C# 如何向以前创建的对象添加属性

我不确定我想做的是否有意义。我正在尝试制作一个可移植的分页小部件，以便在asp.net mvc中使用

棘手的部分是，我正在为路由值存储一个对象

public class PaginatedList<T> : List<T>
{
    public PaginationData PaginationData { get; private set; }

    public PaginatedList(IQueryable<T> source, int pageIndex, int pageSize)
    {
        PaginationData = new PaginationData( source.Count() , pageIndex, pageSize);
        this.AddRange(source.Skip((PaginationData.PageIndex - 1) * PaginationData.PageSize).Take(PaginationData.PageSize));
    }

}

public class PaginationData
{
    ////////////////////////////////////////////
    public object PageRoute { get; set; } //   <-- object for route values
    ////////////////////////////////////////////
    public bool HasPreviousPage { get { return (PageIndex > 1); } }
    public bool HasNextPage { get { return (PageIndex < TotalPages); } }
    public int PageIndex { get; private set; }
    public int PageSize { get; private set; }
    public int TotalCount { get; private set; }
    public int TotalPages { get; private set; }

    public PaginationData(int count, int pageIndex, int pageSize)
    {
        PageIndex = pageIndex;
        PageSize = pageSize;
        TotalCount = count;
        TotalPages = (int)Math.Ceiling(TotalCount / (double)PageSize);
    }
}

正如你所看到的。。。以上部分视图尚未完成。我专门从事这方面的工作：

            <!--How do I add {page=i} to Model.PageRoute object below?-->
            <%: Html.RouteLink(i.ToString(), Model.PageRoute)%>

---

有办法做到这一点吗？

您可以将PaginationData类修改为如下内容。注意：为了与MVC框架保持一致，我将

PageRoute

属性重命名为

RouteValues

public class PaginationData
{
    private System.Web.Routing.RouteValueDictionary _RouteValues;

    public System.Web.Routing.RouteValueDictionary RouteValues
    {
        get
        {
            if (_RouteValues == null)
            {
                _RouteValues = new System.Web.Routing.RouteValueDictionary();
            }
            return _RouteValues;
        }
        private set { _RouteValues = value; }
    }

    public void SetRouteValues(object routeValues)
    {
        this.RouteValues = new System.Web.Routing.RouteValueDictionary(routeValues);
    }

    public bool HasPreviousPage { get { return (PageIndex > 1); } }
    public bool HasNextPage { get { return (PageIndex < TotalPages); } }
    public int PageIndex { get; private set; }
    public int PageSize { get; private set; }
    public int TotalCount { get; private set; }
    public int TotalPages { get; private set; }

    public PaginationData(int count, int pageIndex, int pageSize)
    {
        PageIndex = pageIndex;
        PageSize = pageSize;
        TotalCount = count;
        TotalPages = (int)Math.Ceiling(TotalCount / (double)PageSize);
    }
}

或

使用扩展方法合并RouteValueDictionary的替代方法 下面是一些扩展方法，它们为RouteValueDictionary提供了一些功能

public static class RouteValueExtensions
{
    public static void Merge(this RouteValueDictionary routeValuesA, object routeValuesB)
    {
        foreach (var entry in new RouteValueDictionary(routeValuesB))
        {
            routeValuesA[entry.Key] = entry.Value;
        }
    }

    public static RouteValueDictionary With(this RouteValueDictionary routeValuesA, object routeValuesB)
    {
        routeValuesA.Merge(routeValuesB);
        return routeValuesA;
    }

    public static RouteValueDictionary With(this RouteValueDictionary routeValues, params object[] routeValuesToMerge)
    {
        if (routeValues != null)
        {
            for (int i = 0; i < routeValuesToMerge.Length; i++)
            {
                routeValues.Merge(routeValuesToMerge[i]);
            }
        }
        return routeValues;
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, object routeValues)
    {
        return new RouteValueDictionary(routeValues);
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, object routeValuesA, object routeValuesB)
    {
        return htmlHelper.RouteValues(routeValuesA).With(routeValuesB);
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, params object[] routeValues)
    {
        if (routeValues != null && routeValues.Length > 0)
        {
            var result = htmlHelper.RouteValues(routeValues[0]);
            for (int i = 1; i < routeValues.Length; i++)
            {
                result.Merge(routeValues[i]);
            }
            return result;
        }
        else
        {
            return new RouteValueDictionary();
        }
    }
}

或

---

缺点是，这种方法会对新的RouteValueDictionary对象进行一些过度的反射和实例化。

我想我可以用HtmlHelper来实现。有什么方法可以避免使用html帮助程序吗？您使用的

似乎有点过火，因为只有一个页面才起作用。当存在多个页面时，它会抛出一个错误：
已添加具有相同键的项。
。似乎我应该使用html助手路径。谢谢您的编辑。我认为如果我不使用助手，我的局部视图中可能会有太多的逻辑。不过非常感谢您提供的信息。RouteValueDictionary正在抛出该错误，因为您正在调用
Add
方法并传入字典中已经存在的键。尝试
Model.RouteValues[“page”]=i取而代之。这在两种情况下都适用：要么添加新密钥，要么更新现有密钥。是的，一个简单的替代方法是合并从多个
对象创建的
RouteValueDictionaries
；作为
HtmlHelper
对象的扩展方法，一些通用的东西是有意义的。。。我没有意识到
Model.RouteValues[key]=value
将同时处理添加和更新。
public class PaginationData
{
    private System.Web.Routing.RouteValueDictionary _RouteValues;

    public System.Web.Routing.RouteValueDictionary RouteValues
    {
        get
        {
            if (_RouteValues == null)
            {
                _RouteValues = new System.Web.Routing.RouteValueDictionary();
            }
            return _RouteValues;
        }
        private set { _RouteValues = value; }
    }

    public void SetRouteValues(object routeValues)
    {
        this.RouteValues = new System.Web.Routing.RouteValueDictionary(routeValues);
    }

    public bool HasPreviousPage { get { return (PageIndex > 1); } }
    public bool HasNextPage { get { return (PageIndex < TotalPages); } }
    public int PageIndex { get; private set; }
    public int PageSize { get; private set; }
    public int TotalCount { get; private set; }
    public int TotalPages { get; private set; }

    public PaginationData(int count, int pageIndex, int pageSize)
    {
        PageIndex = pageIndex;
        PageSize = pageSize;
        TotalCount = count;
        TotalPages = (int)Math.Ceiling(TotalCount / (double)PageSize);
    }
}

Model.RouteValues.Add("key", value);

Model.RouteValues["key"] = value;

public static class RouteValueExtensions
{
    public static void Merge(this RouteValueDictionary routeValuesA, object routeValuesB)
    {
        foreach (var entry in new RouteValueDictionary(routeValuesB))
        {
            routeValuesA[entry.Key] = entry.Value;
        }
    }

    public static RouteValueDictionary With(this RouteValueDictionary routeValuesA, object routeValuesB)
    {
        routeValuesA.Merge(routeValuesB);
        return routeValuesA;
    }

    public static RouteValueDictionary With(this RouteValueDictionary routeValues, params object[] routeValuesToMerge)
    {
        if (routeValues != null)
        {
            for (int i = 0; i < routeValuesToMerge.Length; i++)
            {
                routeValues.Merge(routeValuesToMerge[i]);
            }
        }
        return routeValues;
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, object routeValues)
    {
        return new RouteValueDictionary(routeValues);
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, object routeValuesA, object routeValuesB)
    {
        return htmlHelper.RouteValues(routeValuesA).With(routeValuesB);
    }

    public static RouteValueDictionary RouteValues(this HtmlHelper htmlHelper, params object[] routeValues)
    {
        if (routeValues != null && routeValues.Length > 0)
        {
            var result = htmlHelper.RouteValues(routeValues[0]);
            for (int i = 1; i < routeValues.Length; i++)
            {
                result.Merge(routeValues[i]);
            }
            return result;
        }
        else
        {
            return new RouteValueDictionary();
        }
    }
}

Html.RouteLink(i.ToString(), Html.RouteValues(Model.PageRoute, new { page = i }))

Html.RouteLink(i.ToString(), Html.RouteValues(Model.PageRoute).With(new { page = i }))