I have a ListBox implemented as below.
#if (Model.SelectListVendorBranchSearched != null )
{
#Html.ListBoxFor(model => model.SelectedVendorBranchLeft, Model.SelectListVendorBranchSearched, new {#class="listbox", #size ="10" })
}
But when the form is posted back the viewModel object does not have the original Data Source that the list was bound to. But it has the selected items posted back.
Is that the right behavior?
Let me try to explain what I am trying to achive.
I am trying to implement the following in ASP.NET MVC.
I have a search functionality that populates a list box say List box A. Now I need to select some items in the List Box A and move the items to another List Box say List Box B. Then do another search that refreshes the List Box A with fresh results. Then again select some more items in the List Box A and append to the items already in List Box B. In the end get the items in the List Box B and save it to DB. How can I do this without any JavaScript?
Related
Is there a way to pre-populate a MultiSelectList with selected items?
Example:
I have a single View that has the following ListBoxFor that will cause the page to update what it's displaying by allowing filtering of Model.Companies.
#Html.ListBoxFor(m => m.SelectedCompanies, new MultiSelectList(Model.Companies, "IdString", "CompanyName")
What I'd like to have happen is after the update, the MultiSelectList will have the items that were selected before the page updated and refreshed. Does that mean I need to return SelectedCompanies with what was selected, or is there another way?
I am using the javascript library Chosen for usability of the ListBox on the client side, but I don't think that this affects what I'm trying to do.
Sometimes, JS libaries can interfere with your desired results. I can't speak for Chosen JS library, but inspect the markup and see how it renders. As long as it still has the listbox on the client (it must have some input element defined somewhere; my guess it hides it and updates the values as they are selected), then yes it should integrate fine.
However, when the controller posts back, you have to repopulate the Model.SelectedCompanies property with whatever values came back from the POST operation to the controller. The property should still have the selected companies if you return a View from the POST operation. If you are using a RedirectToAction instead, you'd have to store the selections in TempData.
I am using ASP.NET MVC3, Jquery, and Kendo UI MVC Wrappers.
I have a simple Kendo UI drop down. It is a nullable drop down so I have the .OptionLabel property set to " ".
There are 2 scenarios when I load the page:
1.) The data for the drop down is supplied by the controller.
2.) The data for the drop down is not supplied by the controller in which case I am giving it an empty list
Upon the initial load of the page, the only available selection is the nullable option. The user can add more selections to the drop down by using other controls on the page.
When scenario #2 occurs, everything works perfectly fine. I get a drop down list with all of the selections and the null option. The items in the list come via my controller. The drop down works as expected.
When scenario #1 occurs. It seems like the drop down is not initializing or something like that. In this scenario I am sending an empty list from the controller. My expectation is that the drop down should have one selection which is the null option (because of my optionlabel), but instead I get a drop down that is in some sort of disabled state.
So in this situation, is passing an empty list to the drop down the right thing to do or should I be doing something else?
Here is the drop down declaration:
#(Html.Kendo().DropDownList()
.Name("allPeople")
.DataValueField("Id")
.DataTextField("Name")
.OptionLabel(" ")
.DataSource(source =>
{
source.Read(read =>
{
read.Action("_SelectPeopleList", "People");
}).ServerFiltering(true);
})
.Events(e => e
.Change("all_change").Open("all_open"))
)
So just to reiterate, when I hit scenario #2, _SelectPeopleList is returning a list and everything works fine.
When I hit scenario #1, _SelectPeopleList is returning an empty list and the drop down gets in something similar to a disabled state.
Hopefully I was clear enough.
OK, I just discovered a way to do this.
Instead of passing an empty list, I pass a list with id = 0 and and "" as the text field.
And then remove .OptionLabel(" ")
But then, if I have to do it this way, what is the point of having .OptionLabel??
I need solution for my problem on urgent basis, I am new with mvc, knockout please provide me sample code for my problem. any help will be highly appreciated.
suppose I have an observable array in my viewmodel i.e
var viewmodel = {
vendorproviders : ko.observablearray([])
}
where vendorproviders list consist of multiple attributes like id, name, country, address etc
I want to populate that array in my grid where each row will have a select button, when that button is clicked it should post the id to my controller action either by submitting or by ajax call.
Furthor more that grid should be searchable like if there is a separate text box, based on the value of text box grid should display matching providers else display all providers.
when user search for particular provider grid should populate from observable array instead of making call at server again and again to pupulate the observable array.
I would suggest starting here.
http://learn.knockoutjs.com/#/?tutorial=intro
What you are talking about is all the basic functionality of the tools you referenced.
I have a class called "PropertyFeature" which simply contains PropertyFeatureID and Description. It's a proper model created through LINQ to SQL mapped to an SQL Server database table. An example instance/row would be:
PropertyFeatureID: 2
Description: "Swimming Pool"
The number of rows (PropertyFeatures) can of course grow and shrink, and so I want to dynamically render a list of checkboxes so that the user can select any of them.
I can dynamically render the Checkboxes easily enough, with something like:
<%foreach (var Feature in (ViewData["Features"] as IEnumerable<MySolution.Models.PropertyFeature>)) { %>
<%=Html.CheckBox("Features", new { #id = Feature.PropertyFeatureID, #value = Feature.PropertyFeatureID })%><label for="Feature<%=Feature.PropertyFeatureID%>"><%=Feature.Description%></label>
<%}%>
I specify the ID for each checkbox and render the matching label so that the user can intuitively click the label and toggle the checkbox - that works great.
I set the CheckBox's "name" to "Features" so all the checkboxes render with the same name, and the MVC Model Binder piles them into a single collection called "Features" when the form is posted. This works nicely.
Once the form is submitted, I use the checked values and store them, so I need the actual integer values so I know which PropertyFeature is selected, not just a pile of Booleans and field names. So ideally, I want it as an array or a collection that's easy to work with.
I am able to retrieve the selected values from within my Controller method when the button is clicked because I have specified the parameter as int[] Features.
But the problem is that it doesn't maintain state. That is, when I click the submit button and the page reloads (with the form again displayed) I want all of the dynamic checkboxes to retain their checked status (or not). All of the other fields that I've created with Html.DropDownList and Html.TextBox all maintain their states successfully no problems at all on the same page in the same form.
I have spent hours reading all of the other threads and articles on similar issues and there is a lot of talk about using ICollection and IDictionary to bundle things up and include a Boolean value for each item so that it can maintain the checkbox state. But I don't 100% grasp how to use that in the context of my own personal example. I would like to keep the solution really simple and not have to code up pages of new classes just to maintain my checkbox state.
What is the cleanest and proper way to do this?
I got it working after much playing around with the various different approaches.
In the view:
<%string[] PostFeatures = Request.Form.GetValues("Features");%>
<% foreach (var Feature in (ViewData["AllPropertyFeatures"] as
IEnumerable<MySolution.Models.PropertyFeature>))
{ %>
<input type="checkbox" name="Features"
id="Feature<%=Feature.PropertyFeatureID.ToString()%>"
value="<%=Feature.PropertyFeatureID%>"
<%if(PostFeatures!=null)
{
if(PostFeatures.Contains(Feature.PropertyFeatureID.ToString()))
{
Response.Write("checked=\"checked\"");
}
}
%> />
<label for="Feature<%=Feature.PropertyFeatureID%>">
<%=Feature.Description%></label> <%
} %>
In the receiving controller method:
public ActionResult SearchResults(int[] Features)
This method has a number of advantages:
Allows labels to be clicked to toggle the corresponding checkboxes (usability).
Allows the Controller method to receive a super tidy array of ints, which ONLY contains the ints that have been selected - and not a whole other pile of items which were unselected or containing false/null/blank/0 etc.
Retains the checkbox's checked state when the page reloads containing the form, i.e. the user's selection is retained.
No random/stray type=hidden input fields created from the default ASP.Net MVC Html.CheckBox helper - I know it does those for a good reason, but in this instance, I don't require them as I only want to know about which IDs have been selected and for those to be in a single, tidy int[].
No masses of additional server side bloated classes, helpers and other happy mess required to achieve such a simple thing.
I would recommend this approach for anyone wanting the cleanest / bloat-free solution for a dynamic checkbox list where you need the IDs and you just want to get down to business!
The problem is that when you are rendering your list of checkboxes, you aren't setting any of them as selected. You will need to set your int[] Features in ViewData, and then in your foreach loop, check to see if the ID of that Feature is in the array in ViewData.
something like:
<%=Html.CheckBox("Features",
((int[])ViewData["SelectedFeatures"]).Contains(Feature.PropertyFeatureID),
new { #id = Feature.PropertyFeatureID, #value = Feature.PropertyFeatureID })%
although I didn't test it, so it might not be 100%.
I have a drop down in a MVC View, which is some thing like this:
Html.DropDownList(id, Range(0,10)
.Select(x => new SelectListItem {Text = x, Value = x}))
In the view itself, I need the selected value of this drop down. I know that I can access that in a JavaScript, but I am looking for a way to get it in the view itself from the drop down properties or something like that.
How can I access it? I tried to figure out some thing from intellisense but nothing relavant showed up, help is much appreciated.
Edit: I want the value after a few lines after the declaration of the drop down, I know that I can access it from JavaScript and by posting the form, Is there noway to access it on the view itself ?
Edit2: If its not possible to access it in view, please explain the reason, I am more interested in knowing it.
Thanks.
After reading at your question, it sounds like you want to have the drop down list supply a value for a lower section of the same page.
First and foremost, you will need to place the DropDownList within a form construct, as in:
<% using (Html.BeginForm("ProcessValue", "ThisPage")) { %>
<%= Html.DropDownList("DropID", Range(0, 10).Select(a=>new SelectListItem { Text = x, Value = x }) %>
<input type=submit value="Submit" />
<% } %>
You need to set up a few things ahead of time:
You have to have a submit button, or a similar construct, in order to retrieve the value of the DropID variable.
You need to set up an controller method that will handle the processing of the value, then redirect back to the original page with the selected value in the page's ViewData.
Finally, you need to set up the view so that the post-processing section will only display if you have a valid value in the DropID variable.
It's not as simple as just placing a DropDownList in a view and then using that value later on in the page. You have to get the controller involved to manage the data transport and you have to set up the single view to handle multiple states (ie. before the value is selected and after the selection takes place).
To get the selected value you could use either javascript or a controller action to which the form containing the select box is submitted.
The selected value will be in the FormCollection or QueryString collection with the name of the DropDown's ID in the controller action that receives the form submission from this view. You can either submit the values with a classic POST or GET or via AJAX, but you have to wire up a server-side action that processes that input.
There is a SelectList class as well wich allows you to define wich item will be selected.. and knowing that - you will know selected value..
Also.. if no value is selected explicitly, dropdowns tend to select the first item in the list.