Asp.Net Mvc 2 Checkbox always false in model

Question

I have a checkbox like this:

<%= Html.CheckBoxFor(x => x.IsSendingQualitySurvey) %>/>

when checking the checkbox and submitting, I get the typical 2 form values:

IsSendingQualitySurvey: true
IsSendingQualitySurvey: false

This is perfectly valid for the way the mvc modelbinder handles checkboxes.

Then in the controller action:

[HttpPost]
public ActionResult Edit(Guid id, TicketEditViewModel ticketEditViewModel)

ticketEditViewModel.IsSendingQualitySurvey (a normal bool) is always false.

I don't have any custom model binders and it works elsewhere. Strangely enough I've had the same problem in another view quite a while ago, where I had to create the input manually, looks like this:

<input type="checkbox" value="true" name="<%=Html.NameFor(x => x.IsRequestingVisit) %>" id="<%=Html.NameFor(x => x.IsRequestingVisit) %>" />

This worked, but when I copied the exact same over to the other view, the value is still always false.

Wheres the catch?

Thanks.

Will · Accepted Answer · 2012-01-17 17:36:04Z

1

EDIT Got the wrong end of the stick... sorry

Have you tried fetching the raw value out of the post data like so:

In the Controller:

[HttpPost]
public ActionResult Edit(Guid id, TicketEditViewModel ticketEditViewModel,
                                            FormCollection fc) {

    if(fc["IsSendingQualitySurvey"].Contains("true")) {
        //Do something.
    }
}

In the View:

<%= Html.CheckBoxFor(model => model.IsSendingQualitySurvey) %>

Hope this helps..

answered Jan 17, 2012 at 17:36

Will

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1 Comment

sharp johnny Over a year ago

I didn't find away around it, so I used Request.Form["IsSendingQualitySurvey"].Contains("true"), even though it's soo ugly =(

Nick Bork · Accepted Answer · 2012-01-17 17:43:45Z

1

The model binder likely wont pickup the binding. My advice is to change your action to:

 [HttpPost] 
 public ActionResult Edit(Guid id, TicketEditViewModel model)

The model binder wants to find properties in the Request that have a prefix that match your object name. Since there is no naming prefix on the client side, there are no properties with the prefix "ticketEditViewModel".

The alternative is to name a variable on the page:

 <% var ticketEditViewModel = Model; %>
 <%= Html.CheckBoxFor(model => ticketEditViewModel.IsSendingQualitySurvey) %>

edited Jan 17, 2012 at 17:43

answered Jan 17, 2012 at 17:28

Nick Bork

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5 Comments

sharp johnny Over a year ago

I forgot to say that the model is actually filled the right way, just the one property missing. Also I dont think the model binder cares about the prefix as its not even transfered to the resulting input, are you sure about this?

Nick Bork Over a year ago

The model binder looks at the values contained in the Query String or Form Collection and attempts to bind the properties by name. Your ID/Name fields on the client side (generated by the HTML helpers) contain the namespace and are direct result of the naming convention you use for variables. If you have complex models or you create variables on the page you'll notice that the HTML Helper will generate prefixes on your controls that match your variable names. There may be some logic in the model binder that will cover mismatching names but I can't say for sure without digging out a reflector.

sharp johnny Over a year ago

Hmm, so maybe because I'm passing two parameters, the binder might introduce namespaces and in that case not finding the model parameter because of my conventions? Haven't seen those namespaces yet. I'll look into that tomorrow, thanks so far.

sharp johnny Over a year ago

My model is simple, so there are no namespaces introduced and stuff. The form collection has has [true, false], like expected. Renaming the parameter has no impact, and introducing a variable on the page like you suggested is not a solution(too ugly), the same as reading out the value from the formcollection... The id parameter comes from the routing, the model is filled right. I don't get what's going on with the model binder, maybe I'm missing something really trivial?

Nick Bork Over a year ago

I don't have an answer for you without having your project to do some testing but I did find this page: forums.asp.net/t/1314753.aspx You'll notice that Dinoboy (5th post) gives some code on how to invoke the model binder on a property. I would suggest you take that snippet and change the field name and try to see if you can get the MB to parse your property correctly and go from there. Keep in mind that the default value for a bool property is "false".

knowwebapp.com · Accepted Answer · 2013-04-10 03:18:13Z

0

For following model:

public class StartViewModel {

public string Id{ get; set; }

public string Name { get; set; }

public bool Accept { get; set; }

}

-> Accept =false.

The solution: Change public bool Accept { get; set; } to public string Accept { get; set; }

When submit, if checkbox is checked, The "Accept" value = "on". You can dectect checked value by the way.

answered Apr 10, 2013 at 3:18

knowwebapp.com

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Yulian · Accepted Answer · 2016-05-10 12:04:50Z

0

I'm not sure whether this will work for you, but in fact it solved the same issue for me. Try adding (not replacing) a hidden field for the same model's property like this:

@Html.HiddenFor(x => x.IsSendingQualitySurvey)

answered May 10, 2016 at 12:04

Yulian

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