I have multiselect jquery plagin (Choosen) and when I use it in 'Multiple Select' mode I expect in controller next values:
posted string = 'value1,value2...'
really have
posted string = 'value2'
only if I reffer directly to FormCollection I'll get expected values as below:
[HttpPost]
public ActionResult TagSearech(/*string tagSelect*/FormCollection c)
{
// only one value here
// string[] names = tagSelect.Split(',');
// as expected: value1,....
string expectedValue = c['tagSelect'];
return View();
}
I cant understand what might cause this behavior.
EDIT
Here is View:
#using (Html.BeginForm("TagSearech", "Tag"))
{
#Html.DropDownList("tagSelect", Model, new { #class = "chzn-select", data_placeholder = "tag names", multiple = "" })
<input type="submit"/>
}
MVC will attempt to bind the input data on the URL into the model. I haven't seen how Chosen.js posts the data back to the server, but essentially its coming in in the wrong format, so MVC binds the first element it sees to the string Model.
The FormsCollection retrieves all of the data that was posted in the URL, which is why all of your selected values can be seen there.
Did you try changing the incoming model from string to string[], and see if all of the items are bound to the array?
Related
I'm trying to build an html helper for creating a list of checkboxes, which will have the check state persisted using sessions. It works for the most part, remembering check box states when you check and uncheck various boxes and click submit. However, if you have boxes checked and submitted, and you go back and clear the checkboxes and resubmit (when they are ALL cleared) - it seems to want to remember the last selections. Here is what I've written...
[HomeController]
public ActionResult Index()
{
TestViewModel tvm = new TestViewModel();
return View(tvm);
}
[HttpPost]
public ActionResult Index(TestViewModel viewModel)
{
viewModel.SessionCommit();
return View(viewModel);
}
[Index View]
#model TestApp.Models.TestViewModel
#{
ViewBag.Title = "Index";
}
#using (Html.BeginForm())
{
<p>Checkboxes:</p>
#Html.CheckedListFor(x => x.SelectedItems, Model.CheckItems, Model.SelectedItems)
<input type="submit" name="Submit form" />
}
[TestViewModel]
// Simulate the checklist data source
public Dictionary<int, string> CheckItems
{
get
{
return new Dictionary<int, string>()
{
{1, "Item 1"},
{2, "Item 2"},
{3, "Item 3"},
{4, "Item 4"}
};
}
}
// Holds the checked list selections
public int[] SelectedItems { get; set; }
// Contructor
public TestViewModel()
{
SelectedItems = GetSessionIntArray("seld", new int[0] );
}
// Save selections to session
public void SessionCommit()
{
System.Web.HttpContext.Current.Session["seld"] = SelectedItems;
}
// Helper to get an int array from session
int[] GetSessionIntArray(string sessionVar, int[] defaultValue)
{
if (System.Web.HttpContext.Current.Session == null || System.Web.HttpContext.Current.Session[sessionVar] == null)
return defaultValue;
return (int[])System.Web.HttpContext.Current.Session[sessionVar];
}
[The HTML helper]
public static MvcHtmlString CheckedList(this HtmlHelper htmlHelper, string PropertyName, Dictionary<int, string> ListItems, int[] SelectedItemArray)
{
StringBuilder result = new StringBuilder();
foreach(var item in ListItems)
{
result.Append(#"<label>");
var builder = new TagBuilder("input");
builder.Attributes["type"] = "checkbox";
builder.Attributes["name"] = PropertyName;
builder.Attributes["id"] = PropertyName;
builder.Attributes["value"] = item.Key.ToString();
builder.Attributes["data-val"] = item.Key.ToString();
if (SelectedItemArray.Contains(item.Key))
builder.Attributes["checked"] = "checked";
result.Append(builder.ToString(TagRenderMode.SelfClosing));
result.AppendLine(string.Format(" {0}</label>", item.Value));
}
return MvcHtmlString.Create(result.ToString());
}
public static MvcHtmlString CheckedListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, Dictionary<int, string> ListItems, int[] SelectedItemArray)
{
var name = ExpressionHelper.GetExpressionText(expression);
var metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
return CheckedList(htmlHelper, name, ListItems, SelectedItemArray);
}
I've read this SO question and I think this may be to do with the model binder not knowing when there are no checkboxes checked, but even though I've gone through that and various other posts - I'm no further forward.
In one post, I saw that a hidden field is often used in combination with the checkbox to pass the 'false' state of the checkbox, but I couldn't get it working with multiple checkboxes posting back to a single property.
Can anyone shed light on this?
EDITED : to include the demonstration project I've highlighted in this post. Hopefully this will help someone to help me!
Your main issue, and the reason why the previous selections are being 'remembered' when you un-check all items is that you have a constructor in your model that calls GetSessionIntArray() which gets the values you stored last time you submitted the form. The DefaultModelBinder works by first initializing your model (including calling its default constructor) and then setting the values of its properties based the form values. In the following scenario
Step 1: Navigate to the Index() method
Assuming its the first call and no items have been added to Session, then the value of SelectedItems returned by GetSessionIntArray() is int[0], which does not match any values in CheckItems, so no checkboxes are checked.
Step 2: Check the first 2 checkboxes and submit.
The DefaultModelBinder initializes a new instance of TestViewModel and calls the constructor. The value of SelectedItems is again int[0] (nothing has been added to Session yet). The form values are then read and the value of SelectedItems is now int[1, 2] (the values of the checked checkboxes). The code inside the method is called and int[1, 2] is added to Session before returning the view.
Step 3: Un-check all checkboxes and submit again.
Your model is again initialized, but this time the constructor reads the values from Session and the value of SelectedItems is int[1,2]. The DefaultModelBinder reads the form values for SelectedItems, but there are none (un-checked checkboxes do not submit a value) so there is nothing to set and the value of SelectedItems remains int[1,2]. You then return the view and your helper checks the first 2 checkboxes based on the value of SelectedItems
You could solve this by removing the constructor from the model and modifying the code in the extension method to test for null
if (SelectedItemArray != null && SelectedItemArray.Contains(item.Key))
{
....
However there are other issues with you implementation, including
Your generating duplicate id attributes for each checkbox (your use of builder.Attributes["id"] = PropertyName;) which is invalid html.
builder.Attributes["data-val"] = item.Key.ToString(); makes no sense (it generates data-val="1", data-val="1" etc). Assuming you want attributes for unobtrusive client side validation, then the attributes would be data-val="true" data-val-required="The SelectedItems field is required.". But then you would need a associated placeholder for the error message (as generated by #Html.ValidationMessageFor() and the name attribute of each checkbox would need to be distinct (i.e. using indexers - name="[0].SelectedItems" etc).
Your using the value of the property for binding, but the correct approach (as all the built in extension method use) is to first get the value from ModelState, then from the ViewDataDictionary and finally if no values are found, then the actual model property.
You never use the value of var metadata = ModelMetadata..... although you should be (so that you can remove the last parameter (int[] SelectedItemArray) from the method, which is in effect just repeating the value of expression.
Side note: The use of a hidden field is not applicable in your case. The CheckboxFor() method generates the additional hidden input because the method binds to a bool property, and it ensures a value is always submitted.
My recommendation would be to use a package such as MvcCheckBoxList (I have not tried that one myself as I have my own extension method), at least until you spend some time studying the MVC source code to better understand how to create HtmlHelper extension methods (apologies if that sounds harsh).
#Html.Partial("~/Areas/WO/Views/PartialContent/_FirstPage.cshtml", new ViewDataDictionary { { "WOID", WOID } })
In my Page i am accessing Partial view in the above way.
I need to pass WOID(view data dictionary) value from query string, For that i am using following Code
#{
var desc = Html.ViewContext.HttpContext.Request.QueryString.Get("ID");
Uri referrer = HttpContext.Current.Request.UrlReferrer;
string[] query = referrer.Query.Split('=');
int WOID = Convert.ToInt32(query[1]);
}
But the issue is this code is working in all browsers except I.E. i Need to Solve this problem.
Please help me
Instead of this you can have this value as part of you model and use that.That is the standard and recommeded way .
In your action method you can have these as parameter.Your query string value will get bind to this parameter
public ActionResult ActionMethod(int ID)
{
Model.WOID = WOID;
// Other logic
return View(Model)
}
Next step you can add this as a property to your view model or add it to ViewData dictionary and then access it in your partial view.
I want to render the same view after a successful action (rather than use RedirectToAction), but I need to modify the model data that is rendered to that view. The following is a contrived example that demonstrates two methods that that do not work:
[AcceptVerbs("POST")]
public ActionResult EditProduct(int id, [Bind(Include="UnitPrice, ProductName")]Product product) {
NORTHWNDEntities entities = new NORTHWNDEntities();
if (ModelState.IsValid) {
var dbProduct = entities.ProductSet.First(p => p.ProductID == id);
dbProduct.ProductName = product.ProductName;
dbProduct.UnitPrice = product.UnitPrice;
entities.SaveChanges();
}
/* Neither of these work */
product.ProductName = "This has no effect";
ViewData["ProductName"] = "This has no effect either";
return View(product);
}
Does anyone know what the correct method is for accomplishing this?
After researching this further, I have an explanation why the following code has no effect in the Action:
product.ProductName = "This has no effect";
ViewData["ProductName"] = "This has no effect either";
My View uses HTML Helpers:
<% Html.EditorFor(x => x.ProductName);
HTML Helpers uses the following order precedence when attempting lookup of the key:
ViewData.ModelState dictionary entry
Model property (if a strongly typed view. This property is a shortcut to View.ViewData.Model)
ViewData dictionary entry
For HTTP Post Actions, ModelState is always populated, so modifying the Model (product.ProductName) or ViewData directly (ViewData["ProductName"]) has no effect.
If you do need to modify ModelState directly, the syntax to do so is:
ModelState.SetModelValue("ProductName", new ValueProviderResult("Your new value", "", CultureInfo.InvariantCulture));
Or, to clear the ModelState value:
ModelState.SetModelValue("ProductName", null);
You can create an extension method to simplify the syntax:
public static class ModelStateDictionaryExtensions {
public static void SetModelValue(this ModelStateDictionary modelState, string key, object rawValue) {
modelState.SetModelValue(key, new ValueProviderResult(rawValue, String.Empty, CultureInfo.InvariantCulture));
}
}
Then you can simply write:
ModelState.SetModelValue("ProductName", "Your new value");
For more details, see Consumption of Data in MVC2 Views.
The values are stored in ModelState.
This should do what you want:
ModelState.SetModelValue("ProductName", "The new value");
I wouldn't suggest doing that though... the correct method would be to follow the PRG (Post/Redirect/Get) pattern.
HTHs,
Charles
EDIT: Updated to reflect the better was of setting the ModelState value as found by #Gary
This will trigger the model to re-evaluate under simple conditions:
ModelState.Clear();
model.Property = "new value";
TryValidateModel(model);
Perform ModelState.Clear() before you change the model.
...
ModelState.Clear()
dbProduct.ProductName = product.ProductName;
dbProduct.UnitPrice = product.UnitPrice;
...
I have this
<%=Model.StartDate%>
<%=Html.Hidden("StartDate", Model.StartDate)%>
it outputs:
2010-05-11 11:00:00 +01:00
<input type="hidden" value="2010-03-17 11:00:00 +01:00" name="StartDate" id="StartDate">
What the...
It's a paging mechanism so the hidden value was valid on the first page and I've been able to move forward to the next page. But since the values won't update properly it ends there.
What do I need to do?
Using firefox.
Update - more code
using (Html.BeginForm("Program", "Activities", null, FormMethod.Get, new { #name = "ProgramForm", id = "ProgramForm" }))
{
.
viewModel.StartDate = pagingService.StartDate;
return View(viewModel);
Update - complete action
[Authorize]
public ActionResult Program(string[] submit)
{
var viewModel = new ActivityProgramViewModel { UserID = LoggedInUser.UserID };
viewModel.Fresh = true;
TryUpdateModel(viewModel);
var pagingService = new OccurencePagingService(LoggedInUser.AllActivities.Where(a => a.StartTime != null));
if (!viewModel.Fresh)
{
pagingService.StartDate = ((DateTimeOffset)viewModel.StartDate);
pagingService.EndDate = ((DateTimeOffset)viewModel.EndDate);
}
if (submit != null)
if (submit.Contains("MoveBack"))
pagingService.MoveBack();
else if (submit.Contains("MoveForward"))
pagingService.MoveForward();
ViewData.Model = viewModel;
viewModel.Occurrences = pagingService.GetOccurences();
viewModel.Fresh = false;
viewModel.HasLess = pagingService.HasLess;
viewModel.HasMore = pagingService.HasMore;
viewModel.StartDate = pagingService.StartDate;
viewModel.EndDate = pagingService.EndDate;
return View();
}
First one uses Model object, second one uses existing ModelState. Look at ModelState values before generating view. It propably holds value for this field. Html helpers priveded by MVC use ModelState to generate form fields. It helps in recreating values after post back.
To get rid of this kind of problems, use POST-REDIRECT-GET pattern or just pass query parameters through GET.
I think the <%=Html.Hidden("StartDate", Model.StartDate)%> is out of place here.
Html Helpers try to keep data in the UI like they where entered by examining the post/route data. Please dont ask me how someone would ever enter data in a hidden field.
You want something different: You want to set the data to Model.StartDate and dont care what is in the post/route.
I would use <input value="<%=Model.StartDate%>" name="StartDate" /> .
What is a good way to persist querystring values in asp.net mvc?
If I have a url:
/questions?page=2&sort=newest&items=50&showcomments=1&search=abcd
On paging links I want to keep those querystring values in all the links so they persist when the user clicks on the "next page" for example (in this case the page value would change, but the rest would stay the same)
I can think of 2 ways to do this:
Request.Querystring in the View and add the values to the links
Pass each querystring value from the Controller back into the View using ViewData
Is one better than the other? Are those the only options or is there a better way to do this?
i use a extension method for that:
public static string RouteLinkWithExtraValues(
this HtmlHelper htmlHelper,
string name,
object values)
{
var routeValues = new RouteValueDictionary(htmlHelper.ViewContext.RouteData.Values);
var extraValues = new RouteValueDictionary(values);
foreach (var val in extraValues)
{
if (!routeValues.ContainsKey(val.Key))
routeValues.Add(val.Key, val.Value);
else
routeValues[val.Key] = val.Value;
}
foreach (string key in htmlHelper.ViewContext.HttpContext.Request.Form)
{
routeValues[key] = htmlHelper.ViewContext.HttpContext.Request.Form[key];
}
foreach (string key in htmlHelper.ViewContext.HttpContext.Request.QueryString)
{
if (!routeValues.ContainsKey(key) && htmlHelper.ViewContext.HttpContext.Request.QueryString[key] != "")
routeValues[key] = htmlHelper.ViewContext.HttpContext.Request.QueryString[key];
}
var urlHelper = new UrlHelper(htmlHelper.ViewContext.RequestContext);
return string.Format("{1}", urlHelper.RouteUrl(routeValues), name);
}
I would process the QueryString in the view (your option #1), instead of passing it in from the controller. This approach makes the view more self-contained, allowing you to convert it into a view control and re-use it across different views.
Note: Accessing the QueryString directly in the view may seem like a violation of the design principle of separating the Model and View, but in reality this data is a navigational concern which is related to the view, not really part of the model.
I would just keep the values in the Session that way the paging links only need to have;
/questions?page=2
/questions?page=3
The one reason why I would not us the QueryString is because I don't want the user to see the values that I am passing to the program. It makes it way too easy for them to go into the address bar and start changing the values to 'see what happens'. With this code all they could do is change the page number.
Here's how I done it in Asp.Net Core, first assign the query string parameters to ViewBags in your controller:
[HttpGet("/[controller]/[action]/{categoryId?}/{contractTypeId?}/{locationId?}")]
public IActionResult Index(Guid categoryId, int contractTypeId, Guid locationId)
{
ViewBag.CategoryId = categoryId;
ViewBag.ContractTypeId = contractTypeId;
ViewBag.LocationId = locationId;
...
}
Then pass the values to your links like so:
<a asp-action="Index" asp-controller="Jobs"
asp-route-categoryId="#teachingCategory.Id"
asp-route-contractTypeId="#ViewBag.ContractTypeId"
asp-route-locationId="#ViewBag.LocationId">
#teachingCategory.Description (#teachingCategory.Rank)
</a>
<a asp-action="Index" asp-controller="Jobs"
asp-route-categoryId="#ViewBag.CategoryId"
asp-route-contractTypeId="#typeOfEmployment.Id"
asp-route-locationId="#ViewBag.LocationId">
#typeOfEmployment.Name
</a>
<a asp-action="Index" asp-controller="Jobs"
asp-route-categoryId="#ViewBag.CategoryId"
asp-route-contractTypeId="#ViewBag.ContractTypeId"
asp-route-locationId="#item.Id">
#item.Id
</a>
Note that every link keep its own actual value and pass the rest of the route values through what we passed to ViewBag.