Why does Html.ActionLink render "?Length=4"

Question

I'm VERY confused as to why this code

Html.ActionLink("About", "About", "Home", new { hidefocus = "hidefocus" })

results in this link:

<a hidefocus="hidefocus" href="/Home/About?Length=4">About</a>

The hidefocus part is what I was aiming to achieve, but where does the ?Length=4 come from?

This behavior also appears with the Html.BeginForm() methods. — Jonathon Watney, Dec 08 '11 at 18:44

roryf · Accepted Answer · 2009-05-06T14:52:28.973

344

The Length=4 is coming from an attempt to serialize a string object. Your code is running this ActionLink method:

public static string ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, object routeValues, object htmlAttributes)

This takes a string object "Home" for routeValues, which the MVC plumbing searches for public properties turning them into route values. In the case of a string object, the only public property is Length, and since there will be no routes defined with a Length parameter it appends the property name and value as a query string parameter. You'll probably find if you run this from a page not on HomeController it will throw an error about a missing About action method. Try using the following:

Html.ActionLink("About", "About", new { controller = "Home" }, new { hidefocus = "hidefocus" })

edited May 06 '09 at 14:52

answered May 05 '09 at 10:45

roryf

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@Blah_Blah these days I don't use this at all, prefer writing my own tags and just using Url.Action("Action", "Controller") – roryf May 13 '13 at 14:42
@roryf no worries ... this was used in a code review as a best practices, they didn't check the date. There really should be a way to filter the stackoverflow by date ... – THBBFT May 13 '13 at 15:32
1

Great answer. Just to add this also happens on Html.BeginRouteForm for the same reason. Html.BeginRouteForm("Route", "Action", FormMethod.Post)) Should be Html.BeginRouteForm("Route", new{ action = "AgentSignUp"}, FormMethod.Post) that gets rid of the weird length thing – radm4 Dec 04 '13 at 15:58
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Also happens with `Url.Action()`. Changing from `Url.Action("Action", "Controller", new { area = "" })` to `Url.Action("Action", new { controller = "Controller", area = "" })` keeps the Length property from showing up. – John Washam Sep 05 '14 at 18:42
2

To avoid those kinds of situation, you can always specify what parameters you are passing, like: `Html.ActionLink("About", "About", "Home", routeValues: null, htmlAttributes: new { hidefocus = "hidefocus" })` – Mar 13 '15 at 16:52
Thanks! :) That was a gotcha, it was looking for routevalues. – André Snede Jan 16 '16 at 01:50

score 200 · Answer 2 · edited Aug 23 '16 at 19:34

200

The way I solved this is was adding a null to the fourth parameter before the anonymous declaration (new {}) so that it uses the following method overload: (linkText, actionName, controllerName, routeValues, htmlAttributes):

Html.ActionLink("About", "About", "Home", null, new { hidefocus = "hidefocus" })

edited Aug 23 '16 at 19:34

Window

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answered Nov 02 '10 at 19:19

Manuel Castro

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This is the best answer if you're not linking between Areas. If you need to specify the area for the link, you would need to specify the routeValues with the `controller` and the `area` to keep the Length property from showing up in the URL. – John Washam Sep 05 '14 at 18:43
@JohnWasham Actually, you don't need to specify the controller in the `routeValues` but only the area. For example: `Html.ActionLink("About", "About", "Home", new {@area = "Admin"}, new { hidefocus = "hidefocus" })` – Mar 13 '15 at 16:55
1

@epiplon, the reason I specify the controller like that is because if you ever don't include htmlAttributes as the last argument of `ActionLink`, MVC will include a weird `Length=x` parameter at the end of the URL. For instance, put this on a page, then view the source of your page, and you'll see what I mean: `@Html.ActionLink("About", "About", "Home", new { area = "Admin" }, new { hidefocus = "hidefocus" })` `@Html.ActionLink("About", "About", "Home", new { area = "Admin" })` But if you put the `controller` entry in the `routeValues`, it will never put `Length=x` in the URL. – John Washam Mar 13 '15 at 19:18
@epiplon, you also don't need to use `@` in `@area = "Admin"`, just so you know. – John Washam Mar 13 '15 at 19:21

score 90 · Answer 3 · edited Oct 05 '15 at 18:57

90

You forgot to add the HTMLAttributes parm.

This will work without any changes:

Html.ActionLink("About", "About", "Home", new { hidefocus = "hidefocus" },null)

edited Oct 05 '15 at 18:57

Matt Hanson

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answered May 26 '12 at 20:00

Jesse Rose

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I don't know,why this is not worked for me.i tried with "new{hidefocus=""}",And this works for me. – Naredla Nithesh Reddy May 09 '18 at 18:25

score 29 · Answer 4 · 2009-05-05T10:52:32.523

29

The parameters to ActionLink are not correct, it's attempting to use the "Home" value as a route value, instead of the anonymous type.

I believe you just need to add new { } or null as the last parameter.

EDIT: Just re-read the post and realized you'll likely want to specify null as the second last parameter, not the last.

edited May 05 '09 at 10:52

answered May 05 '09 at 10:43

1

BTW They should remove one method as it's not possible to use it! – Marc Climent Jun 19 '09 at 07:50

score 5 · Answer 5 · answered Jun 15 '14 at 13:48

5

Html.ActionLink("About", "About", "Home", new { hidefocus = "hidefocus" }, new { })

This will take the overload: string linkText, string actionName, string controllerName, Object routeValues, Object htmlAttributes

answered Jun 15 '14 at 13:48

user2254436

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score 3 · Answer 6 · answered May 10 '12 at 16:08

3

Just remove "Home" (name of the controller) so that the code would be:

Html.ActionLink("About", "About", new { hidefocus = "hidefocus" })

answered May 10 '12 at 16:08

Fil

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No, you need to change "Home" for null – Gjaa Oct 07 '20 at 20:53

score 3 · Answer 7 · edited Dec 08 '15 at 12:25

3

Kindly use right overloaded method with five (5) parameters. Example:

@using (@Ajax.BeginForm("Register", "Account", null,
    new AjaxOptions
    {
        HttpMethod = "POST",
        OnSuccess = "OnSuccess",
        OnFailure = "OnFailure",
        OnBegin = "OnBegin",
        OnComplete = "OnComplete"
    }, new { @class = "form-login" }))

edited Dec 08 '15 at 12:25

Tunaki

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answered Dec 08 '15 at 12:24

Omveer singh maurya

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adding **null** after controller name was helpful in my case. – Munam Yousuf Dec 27 '16 at 07:46
This is effectively the same answer as @Jesse's answer with the added bonus that it covers the Ajax version, which is not what the OP asked for, but it is related to the same issue. – gcoulby Aug 27 '17 at 13:28

score 2 · Answer 8 · edited Apr 21 '21 at 18:11

2

This worked fine

@Html.ActionLink("Informationen", "About", "Home", new { area = "" }, new { @class = "nav-link" })

added new { area = "" }.

edited Apr 21 '21 at 18:11

M-Chen-3

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answered Apr 21 '21 at 17:01

elSchick

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score 1 · Answer 9 · answered Nov 24 '13 at 20:33

As Jonathon Watney pointed out in a comment, this also goes for

Html.BeginForm()

methods. In my case, I was in a Create.cshtml targeting the post request of the corresponding controller + Create action and had

using (Html.BeginForm("Create")) {
  @Html.AntiForgeryToken()
  ...
}

which was adding the querystring "?Length=6" to the form action when rendered. Hinted by roryf's approved answer and realizing the string length of "Create" is 6, I finally solved this by removing the explicit action specification:

using (Html.BeginForm()) {
      @Html.AntiForgeryToken()
      ...
    }

score 1 · Answer 10 · answered May 19 '15 at 17:15

1

With attribute names:

 @Html.ActionLink(linkText: "SomeText", actionName: "SomeAction", controllerName: "SomeControllerName", routeValues: new { parameterName = parameterValue}, htmlAttributes: null)

answered May 19 '15 at 17:15

usefulBee

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score 0 · Answer 11 · answered Aug 09 '18 at 15:47

Perhaps others had the same issue and need to supply a class value via HTMLAttributes parm. Here's my solution:

@Html.ActionLink("About", "About", new { controller = "Home", area = "" }, new { hidefocus = "hidefocus", @class = "nav-item nav-link" })

Irf · Answer 12 · 2020-04-17T14:35:30.153

Search for an answer to my question landed me here, basically it's the selection of correct overload of @Html.ActionLink which matters.
I was selecting an overload which didn't exist, (without the last null), and MVC had no such overload, resulting in a false URL something like the OP mentioned.

A personal note: you can use anonymous types doesn't mean you can use any of the overloads- which do not exist? - make certain: it has to be defined!
- Came here in times of MVC 5.2

Why does Html.ActionLink render "?Length=4"

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