Geek asks and answers

How do you override Html.ActionLink?

Often I need to display ActionLink with the contents from the database (imagine a combination of identifiers / names), so I will put the following in my opinion:

        @foreach (var row in Model)
        {
            <li>@Html.ActionLink(row.Name, "Action", "Controller", new { id = row.Id })</li>
        }

However, this throws an exception if the Name is an empty string. Is there any way to prevent this. I would like to override ActionLink, but this is an extension, so I cannot override.

Any suggestions?

Edit:

Firstly, I do not control the data, or I would make sure that the "Name" field is required and always filled. Unfortunately, this is not the case.

Secondly, I understand that the user has nothing to click, but I believe that rendering an empty link is a better alternative than providing them with YSOD.

+5
source share
3 answers

, .

CustomHtmlHelper ActionLink :

public abstract class CustomWebViewPage<T> : WebViewPage<T>
{
    public new CustomHtmlHelper<T> Html { get; set; }

    public override void InitHelpers()
    {
        Ajax = new AjaxHelper<T>(ViewContext, this);
        Url = new UrlHelper(ViewContext.RequestContext);

        //Load Custom Html Helper instead of Default
        Html = new CustomHtmlHelper<T>(ViewContext, this);
    }
}

HtmlHelper ( ActionLink Reflector LinkText:

public class CustomHtmlHelper<T> : HtmlHelper<T>
{
    public CustomHtmlHelper(ViewContext viewContext, IViewDataContainer viewDataContainer) :
        base(viewContext, viewDataContainer)
    {
    }

    //Instance methods will always be called instead of extension methods when both exist with the same signature...

    public MvcHtmlString ActionLink(string linkText, string actionName)
    {
        return ActionLink(linkText, actionName, null, new RouteValueDictionary(), new RouteValueDictionary());
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, object routeValues)
    {
        return ActionLink(linkText, actionName, null, new RouteValueDictionary(routeValues), new RouteValueDictionary());
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, string controllerName)
    {
        return ActionLink(linkText, actionName, controllerName, new RouteValueDictionary(), new RouteValueDictionary());
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, RouteValueDictionary routeValues)
    {
        return ActionLink(linkText, actionName, null, routeValues, new RouteValueDictionary());
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, object routeValues, object htmlAttributes)
    {
        return ActionLink(linkText, actionName, null, new RouteValueDictionary(routeValues), AnonymousObjectToHtmlAttributes(htmlAttributes));
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes)
    {
        return ActionLink(linkText, actionName, null, routeValues, htmlAttributes);
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, string controllerName, object routeValues, object htmlAttributes)
    {
        return ActionLink(linkText, actionName, controllerName, new RouteValueDictionary(routeValues), AnonymousObjectToHtmlAttributes(htmlAttributes));
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, string controllerName, RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes)
    {
        return MvcHtmlString.Create(GenerateLink(ViewContext.RequestContext, RouteCollection, linkText, null, actionName, controllerName, routeValues, htmlAttributes));
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, string controllerName, string protocol, string hostName, string fragment, object routeValues, object htmlAttributes)
    {
        return ActionLink(linkText, actionName, controllerName, protocol, hostName, fragment, new RouteValueDictionary(routeValues), AnonymousObjectToHtmlAttributes(htmlAttributes));
    }

    public MvcHtmlString ActionLink(string linkText, string actionName, string controllerName, string protocol, string hostName, string fragment, RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes)
    {
        return MvcHtmlString.Create(GenerateLink(ViewContext.RequestContext, RouteCollection, linkText, null, actionName, controllerName, protocol, hostName, fragment, routeValues, htmlAttributes));
    }
}

, , pageBaseType int Views/Web.config WebViewPage:

  <system.web.webPages.razor>
    ...
    <pages pageBaseType="Fully.Qualified.Namespace.CustomWebViewPage">
    ...
    </pages>
  </system.web.webPages.razor>

, - .

+9

, , - , . : <a href="someUrl"></a> , .

, " " , .

@foreach (var row in Model)
        {
            <li>@Html.ActionLink(string.isNullOrEmpty(row.Name) ? "No Name" : row.Name, "Action", "Controller", new { id = row.Id })</li>
        }

@Html.ActionLink, @Html.Helper

 public static IHtmlString ActionLinkCheckNull(this HtmlHelper htmlHelper, string linkText, string action, string controller, object routeValues, object htmlAttributes)
        {
            var urlHelper = new UrlHelper(htmlHelper.ViewContext.RequestContext);
            var anchor = new TagBuilder("a") { InnerHtml = string.IsNullOrEmpty(linkText) ? "No Name", linktext };
            anchor.Attributes["href"] = urlHelper.Action(action, controller, routeValues);
            anchor.MergeAttributes(new RouteValueDictionary(htmlAttributes));
            return MvcHtmlString.Create(anchor.ToString());
        }

"" web.config , , using . :

<add namespace="Core.Extensions"/>


 @Html.ActionLinkCheckNull(row.Name, "Action", "Controller", new { id = row.Id })
+3

, , :

private static string GenerateLinkInternal(RequestContext requestContext, RouteCollection routeCollection, string linkText, string routeName, string actionName, string controllerName, string protocol, string hostName, string fragment, RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes, bool includeImplicitMvcValues)
{
    string value = UrlHelper.GenerateUrl(routeName, actionName, controllerName, protocol, hostName, fragment, routeValues, routeCollection, requestContext, includeImplicitMvcValues);
    TagBuilder tagBuilder = new TagBuilder("a")
    {
        InnerHtml = (!string.IsNullOrEmpty(linkText)) ? HttpUtility.HtmlEncode(linkText) : string.Empty
    };
    tagBuilder.MergeAttributes<string, object>(htmlAttributes);
    tagBuilder.MergeAttribute("href", value);
    return tagBuilder.ToString(TagRenderMode.Normal);
}

, , , . :

public static MvcHtmlString ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName, RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes)
{
    if (string.IsNullOrEmpty(linkText))
    {
        throw new ArgumentException(MvcResources.Common_NullOrEmpty, "linkText");
    }
    return MvcHtmlString.Create(HtmlHelper.GenerateLink(htmlHelper.ViewContext.RequestContext, htmlHelper.RouteCollection, linkText, null, actionName, controllerName, routeValues, htmlAttributes));
}

technically speaking, the code must be protected, but it is like a function.

Here is a workaround for you, but you will need to create your own extension method ActionLinklike this and put it in a code file somewhere in the project:

using System;
using System.Collections.Generic;
using System.Web.Mvc.Resources;
using System.Web.Routing;
namespace System.Web.Mvc.Html
{
    public static class MyLinkExtensions
    {
        public static MvcHtmlString ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName, int identifier)
        {
            return htmlHelper.ActionLink(string.IsNullOrEmpty(linkText) ? "some default text" : linkText, actionName, controllerName, new { id = identifier });
        }
    }
}

and now your markup looks like this:

@foreach (var row in Model)
{
    <li>@Html.ActionLink(row.Name, "Action", "Controller", row.Id)</li>
}

and you encapsulated the rotation to determine the state linkText, but still display your links on one line.

0
source

More articles:


All Articles