I use mvc html helper checkbox like this:
#Html.DropDownList(item.QuestionId.ToString(),
new SelectList(((DropDownList)item).Options, "OptionId", "Name"),
"Select Please")
and when i submit, in my [http] controller, i can get the value by
[HttpPost]
public ActionResult TestList(FormCollection formCollection)
{
foreach (var res in formCollection.AllKeys)
{
string Selected = null;
Selected = formCollection[res];
}
but when I select "A" for example, I get A, but when I select nothing (it shows "Select Please" as I defined), I want it to be null,but now it's "", it means it has value...I just want it to be like: I submit nothing if I selected nothing, I mean nothing in AllKeys, neither in StringSelected, I want allkeys has nothing if I don't select, thank you
ps:
for e.g:
foreach (var SubItem in ((RadioButtonList)item).Options)
{
#Html.RadioButton(item.SurveyItemId.ToString(), SubItem.OptionId) #SubItem.Name
}
it will show options of a question, if i chose A, i can get A form my controller, i didnt choose B,so in my controller AllKeys, it doesnt contain B or C or D, so i want dropdownlist just like this, if i didnt choose anyone, it wont show "" or something else just like i didnt choose B or C or D, nothing will show in AllKeys
First, that's not a check box. That's a drop down list. Asking questions with correct information is important, or you will get the wrong answers.
Second, this is not possible, and it has nothing to do with MVC, this is done by the browser. There's no way to make the browser submit "null" when you're actually submitting something. There is no concept of "null" in an http post.
The only way you get null is if the value is not posted at all. Otherwise, the model binder could not know the difference between an actual null and when you actually wanted to post an empty string.
You can't even create a custom model binder, because you're bypassing model binding by going directly to the forms collection.
Related
I have never asked a question on StackOverflow before, and never wanted to, but I am desperate, so here we go: I cannot get a saved value to show up as the default value/display in a dropdown.
I set up the list in my controller:
public ActionResult Index()
{
//User Dropdown List
var users = Roles.GetUsersInRole("Manager");
SelectList list = new SelectList(users);
ViewBag.Users = list;
return View();
}
Then in the view an admin can then select one of these users and save it to my database via EF:
#Html.DropDownList("Users", ViewBag.Users as SelectList, "--Select Manager--")
This all works great, however, when you edit this entry, I want the dropdown list to show the current saved manager, not the first name in the list. I was hoping on my edit action that I could pull the current manager out of the database and pass it back into the dropdown as the default selected item, but no go:
public ActionResult Edit(int id = 0)
{
var theOwner = (from v in _db.Location where v.LocationID == id select v.Owner).FirstOrDefault();
var users = Roles.GetUsersInRole("Manager");
SelectList list = new SelectList(users, theOwner);
ViewBag.Users = list;
From all the examples I have read over the last 2 weeks, everyone has had 3 different values to work within their dropdowns, making it possible to use all the overloads in the SelectList method. However, my problem is that I just have this string list with only one item in it, so I can't utilize the overloads as I want.
So does anyone have an idea on how I can get this to work? Thanks a lot in advance for your time on this!
I'm pretty sure that if you modify the second parameter on the line where you create your SelectList, it should work -- it does for me.
Here is what I think the trouble is: Currently you are specifying the second parameter as 'theOwner', which is an object reference from the earlier Linq statement. But the SelectList contains a bunch of strings (the UserNames of the users which match the specified rolename). As a result, the SelectList doesn't 'know' how to match what you specified as the SelectedItem to something in the list of strings it contains.
But if you refine that second parameter so it specifies the USERNAME of the Owner that you just looked up, it should work. However I do not know what the correct property name is from your Location table. If the field you are currently selecting (v.Owner) contains the UserName itself rather than some Key then the syntax would be:
SelectList list = new SelectList(users, theOwner.Owner);
If that column actually contains a key for the User like an int or a Guid then you will have query for the UserName using the key, but the nature of the fix is the same.
Hope that helps.
A quick workaround is not to use #Html.DropDownList but plain html code.
As an example for your case, use the following html code in your View instead of Html.DropDownList helper:
<!-- NOTE: the ID and name attributes of "select" tag should be the same as
the name of the corresponding property in your Model in order for ASP.NET MVC
to edit your Model correctly! -->
<select id="User" name="User">
#foreach (var user in (SelectList)ViewBag.Users)
{
if (user == ViewBag.TheOwner)
{
<option value="#user" text="#user" selected = "selected" />
}
else
{
<option value="#user" text="#user" />
}
}
</select>
Also , for this to work you need to add one more line to your Edit method:
ViewBag.TheOwner = theOwner;
Another solution is also possible using #Html.DropDownListFor() however you haven't shown your model so I can't tell you what exactly to use. When DropDownListFor is used, ASP.NET MVC will select an option automatically based on the value in your model.
I have a dropdownlist in asp.net mvc which is bound using the normal binding syntax
and I can retrieve the "value" in the controller.
But I also need to display the text that is associated with this value.
I can go the hard route and query the db for this associated value.
But I wanted to know if there is an easy way to retrieve the Text as well as the Value in the controller.
Sample code I used
<%= Html.DropDownList("State","Pick a State")%>
which displays
"NJ", "New Jersey" etc.
In Controller
public ActionResult SelectState(string State)
{
// I have value of State (NJ) ...I also need the Text for this
}
Any help would be appreciated.
Thanks
The value that will come as part of the form submission is the value of the dropdown item. To get both, you could change the value to be something like "value delimiter text", so something like "NJ|New Jersey". Then you could parse it in the controller.
I have a usercontrol that is rendering a list of items. Each row contains a unique id in a hidden field, a text and a delete button. When clicking on the delete button I use jquery ajax to call the controller method DeleteCA (seen below). DeleteCA returns a new list of items that replaces the old list.
[HttpPost]
public PartialViewResult DeleteCA(CAsViewModel CAs, Guid CAIdToDelete)
{
int indexToRemove = CAs.CAList.IndexOf(CAs.CAList.Single(m => m.Id == CAIdToDelete));
CAs.CAList.RemoveAt(indexToRemove);
return PartialView("EditorTemplates/CAs", CAs);
}
I have checked that DeleteCA is really removing the correct item. The modified list of CAs passed to PartialView no longer contains the deleted item.
Something weird happens when the partial view is rendered. The number of items in the list is reduced but it is always the last element that is removed from the list. The rendered items does not correspond to the items in the list/model sent to PartialView.
In the usercontrol file (ascx) I'm using both Model.CAList and lambda expression m => m.CAList.
How is it possible for the usercontrol to render stuff that is not in the model sent to PartialView?
Thanx
Andreas
It sounds like the ModelState is the trouble here, as you bind to CAs the ModelState save this values in the background as Attempted Values, so its true the object is no longer present at the Model, but the ModelSate still have the values of the deleted object. You can try a:
ModelState.Clear();
To remove all those old values.
Check in firebug what the response realy is. This way you can see if you have a serverside problem or it is a jquery issue.
I build a drop down list in my aspx page as following
<%= Html.DropDownList("SelectedRole", new SelectList((IEnumerable)Model.roles, "RoleId", "RoleName", Model.SelectedRole), "")%>
it works fine for first Get and the first default value is selected; then I select item from the drop down list and submit the form.
the controller bind the values correctly,
public ActionResult About([Bind] Roles r)
{
//r.SelectedRole = the selected value in the page.
//Roles r = new Roles();
r.roles = new List<Role>();
r.roles.Add(new Role(1, "one"));
r.roles.Add(new Role(2, "two"));
r.roles.Add(new Role(3, "three"));
r.roles.Add(new Role(4, "four"));
r.SelectedRole = null;
return View(r)
}
Then I nullify the selected item and return my view, but still the previous selected Item is selected (although I did nullify it)
Any Idea if I am doing something wrong or it is a bug in MVC?
I am using ASP.NET MVC 1
Thanks
This is the normal behavior of all html helpers: they will look at the POSTed values to perform the binding. This means that you cannot change the value in your controller action and expect it to reflect on the view if you use the standard helpers. If there's a value SelectedRole in the POST it will always be this value used and the last parameter of the drop down completely ignored.
You could write your own helper to achieve this or redirect after the POST.
Hey all, this is a newbie ASP.NET MVC question.
I have a view that has a list of checkboxes and a submit button. On submit it posts to a controller method but I can't figure out how to get the values of the checkboxes. Also, I can't figure out how to get model data that I passed into the view when I'm in the post method, I tried using Html.Hidden but that didn't seem to work.
Here's the code:
http://pastebin.com/m2efe8a94 (View)
http://pastebin.com/m39ebc6b9 (Controller)
Thanks for any input received,
Justin
First thing I noticed is that your hidden fields need to be inside your form. Currently in your view, they are above the BeginForm, so they won't be included in the form submission.
To get the values of the selected check boxes, add an IsOffered parameter to your OfferTrade Action method.
public ActionResult OfferTrade(FormCollection result, List<string> IsOffered)
That parameter will contain a list of the ItemId's for all the checked IsOffered boxes.
The HtmlHelper's CheckBox works differently and I don't like the way it works, so I don't use it.
Making the IsOffered parameter type List<int> should also work if your ItemId field is an integer.
First of all your ItemId and UserId is outside your form:
<%= Html.Hidden("ItemId", Model.ItemIWant.ItemId) %>
<%= Html.Hidden("UserId", Model.ItemIWant.UserId) %>
//...
<% using (Html.BeginForm()) {%>
Secondly you could try to make your Controller action method use "model binding" (if this is also called model binding)
public ActionResult OfferTrade(int ItemId, int UserId, IList<string> IsOfferred)
Edit Just noticed you are not using the HtmlHelper CheckBox so your list will contain only selected items, but a point still:
You might want to look into Phil Haacks post on Model Binding To A List, but there is a small change to this in the RTM version of MVC:
You dont need the ".Index" hidden fields, but then the indexes in the Name fields must be zero-indexed and increasing (by 1).