customer
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Address Address { get; set; }
}

public class Address
{
    public string City { get; set; }
}

这是验证它是否有效的链接 - http://dotnetfiddle.net/iQSTBR

更新1

对于复杂的情况，您需要解析属性，并导航到最后一个属性。我更新了代码，这里是使用子属性的示例 - http://dotnetfiddle.net/alTWPK

更新 2

 var selectedNew = selected
       .AsQueryable<Customer>()
       .OrderBy(sortExpression)
       .ToList();
 gdvEmployees.DataSource = selectedNew; 
 gdvEmployees.DataBind();