CheckBoxList Helper for MVC

CheckBoxList Helper for MVC | Tmao Coders

CheckBoxList Helper for MVC | Tmao Coders — Tue, 11 Nov 2008 05:22:57 GMT

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Extending MVC: Returning an Image from a Controller Action

Jeremiah Clark's Blog — Fri, 14 Nov 2008 06:54:48 GMT

So I was thinking tonight, what if I want my MVC application to serve images that are stored in a SQL

re: CheckBoxList Helper for MVC

James — Fri, 20 Feb 2009 16:13:57 GMT

Just what I was looking for - thanks!

re: CheckBoxList Helper for MVC

Peter Duerden — Mon, 18 May 2009 03:24:54 GMT

Not being a strong C# coder I was grateful to find a re-implementation of the Html.CheckBoxList helper that was dropped in MVC Preview 5. I'm beginning to realise how much better my C# is going to have to get to be able to get the best out of ASP.NET MVC. However, after more than 10 years my raw HTML is pretty good ;) and in return for you generously sharing your code though I should point out that the HTML generated is invalid.

It's probably the use of TagRenderMode.Normal but INPUT elements are defined as EMPTY and closing tags are FORBIDDEN. Check the W3C specs at http://www.w3.org/TR/html401/interact/forms.html#edef-INPUT. Also, it's best to associate the text as a LABEL element with the INPUT for accessibility and semantics. For example (hope the HTML makes it via this comment):

To achieve this I modified the TagBuilder section as follows:

TagBuilder inputBuilder = new TagBuilder("input");

if (info.IsChecked) inputBuilder.MergeAttribute("checked", "checked");

inputBuilder.MergeAttributes<string, object>(htmlAttributes);

inputBuilder.MergeAttribute("type", "checkbox");

inputBuilder.MergeAttribute("value", info.Value);

inputBuilder.MergeAttribute("name", name);

inputBuilder.GenerateId(info.Value);

TagBuilder labelBuilder = new TagBuilder("label");

labelBuilder.MergeAttribute("for", inputBuilder.Attributes["id"]);

labelBuilder.InnerHtml = info.DisplayText;

sb.Append(inputBuilder.ToString(TagRenderMode.SelfClosing));

sb.Append(labelBuilder.ToString(TagRenderMode.Normal));

sb.Append("<br />");

re: CheckBoxList Helper for MVC

John Kaster — Tue, 02 Jun 2009 09:58:45 GMT

Thanks for your code contribution. Is there a specific reason you created CheckBoxListInfo instead of reusing the existing SelectListItem class?

re: CheckBoxList Helper for MVC

John Kaster — Tue, 02 Jun 2009 10:13:57 GMT

Also, you said: "The problem with using Html.CheckBox for my scenario arises when you need to get the values in the form ActionMethod. For Html.CheckBox, the form handler is expecting a boolean parameter for each checkbox. An example is show below."

I think you could use FormCollection formValues for this scenario.

re: CheckBoxList Helper for MVC

Andre Nascentes — Wed, 24 Jun 2009 22:54:36 GMT

Hi Jeremiah!

I'm using this helper with the final version of ASP.NET MVC.

The problem is the save method... When I receive a FormCollection, it brings all the checkboxes values.. but only the value.. and I don't know if it's checked or not.

When I receive a string [] it brings me nothing...

Do you know how I can do the save method?

Thanks!

re: CheckBoxList Helper for MVC

Tim Rourke — Wed, 01 Jul 2009 20:23:36 GMT

@Andre Nascentes:

You might try this:

bool bChecked = form[key].Contains("true");

I found it on StackOverflow at http://stackoverflow.com/questions/220020/how-to-handle-checkboxes-in-asp-net-mvc-forms/220073

re: CheckBoxList Helper for MVC

Gerardo Contijoch — Sun, 05 Jul 2009 07:16:29 GMT

Nice implementation, but unfortunately, it doesn't have support for ModelState.

I made a similar custom implementation of CheckListBox based on the CheckBox() extension method from ASP.NET MVC.

If you are interested in it you may find it here:

http://gerardocontijoch.wordpress.com/2009/07/04/un-checkboxlist-que-funciona-en-asp-net-mvc/

The post is in spanish, but I guess nobody will have problem reading the code.

The only limitation I find in my implementation is that the checkstate of the checkboxes can only be loaded from the ModelState and you can't set it by hand.

Great blog, btw!

re: CheckBoxList Helper for MVC

Gerardo Contijoch — Sun, 05 Jul 2009 07:18:03 GMT

I forgot to mention that my implementation have support for ModelState, that's why I mentioned it :P

re: CheckBoxList Helper for MVC

vp — Thu, 09 Jul 2009 17:04:03 GMT

I have used your code. but I am getting the below error "best extension method overload -------" has some invalid arguments...

i have used below code

ViewData.Model - here i have passed lsit..

still am getting invalid argumets error

re: CheckBoxList Helper for MVC

Lauri Larjo — Mon, 07 Sep 2009 17:37:55 GMT

Nice example, works fine. Unfortunately this doesn't support ModelState and thus validation will be a bit harder.

re: CheckBoxList Helper for MVC

jmuir — Sun, 01 Nov 2009 03:08:34 GMT

Great solution for creating a checkboxlist. You just saved me numerous hours of work. Thank you!

re: CheckBoxList Helper for MVC

Chris — Tue, 17 Nov 2009 16:26:00 GMT

Thanks for sharing this. I need my list broken into table columns so I extended this a little further and thought I would share it.

Passing in a new variable I call 'split' that represents the number of columns I want in the table. Code then evenly splits them into table columns which look nice :)

Passing <= 1 or not passing a number makes it work as normal:

Here is the code:

public static string CheckBoxList(this HtmlHelper htmlHelper, string name, List<CheckBoxListInfo> listInfo)

{

return htmlHelper.CheckBoxList(name, listInfo, 0,

((IDictionary<string, object>)null));

}

public static string CheckBoxList(this HtmlHelper htmlHelper, string name, List<CheckBoxListInfo> listInfo, int split)

{

return htmlHelper.CheckBoxList(name, listInfo, split,

((IDictionary<string, object>)null));

}

public static string CheckBoxList(this HtmlHelper htmlHelper, string name, List<CheckBoxListInfo> listInfo,

object htmlAttributes)

{

return htmlHelper.CheckBoxList(name, listInfo, 0,

((IDictionary<string, object>)new RouteValueDictionary(htmlAttributes)));

}

public static string CheckBoxList(this HtmlHelper htmlHelper, string name, List<CheckBoxListInfo> listInfo, int split,

IDictionary<string, object> htmlAttributes)

{

if (String.IsNullOrEmpty(name))

throw new ArgumentException("The argument must have a value", "name");

if (listInfo == null)

throw new ArgumentNullException("listInfo");

if (listInfo.Count < 1)

throw new ArgumentException("The list must contain at least one value", "listInfo");

StringBuilder sb = new StringBuilder();

int colCount = 0;

int count = 0;

int maxItems = listInfo.Count();

if (split > 1)

{

// Begin Table

sb.AppendLine("<table width='100%' border='0'><tr><td>");

}

foreach (CheckBoxListInfo info in listInfo)

{

TagBuilder builder = new TagBuilder("input");

if (info.IsChecked) builder.MergeAttribute("checked", "checked");

builder.MergeAttributes<string, object>(htmlAttributes);

builder.MergeAttribute("type", "checkbox");

builder.MergeAttribute("value", info.Value);

builder.MergeAttribute("name", name);

builder.InnerHtml = info.DisplayText;

sb.Append(builder.ToString(TagRenderMode.Normal));

if (split <= 1)

{

// Skip Table all together....

}

else

{

count ++;

colCount ++;

if (split == colCount)

{

colCount = 0;

sb.Append("</td></tr>");

if (count != maxItems)

{

// Need another row

sb.Append("<tr><td>");

}

else

{

sb.Append("</td><td>");

}

if (split > 1)

sb.Append("</table>");

return sb.ToString();

}