ASP.Net 4.5模型绑定按导航属性排序
本文关键字:导航 属性 排序 绑定 模型 Net ASP | 更新日期: 2023-09-27 18:13:48
全部,
我有一个网格视图,它包含以下列。分页很好,但排序不好。每次我点击"类别"列按类别排序时,我都会收到以下错误:
没有为类型"ESA.Data.Models.Entity.Project"定义实例属性"Category.CategoryName">
此错误语句不正确,因为gridview能够正确显示列。
以下是的选择方法
public IQueryable<Project> getProjects()
{
ApplicationServices objServices = new ApplicationServices();
IQueryable<Project> lstProject;
lstProject = objServices.getProjects();
return lstProject;
}
有什么建议吗?
<asp:GridView ID="grdProject" runat="server" ShowHeader="true"
AutoGenerateColumns="false" CellPadding="2" CellSpacing="2"
ItemType="ESA.Data.Models.Entity.Project"
SelectMethod="getProjects"
DataKeyNames="ProjectID"
AllowSorting="true"
AllowPaging="true"
PageSize="5">
<Columns>
<asp:BoundField DataField="ProjectID" HeaderText="ID " ItemStyle-Width="10" />
<asp:BoundField DataField="Category.CategoryName" HeaderText="Category" SortExpression="Category.CategoryName" />
<asp:BoundField DataField="ProjectName" HeaderText="Project Name" ItemStyle-Width="300" />
<asp:BoundField DataField="Status.StatusName" HeaderText="Status" SortExpression="Status.StatusName" />
<asp:BoundField DataField="AddedByUser.UserName" HeaderText="Added By" ItemStyle-Width="120" />
<asp:BoundField DataField="AddedDate" HeaderText="Added Date" ItemStyle-Width="90" DataFormatString="{0:d}" />
</Columns>
</asp:GridView>
我在Listview控件中遇到了类似的问题。我就这样解决了。
首先,我在IEnumerable<T>
在Listview的"OnSorting"事件中,我添加了以下代码。
protected void lv_Sorting(object sender, ListViewSortEventArgs e)
{
e.Cancel = true;
ViewState["OrderBy"] = e.SortExpression;
lvList.DataBind();
}
我添加了一种相当标准的方式来捕获这个的分拣方向列表
public SortDirection sortDirection
{
get
{
if (ViewState["sortdirection"] == null)
{
ViewState["sortdirection"] = SortDirection.Ascending;
return SortDirection.Ascending;
}
else if ((SortDirection)ViewState["sortdirection"] == SortDirection.Ascending)
{
ViewState["sortdirection"] = SortDirection.Descending;
return SortDirection.Descending;
}
else
{
ViewState["sortdirection"] = SortDirection.Ascending;
return SortDirection.Ascending;
}
}
set
{
ViewState["sortdirection"] = value;
}
}
在我的Listview中,Selectmethod看起来像这样(使用Marc的扩展方法(
public IQueryable<SomeObject> GetObjects([ViewState("OrderBy")]String OrderBy = null)
{
var list = GETSOMEOBJECTS();
if (OrderBy != null)
{
switch (sortDirection)
{
case SortDirection.Ascending:
list = list.OrderByDescending(OrderBy);
break;
case SortDirection.Descending:
list = list.OrderBy(OrderBy);
break;
default:
list = list.OrderByDescending(OrderBy);
break;
}
}
return list;
}
我还没有在GridView中尝试过,但我很确定它也能正常工作。
编辑下面是一个linq扩展类的例子,它应该可以在中工作
public static class LinqExtensions
{
public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property)
{
return ApplyOrder<T>(source, property, "OrderBy");
}
public static IOrderedQueryable<T> OrderByDescending<T>(this IQueryable<T> source, string property)
{
return ApplyOrder<T>(source, property, "OrderByDescending");
}
public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property)
{
return ApplyOrder<T>(source, property, "ThenBy");
}
public static IOrderedQueryable<T> ThenByDescending<T>(this IOrderedQueryable<T> source, string property)
{
return ApplyOrder<T>(source, property, "ThenByDescending");
}
static IOrderedQueryable<T> ApplyOrder<T>(IQueryable<T> source, string property, string methodName)
{
string[] props = property.Split('.');
Type type = typeof(T);
ParameterExpression arg = Expression.Parameter(type, "x");
Expression expr = arg;
foreach (string prop in props)
{
// use reflection (not ComponentModel) to mirror LINQ
PropertyInfo pi = type.GetProperty(prop);
expr = Expression.Property(expr, pi);
type = pi.PropertyType;
}
Type delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type);
LambdaExpression lambda = Expression.Lambda(delegateType, expr, arg);
object result = typeof(Queryable).GetMethods().Single(
method => method.Name == methodName
&& method.IsGenericMethodDefinition
&& method.GetGenericArguments().Length == 2
&& method.GetParameters().Length == 2)
.MakeGenericMethod(typeof(T), type)
.Invoke(null, new object[] { source, lambda });
return (IOrderedQueryable<T>)result;
}
}
只需在页面上添加一个使用"whatevernamespaceyouused",你就可以开始了。
将名为sortByExpression
的字符串参数添加到getProjects()
方法中。
如果gridView在你的方法签名中找到了这个参数,它不会试图"自动排序"你的结果,它会让你完成这项工作。
要自己完成这项工作,可以使用DynamicLinq(可以添加nuget包,也可以使用Drauka发布的LinqExtensions
类(。
所以你的方法看起来是这样的:
// using System.Linq.Dynamic;
public IQueryable<Project> getProjects(string sortByExpression)
{
ApplicationServices objServices = new ApplicationServices();
IQueryable<Project> lstProject = objServices.getProjects();
if (!String.IsNullOrEmpty(sortByExpression))
lstProject = lstProject.OrderBy(sortByExpression);
return lstProject;
}
这样就不会绕过gridView排序样式。
源:反编译的框架代码,特别是System.Web.UI.WebControls.ModelDataSourceView.IsAutoSortingRequired(...)
Drauka您的解决方案对我有效,但如果我已经引用了System.Linq.Dynamic ,我会在这行代码中出错
给我语法错误的两行是
lstProject=lstProject.OrderByDescending(OrderBy(;
并且错误消息是
无法根据用法推断方法"System.Linq.Enumerable.OrderByDescending(System.Collections.Generic.IEnumerable,System.Func("的类型参数。请尝试显式指定类型参数。
public IQueryable<Project> getProjects([ViewState("OrderBy")]String OrderBy = null)
{
ApplicationServices objServices = new ApplicationServices();
var lstProject = objServices.getProjects();
if (OrderBy != null)
{
switch (sortDirection)
{
case SortDirection.Ascending:
lstProject = lstProject.OrderByDescending(OrderBy);
break;
case SortDirection.Descending:
lstProject = lstProject.OrderBy(OrderBy);
break;
default:
lstProject = lstProject.OrderByDescending(OrderBy);
break;
}
}
return lstProject;
}