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How to prevent controller from changing the View

I'm new to MVC, and currently I'm trying to create a function for my form that exports it values to PDF. I managed to do that using input with submit type that calls the controller.
My problem is when I want to keep the values in the form (because I want to create another button that will send the form as e-mail), but the form resets after clicking on the button.
I tried creating void function instead of action result, but after calling, the browser tries to redirect to another page with controller names as URL.
I also tried to change the input type from submit to button, but after changing it, it won't call the controller on click.
So there is my question, how to call the controller without causing the form to reset its values.
Here is index.cshtml that calls the controller
<div class="row clearfix">
<div class="input-group">
<input id="pdfBtn" value="Export to pdf" type="submit" formaction="#Url.Action("pdfExport")" />
</div>
</div>
Here is the controller
[HttpPost]
public ActionResult pdfExport([Bind(Include = "formId,formType,additionalTypeInfo,nameSurname,description,Attachment")] FormModel model)
{
if (ModelState.IsValid)
{
var pdf = new FormToPdf(model);
}
return RedirectToAction("Index");
}

You can try to return the model to Index action like this:
[HttpPost]
public ActionResult pdfExport([Bind(Include = "formId,formType,additionalTypeInfo,nameSurname,description,Attachment")] FormModel [HttpPost]
public ActionResult pdfExport([Bind(Include = "formId,formType,additionalTypeInfo,nameSurname,description,Attachment")] FormModel model)
{
if (ModelState.IsValid)
{
var pdf = new FormToPdf(model);
}
return RedirectToAction("Index");
})
{
if (ModelState.IsValid)
{
var pdf = new FormToPdf(model);
}
return RedirectToAction("Index",model);
}
Or you can use ajax to pass data when button click,so that the page will not be refreshed:
<input id="pdfBtn" value="Export to pdf" type="button" onclick="pdfExport()"/>
js:
function pdfExport() {
$.ajax({
type: "POST",
url: "pdfExport",
data: Data,
success: function (data) {
}
});
}

You are doing Redirection in your server side code.
Do an AJAX call to your MVC controller (better if it is Web API controller) and from controller return HTTP OK / HTTP Accepted. While doing AJAX call using JavaScript/jQuery on button click, prevent the default behaviour (submit the form) of the button like in this way:
function onButtonClickPdfExportToServerUsingAjax(e){
e.PreventDefault();
// AJAX call
}
After receiving successful AJAX call response, proceed with whatever you want to do next.

Send Selected DropDownList value to HomeController ActionResult

Hi I have a drop down list that is filled in from comma delimited values in the config. This works fine.
What I am trying to do is to send the selected value on button click to a ActionResult in the HomeController.
I created a Model, which is taking a string. When I hit the button I get error:
The view 'TestAction' or its master was not found or no view engine supports the searched locations.
This is what my Controller looks like:
[HttpPost]
[ActionName("TestAction")]
public ActionResult TestAction(SQL_Blocks_App.Models.DropdownList SelectedValue)
{
//System.Diagnostics.Debug.WriteLine(SelectedValue);
return View();
}
This is what my model looks like:
public class DropdownList
{
//
// GET: /DropdownList/
[Display(Name = "Servers")]
public string SelectedValue{ get; set; }
}
and this is what my Index View looks like:
<form id="SelectedValue" action="/Home/TestAction" method="post" style="margin: 0">
<div class="col-lg-5">
#{
ViewBag.Title = "Index";
}
#Html.DropDownList("YourElementName", (IEnumerable<SelectListItem>)ViewBag.DropdownVals, "--Choose Your Value--", new
{
//size = "5",
style = "width: 600px"
})
</div>
<div class="col-lg-5">
<input type="submit" value="Run Query" />
<input id="Button2" type="button" value="Clear" onclick="window.location.reload()" />
</div>
</form>
I want to clarify. My end goal is to use the selected value in a SQL query in the ActionResult and return the results back to the index so I can fill them in a table. ( You don't have to show me how to do the SQL part for now I just would like to see the selected value at least printed in the output.)

Redirect to index action, and pass the parameters along
[HttpPost]
[ActionName("TestAction")]
public ActionResult TestAction(SQL_Blocks_App.Models.DropdownList _selectedValue)
{
//System.Diagnostics.Debug.WriteLine(SelectedValue);
return RedirectToAction("Index", "[Controller]", new {#_selectedValue = _selectedValue });
}
and then your Index method should accept the parameter.
[HttpGet]
public ActionResult Index(SQL_Blocks_App.Models.DropdownList _selectedValue)
{
//use _selectedValue
}
I would recommend using another method other than your index, or make Dropdownlist nullable/set a default for it.

The default framework behavior of return View() is to return a view with the same name as the currently-executing action. Which is TestAction. The error is telling you that no such view was found.
You have a couple of options. You can either create the view, or you can return something else. For example, if you want to redirect back to the Index then you can return a redirect result:
return RedirectToAction("Index");
You could also specify the Index view in the response:
return View("Index");
However, keep in mind that the URL will still be for TestAction and not for Index, which could result in unexpected changes to behavior if you're not aware of this.
Edit: Based on comments on this answer, it sounds like what you actually want is to build a pair of actions which generally operate on the same view. This isn't particularly common for an index view, but is very common for edit views. The only difference is semantics, structurally the concept works anywhere.
Consider two actions:
public ActionResult Index()
{
// just show the page
return View();
}
[HttpPost]
public ActionResult Index(SQL_Blocks_App.Models.DropdownList SelectedValue)
{
// receive data from the page
// perform some operation
// and show the page again
return View();
}
Requests between these two actions would differ only by the HTTP verb (GET or POST), not by the action name on the URL. That name would always be "Index". But when the form on the index view is submitted via POST and has a "SelectedValue", the second action is invoked instead of the first.
In that second action you would perform your database interaction, gather whatever data you needed, and if necessary include a model or some additional data in the response.

You TestAction method is returning to a View. Make sure View TestAction.cshtml exists and is in the Home folder.

ViewDataDictionary vs anonymous object in ASP.net MVC 5

I am a beginner and I am going through some tutorials in my MVC. So, I came across two scenarios.
Scenario 1.
I had to pass some data to my view on post and then send that data as hidden field. Here is the code.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult ForgotPassword(ForgotPasswordMV viewModel)
{
if (ModelState.IsValid)
{
return RedirectToAction("VerifyToken", new { emailId = viewModel.EmailId });
}
^^ USING ANONYMOUS OBJECTS
return View();
}
public ActionResult VerifyToken(string emailId = null)
{
VerifyTokenMV viewModel = new VerifyTokenMV
{
EmailId = emailId
};
return View(viewModel);
}
VerifyToken View
#using (#Html.BeginForm("VerifyToken", "Security"))
{
#Html.HiddenFor(m => m.EmailId)
<button class="btn btn-primary">Continue</button>
}
Works Perfectly fine. I am able to receive values of EmailId. So far so good.
Scenario 2.
Needed to open a partial view from Main view, here is the snippet.
Main cshtml file
<div class="abc">
#Html.Partial("../Widget/Customize", Model.Unit, new ViewDataDictionary() { { "ElementName", "UnitWidget" } })
</div>
partial cshtml file
#{
string custWidgetElementName = ViewBag.ElementName;
}
// some html code below
Observation:
In scenario 2 why have I used ViewDataDictionary. Although both example works perfectly fine. But is there any reason that I had to use ViewDataDictionary. In scenraio 1 can we use ViewDataDictionary? If Yes, then which one is optimum solution.
Question: When I need to pass values shall I use new {key : value} or use ViewDataDictionary or there is no corelation? Instead of ViewDataDictionary can I use anonymous object in Senario 2

Your two scenarios are totally different. They are not doing the same thing.
In scenario 1 when using this line:
return RedirectToAction("VerifyToken", new { emailId = viewModel.EmailId });
A new URL is genrated and sent back to the client (the browser) with HTTP Code 301 or 302. When received the browser will re-contact your application wiht the received URL. With that URL, your application will execute the associated action. In your case, the client's browser will call VerifyToken action with the emailId parameter setted when you call RedirectionToAction into ForgotPassword action. So using RedirectionToAction method is just telling that method to generate a new URL with parameter defined in the anonymous type.
In scenario 2 is completely different to scenario 1. With this line:
#Html.Partial("../Widget/Customize", Model.Unit, new ViewDataDictionary() { { "ElementName", "UnitWidget" } })
You're telling your view to inject the partial view which path is ../Widget/Customize. Because that partial view the strongly typed, you passed Model.Unit as an second parameter. You use also a third parameter new ViewDataDictionary() { { "ElementName", "UnitWidget" } } because your partial seems to internally need to access to the dynamic property ViewBag or dictionary property ViewData of your view.
Conclusion:
In scenario 1 you are just telling the client's browser to go to the new URL you have generated after requesting ForgetPassword URL. We just call that a rediretion.
In scenario 2, you're just rendering a partial view into a view. The client's broswer doesn't know anything what's going on with partial views they don't know if they exist.

How to use RouteConfig to append a page URL

I am struggling to get my code work, but I think I've read enough to suggest this is the correct way to approach this.
On my intranet, I'd like the user to type in a single word to search into a textbox, and check a checkbox. When the new page loads, I'd like the URL rewritting services of ASP.NET MVC to kick in and change a value from
mysite.com/?id=blah&isChecked=true
to
mysite.com/home/index/blah/true
My code isn't working in the sense of it gives no error, but doesn't do what I am explaining. So, I've removed the check box to just focus on the textbox.
My only route is
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{MyType}",
defaults: new { controller = "Home", action = "Index", MyType = UrlParameter.Optional }
);
My Controller
public ActionResult Index()
{
ViewBag.Message = "Modify this";
return View();
}
[HttpGet]
public ActionResult Index(string MyType)
{
ViewBag.Message = "..." + MyType;
return View();
}
and my View has
#using (Html.BeginForm("Index", "Home",FormMethod.Get))
{
<input name="MyType" /><br />
<input type="submit" />
}
#Html.ActionLink("Click me", "Index", new { #MyType = "Blah" }) //renders correctly
The problem is, it shows the querystring still in the address bar
mysite.com/?MyType=MySearchValue
instead of
mysite.com/Home/Index/MySearchValue

You can't do this purely with routing because the browser will always send form values as query string parameters when they are part of a GET request. Once the request has been sent to the server, the MVC framework can't do anything about the URL that was used.
This leaves you with only one real option (assuming you don't want to send a custom request using JavaScript), which is to explicitly redirect to the desired URL (meaning you will always have two requests when this form is submitted).
The simplest way of doing this is simply in the controller (rather, in a separate controller to ensure that there is no conflict in method signatures):
public class FormController : Controller
{
public ActionResult Index(string MyType)
{
return RedirectToAction("Index", "MyProperController", new { MyType });
}
}
If you direct your form to this controller action, MVC will then use the routing engine to generate the proper URL for the real action and redirect the browser accordingly.
You could do this from the same controller action but it would involve inspecting the request URL to check whether a query string was used or not and redirecting back to the same action, which is a little odd.

MVC 3 - How do you return a Display Template from an action method?

I have a view that displays a list of comments. It does this via the DisplayTemplate. All I have to do is something like #Html.DisplayFor(x => x.BlogPost.PostComments) and all the comments render appropriately.
There is a form at the bottom of the page to add a new comment. This page utilizes progressive enhancement. So if javascript is disabled then the form submits like normal, adds the comment to the database, then redirects to the action that renders the blog post. However, if javascript is available then jQuery hijacks the form's submit and makes the post via ajax. Well because the comment markup is in a display template, I don't know how to return it from the action method so that jQuery can drop it on the page.
I know how to do this with partial views. I would just have the action method return the right partial view and jquery would append the response to the comment container on the page.
Before I go chopping out my display template in favor of a partial view, is there a straight forward way that I'm missing to send back a display template from the controller?
Here is my action method:
public ActionResult AddComment(PostComment postComment)
{
postComment.PostedDate = DateTime.Now;
postCommentRepo.AddPostComment(postComment);
postCommentRepo.SaveChanges();
if (Request.IsAjaxRequest())
return ???????
else
return RedirectToAction("BlogPost", new { Id = postComment.BlogPostID });
}
When the page loads it doesn't need to worry about it because it uses the templates in the standard way:
<div class="comments">
#Html.DisplayFor(x => x.BlogPost.BlogPostComments)
</div>
I just want to know how I might send a single comment that utilizes the display template back to jQuery.

You may try returning the partial HTML representing the newly posted comment:
if (Request.IsAjaxRequest())
{
return PartialView(
"~/Views/Shared/DisplayTemplates/Comment.cshtml",
postComment
);
}
and on the client side append this comment to the comments container:
$.post('#Url.Action("AddComment")', { ... }, function (result) {
$('#comments').append(result);
// or $('#comments').prepend(result); if you want it to appear on top
});

Does this question give you what you are looking for? Seems to indicate that you can call a HTML helper from an action.

Create a partial view /Shared/DisplayTemplate.cshtml with the following razor code:
#Html.DisplayFor(m => Model)
Then in your controller (or preferably in a base controller class) add a method along these lines:
protected PartialViewResult PartialViewFor(object model)
{
return PartialView("DisplayTemplate",model);
}
In the OP's case then:
public ActionResult AddComment(PostComment postComment)
{
postComment.PostedDate = DateTime.Now;
postCommentRepo.AddPostComment(postComment);
postCommentRepo.SaveChanges();
if (Request.IsAjaxRequest())
return PartialViewFor(postComment);
else
return RedirectToAction("BlogPost", new { Id = postComment.BlogPostID });
}