如何通过我的对象列表中的传递字符串值进行排序？我需要在我的List(Of)对象上进行分页和排序,分页没有问题,但我不知道是谁让Order By工作.
这是我目前正在做的事情,它的工作很棒：
Return returnReports.Skip(PageSize * (PageNumber-1)).Take(PageSize).ToList()
我如何让它工作？
Return returnReports.OrderBy(SortColumn).Skip(skip).Take(PageSize).ToList()
SortColumn是传递的字符串值
解决方法
VB
Module OrderByExtensions
<System.Runtime.CompilerServices.Extension()> _
Public Function OrderByPropertyName(Of T)(ByVal e As IEnumerable(Of T),ByVal propertyName As String) As IOrderedEnumerable(Of T)
Dim itemType = GetType(T)
Dim prop = itemType.GetProperty(propertyName)
If prop Is Nothing Then Throw New ArgumentException("Object does not have the specified property")
Dim propType = prop.PropertyType
Dim funcType = GetType(Func(Of,)).MakeGenericType(itemType,propType)
Dim parameter = Expression.Parameter(itemType,"item")
Dim exp = Expression.Lambda(funcType,Expression.MakeMemberAccess(parameter,prop),parameter)
Dim params = New Object() {e,exp.Compile()}
Return DirectCast(GetType(OrderByExtensions).GetMethod("InvokeOrderBy",Reflection.BindingFlags.Static Or Reflection.BindingFlags.NonPublic).MakeGenericMethod(itemType,propType).Invoke(Nothing,params),IOrderedEnumerable(Of T))
End Function
Private Function InvokeOrderBy(Of T,U)(ByVal e As IEnumerable(Of T),ByVal f As Func(Of T,U)) As IOrderedEnumerable(Of T)
Return Enumerable.OrderBy(e,f)
End Function
End Module
C#
public static class OrderByExtensions
{
public static IOrderedEnumerable<T> OrderByPropertyName<T>(this IEnumerable<T> e,string name)
{
var itemType = typeof(T);
var prop = itemType.GetProperty(name);
if (prop == null) throw new ArgumentException("Object does not have the specified property");
var propType = prop.PropertyType;
var funcType = typeof(Func<,>).MakeGenericType(itemType,propType);
var parameter = Expression.Parameter(itemType,"item");
var memberAccess = Expression.MakeMemberAccess(parameter,prop);
var expression = Expression.Lambda(funcType,memberAccess,parameter);
var x = typeof(OrderByExtensions).GetMethod("InvokeOrderBy",BindingFlags.Static | BindingFlags.NonPublic);
return (IOrderedEnumerable<T>)x.MakeGenericMethod(itemType,propType).Invoke(null,new object[] { e,expression.Compile() });
}
static IOrderedEnumerable<T> InvokeOrderBy<T,U>(IEnumerable<T> e,Func<T,U> f)
{
return e.OrderBy(f);
}
}
