We know that in MVC, a CheckBoxFor will generate a checkbox with a value="true" and a hidden with a value=false. Both input controls will share the same name.
It is very reasonable because the form will be able to POST a false value if the box is unchecked. And the model binder will ignore the hidden input when the checkbox return a true.
But now i have overridden the form submit event in order to send the form data into a WebAPI controller in JSON format.
When serializing the form data, there is no mechanism to parse the relationship between the checkbox and the hidden correctly. Therefore, when unchecked, it returns a false, which is okay. But when checked, it returns a {true, false} instead of true, because the serializeArray() function goes through every input and find two values goes to a same name.
The question is: What is the best way to correct it?
My solution to this problem was to write my own HtmlHelper method that renders a single <input type="checkbox" /> tag. Any other solution just seemed too hacky.
You can use dotPeek or .NET Reflector to look at how the Microsoft Team created the HtmlHelper.CheckboxFor method if you need any help accomplishing that task.
The 2 tag approach was taken to prevent MVC action parameters from throwing an exception when a "bool" parameter did not have a matching parameter sent to the controller (an unchecked checkbox doesn't send any value).
I am using a strongly typed model for my view. I have a disabled text box whose value I update using javascript. The textbox is rendered using this
<%: Html.TextBoxFor(model => model.TotalAmount, new { disabled = "disabled"})%>
This renders a textbox with NAME and ID as 'TotalAmount'. TotalAmount is also a property on my model that binds to this view.
The javascript to update its value in the view is like this within its function:
document.getElementById('TotalAmount').value = {assigning new value here};
The function does get called and I can see the value in the disabled textbox when I change some value in another editable textbox. However, when I post this form to my action method as below :
[HttpPost]
public ActionResult Process (ProcessVM FormPostVM)
{
}
the disabled textbox property [TotalAmount] still has the old value but the editable textbox which I modified contains the new value I entered. Why does the disabled textbox not contain the javascript updated value?
I tried using
ModelState.Remove("TotalAmount");
in the action method above, but as I already figured it didn't work.
Any clues, tips?
Thanks for your time....
HTML input elements such as textboxes that have the disabled="disabled" attribute will never send their values to the server when the form is submitted. If you want to send the value to the server while still disabling the user from changing it you could make the textbox readonly:
<%= Html.TextBoxFor(model => model.TotalAmount, new { #readonly = "readonly" }) %>
Disabled inputs are never sent in a form submit, try using readonly attribute instead or hidden inputs
Disabled fields don't get posted. Try having a hidden form field that will send the value to the server, and set both TotalAmount and the hidden form field. On the server, use the value for the hidden field instead.
On a side note, since this looks like the order total, this is something I would recalcuate on the server rather than opening up the possibility of someone hacking the html and getting a discount on their product.
EDIT:
To the other's points, I'd forgotten about the readonly attribute. That will work too.
If you change it to use readonly rather than disabled, then this should give you the same functionality, but post the value.
Browsers don't post values back in disabled input controls, as you've discovered. Probably the easiest way to work around this is to hook onto form submission, and re-enable the input as the form is being submitted; the user won't have a chance to edit the value, and it should get posted with the rest of the request.
i think the last issue described it : please check it out :
Retrieving the value of a asp:TextBox
I have a view with a form that is mapped to a ViewModel. I have 2 submit buttons in the form. When the form is submitted using 1 of the buttons, some of the fields in the form are going to be empty - is it possible to avoid validating the empty fields when the form is submitted using this 1 button? (Using the other button I would like to keep the usual validation rules).
Unfortunately I cannot seperate the fields that I expect to be empty into a seperate ViewModel because both models would have a common field that always needs to be populated.
Any ideas on this? Any help would be much appreciated.
Many thanks.
James
It is possible, but
You will not be able to use clients-side validation
You will not be able to use data annotation attributes like Required etc and you probably need your own validation (or as option you may mark only properties are required in both cases and validate other properties manually)
You need to set different values for name attributes of your submits
<input type="submit" name="first-submit" value="First action" />
<input type="submit" name="second-submit" value="Second action" />
Then you may declare parameter of type FormCollection in your action method. Depends on which button was pressed it will contain first-submit key or second-submit key. Now you can alter your validation logic depends on this.
I have seen lots of questions relating to this topic.
I am using asp.net MVC 1.0
Problem area
If I use
<%= Html.CheckBox("Status", true) %>
Then why It renders like
<input checked="checked" id="Status" name="Status" type="checkbox" value="true" /><input name="Status" type="hidden" value="false" />
I put this in foreach loop and I have 5 rows.
when I submit form with true,true,true,false,false
then I get true,false,true,false,true,false,false,false
i.e. for false => false.
for true => true,false
If I use
<input type="checkbox" value="true" name="Status" checked="checked" />
Then I don't get unchecked one's.
so how do I overcome form this problem?
Please don't post answer with using loop in formcollection object and checking each key!
I know this isn't the elegant one but this is what I did:
collection["response"].Replace("true,false", "true").Split(',').ToList();
In your example, when you submit form with true,true,true,false,false and you get
true,false,true,false,true,false,false,falseit is interesting to note that you are not actually getting eight values back, but five arrays that merely looks like this is the case because all of the values are joined.
I know you asked to not get a loop for your answer, but I can use one to demonstrate what is really happening here:
foreach (string key in postedForm.AllKeys) {
// "value" will contain a joined/comma-separated list of ALL values,
// including something like "true,false" for a checked checkbox.
string value = postedForm[key].GetValue;
// "values" will be an array, where you can access its first element,
// e.g., values[0], to get the actual intended value.
string[] values = postedForm.GetValues(key);
}
So, for your checked boxes, you'll get a values array with two elements, and for unchecked boxes, you'll get just a single-element array.
Thus, to answer your question how do you overcome this problem, the answer lies in using GetValues rather than GetValue, and thinking of your posted fields as arrays rather than strings.
Best of luck!
Personally I think having to check for "true,false" everywhere on the server is a pain. I wrote a jquery fix that will remove the extra hidden field created by the Html.Checkbox helper when a box is checked, then add it back if the box is unchecked. Server values will always be "true" or "false". Checkbox lists are kind of subjective in how you want them to act, which I discuss, but I'm removing "false" from the value set, which means the form value will be excluded if all boxes in the list are unchecked.
http://www.mindstorminteractive.com/blog/?p=386
I've had pretty good success using this technique. Please let me know if you try it out and have issues.
You'll have to do your own model binding for the CheckBox values.
Get the list of values from the FormCollection or Request.Form for that CheckBox id and replace true,false with true:
string chkBoxString = Request.Form["checkboxID"].Replace("true,false", "true")
Now you have a list of whether a CheckBox was selected or not.... do the rest yourself :)
It renders so because default binder requires the FormCollection to have a value for nonnullable parameters. Using this technique we are sure that the value will be sent even the checkbox is not checked (by default the value sent only when it's checked). If you use this controller method with just one html input you'll get error on form post with unchecked checkbox (value of checkbox will not be posted and binder will not know what to use for value of isItemSelected):
public ActionResult SomeActionMethod(bool isItemSelected)
You can try use something like this with just one html input:
public ActionResult SomeActionMethod(bool? isItemSelected)
But in this case isItemSelected will be null or will be true. And it will never become false.
Well there are couple of ways you can do based on your requirement.
I use this method.
<input type="checkbox" value="<%= item.ID %>" name="check" checked="checked")" />
This is may checkboxes.
On server side I will also have array of ID's of item in the model.
So I check it whether it is in array
var strArray = form["checkbox"]; //Request.form["checkbox"] or "FormCollection form" in action parameter; array of ID's in comma separated string.
Different people have different tests.
this was intended to use for just just simple CheckBox, what you want is checkboxList, which is not yet cover in the API of ASP.net MVC
If you looking for some thing like checkboxlist, maybe you should write your own helper, provide you understand HTML well..
That's it! :)
Easier just to check whether AttemptedValue.Contains("true") - it will, if it's checked, not if it's unchecked....
in the View :
<input id="radio5" type="checkbox" name="rb_abc" value="5"/>
Controller:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult YourForm(FormCollection fc)
{
if (fc["rb_abc"] == "on")
{
//Hey .. you have selected a Radio Button.. just kidding.. its a CheckBox
}
}
To get checkbox value even it is true or false
var boolValue = bool.Parse(collection.GetValues("checkboxID")[0])
I am using Html.CheckBox(). The resulting HTML is:
<input id="IsMultiGraph" name="IsMultiGraph" value="true" type="checkbox">
<input name="IsMultiGraph" value="false" type="hidden">
On the server I have an Action which is accepting the form post information and using a custom IModelBinder to bind the form results to one of my models. Here is a snippet of the code I am running in the IModelBinder:
bool isMultiGraph;
if (!bool.TryParse(bindingContext.HttpContext.Request["IsMultiGraph"], out isMultiGraph))
bindingContext.ModelState.AddModelError("IsMultiGraph", "Invalid boolean for \"IsMultiGraph\""); //this should not ever happen unless someone is programatically posting
result.IsMultiGraph = isMultiGraph;
The problem is that since Html.CheckBox() is rendering a checkbox as well as a hidden input field if I change the state of the textbox the postback value is doubled (ie. "true,false").
I understand why this is done and I'm looking for the best way to parse the current value of the CheckBox during a postback (checked = true, unchecked = false). Is there another helper method in MVC for this or should I just write my own?
One way is to use the GetValues method of the NameValueCollection class in order to get the first value of the array property like this:
bindingContext.HttpContext.Request.Form.GetValues("IsMultiGraph")[0]