I'm fixing bugs for some application, and I need help understanding the following lines of code:
Here,
View:
#Html.RenderControlText("WFD_CONSENT")
Controller:
public static MvcHtmlString RenderControlText(this HtmlHelper htmlHelper, string controlType)
{
return htmlHelper.Action("ControlText", new { controlType = controlType });
}
The parameter controlType = "WFD_CONSENT" here.
I can't get what the function htmlhelper.Action() is doing here.
Logically, this function RenderControlText() should be fetching some data from somewhere, but it doesn't look like it. I'm at a dead end here.
This method RenderControlText() should fetch some text which I've saved somewhere, and display it.
EDIT: The Action() method has the follwing parameters: action-name and object routevalues?
What's the second part: new { controlType = controlType } ? What does this routevalues do??
I can't get what the function htmlhelper.Action() is doing here.
Take a look at the following blog post from Phil Haack where he explains child actions in details.
The Html.Action helper basically executes a child action. A child action is a standard controller action except that it could be rendered in parallel with the execution of the main request.
Html.Action("SomeAction", "SomeController") means that the SomeAction will be executed on SomeController and the result of execution of this action rendered to the output.
In contrast: Html.Action("SomePartial") means that the SomePartial will directly be rendered to the output without the execution of any child controller and action.
But in both cases all the processing happens in a single client request. It's just that you have the primary controller action that is executed and rendered a view and inside this view you used the Html.Action helper to instantiate a child controller and action (which could return for example a partial view) and the result of the execution of this view is directly inserted into the output.
Related
In using Razor pages, it is simple to use partial using #Html.Partial(..).
However, when a drop down changes, I want to refresh part of the view - the part rendered by the partial view.
I have searched lots, and found answers such as: https://github.com/aspnet/Razor/issues/2073 where they say partials are meant for code behind.
Is there a reasonable workaround such that I can re-render a subset of the view which is defined in a partial view? What is the best practice way of achieving this?
Yes,
Have an action method that can be called to reload just the partial view:
public ActionResult Reload()
{
return PartialView("NameOfPartialView");
}
Get it from the client (I'll use jQuery):
$.ajax({
type: "post",
url: "Reload",
data: {},
success: function(d) {
//d is the HTML content returned from the Action Method
$("#parentelementaroundinnerdata").html(d);
}
});
Returning the partial view from the action method returns an HTML string, and that can be injected into the page using a parent element to replace its contents with the update. That means when rendering the original, have the setup as the following:
<div id="parentelementaroundinnerdata">
#Html.Partial("NameOfPartialView")
</div>
You can use the same partial from an AJAX request and for loading an initial result - sometimes you have to be careful within the partial on what is going on because of that though...
I have a PartialView called TopPanel. This Panel is responsible for displaying error messages generated on any page in my application. To handle this, when any exception occurs on a page, I have it call an "ErrorHandler" action in the TopPanel controller. ErrorHandler updates the ViewBag with the error message and calls the Index action which just returns the partial view(for now, since im testing. I will have it call the Main Controllers Index Action later to display the whole page). My understanding is that calling the Index action will reload the view and the ErrorDiv that I have on TopPanels PartilaView will be able to display the new error message in ViewBag. However, nothing gets displayed and I'm not sure why.
Heres some code -
The ErrorHandler Action -
public ActionResult ErrorHandler(string message)
{
ViewBag.ErrorMsg = message;
return RedirectToAction("Index");
}
I've checked in the debugger, "message" does have a valid value. And ViewBag.ErrorMsg does get populated as well.
Index Action of TopPanel -
public ActionResult Index()
{
return PartialView();
}
TopPanels PartialView contains this lone which displays the error -
<div id="errorMsgBox">#ViewBag.ErrorMsg</div>
Can anyone point out what the issue is?
RedirectToAction is like a browser redirect. It actually sends the redirect code to the browser and the action name is the new URL to request. As such you're actually sending a new request to the server for a new page, which will have its own ViewBag.
Instead of RedirectToAction you might just want to return the View and specify the PartialView name.
Since you are doing a redirect, you are actually going to end up in a completely separate Request/Response which has no knowledge of the previous ViewBag property value.
I'm moving my WebForms project to MVC and having a hard time designing things.
The basic display of my app is in _Layout. The page is divided into 4 parts(say Part A,B,C and D), with 3(A,B,C) just containing html and one(D) is dynamic. I had used #RenderBody to bring in the content of Part D. However, now the other parts are changing and I need separate controllers for these parts. What is the best way to get their contents to be displayed into _Layout?
#Html.RenderPartial / #Html.Partial / #Html.RenderAction / #Html.Action ?
I'm currently trying to replace Part C by using -
#Html.Action("Index", "CController")
However, this is not working.
In Index.cshtml for CController, I've the Layout = null, initially it was set to point to _Layout.cshtml, but I read here that this created issues.
After putting the C Part in CControllers view, it does not event display the basic _Layout page that it displayed earlier.
Here's the Index.cshtml of CController -
<div id="noteContainerDiv">
Here goes all the data to display
</div>
And Here's the code for CController.cs -
public class CController : Controller
{
public ActionResult Index()
{
return PartialView();
}
}
Can anyone suggest the right way to design this?
What you could do is have a view model for your subview (the one you call D) and pass in this view model from your layout view.
I.e. by doing something like this in your _Layout:
#Html.Partial("_SubviewD", Model.SubviewDModel)
Then obviously in your controllers you need to initialize this subview model and include it in your model (or alternatively, in the ViewBag--apologies for suggested being evil!) You could even find ways to do this without changing all your controllers (for example through a base Controller class and overriding OnActionExecuted).
There are many ways you could do this. But I would stick to your initial approach.
Have your CController Index action return a PartialViewResult instead of a full result.
You don't set the layout for partial views. So in your CController index action you'll have something like this:
var model = ....
return this.PartialView("NameOfYourPartialView", yourModel);
And when you call
#Html.Action("Index", "CController")
Everything should be OK, cool?
I have defined an action on my controller which accepts an integer and returns a string value:
public string SqlQuery(int listItemId)
{
return _sqlListSharePointList.GetSqlQueryFromCache(listItemId);
}
How could I call this action from my view? also what other options do I have apart from AJAX?
I tried the below but didn't work:
$.get('/SqlReportList/SqlQuery', 1, function (data) {
alert(data);
});
the "SqlReportList" is the name of my controller.
I also tried the below code:
$.get('/SqlReportList/SqlQuery/1', function (data) {
alert(data);
});
But it threw an exception on production that the listItemId is null.
Should I decorate my Action differently?
I also tried accessing it via fully qualified name but same error:
http://localhost:4574/SqlReportList/SqlQuery/1
Thanks,
If you do not want to use ajax (which is recommended) then only way to call the method is thru page refresh, only that way you are hitting your server side (controller) again from the view.
$.get('/SqlReportList/SqlQuery', { "listItemId": listItemId }, function (data) {
$('#tbSqlQuery').text(data); }
);
Is the parameter known at the time of rendering the surrounding page?
If so (and I've understood your question correctly) then you can use Html.RenderAction. See http://haacked.com/archive/2009/11/17/aspnetmvc2-render-action.aspx
If not, then you can only really use AJAX or a full page reload. For getting the URL right for AJAX, you should be able to use Url.Action with some placeholder value.
The T4MVC project offers strongly-typed support for various things including action URLs, even supporting explicit placeholders for Javascript code. See section 2.2.2 of http://t4mvc.codeplex.com/documentation
I want to build a webapplication with a "Single Page Interface", using ASP.NET MVC.
I have searched if this was at least possible and I think the answer is: not by simple means (reading http://msdn.microsoft.com/en-us/magazine/cc507641.aspx#S2 second-last paragraph; that article is from May 2008, though).
I found other examples which implemented this by coding/hacking with jQuery. However, I'm looking for a clean solution, using standard .NET approaches, if possible.
What I want is precisely the same functionality when you create a new "MVC Web Application". However, instead of links to "/Home/About" which reloads the entire page, I want links to "#Home/About" which loads only the new part via AJAX.
The standard approach of calling templates (partial views) with Html.RenderPartial is exactly what I want, only then loading them in through AJAX-requests.
Of course, it might be that I can't use these templates that are rendered by the Master-page for some reason (maybe it's expecting to always be called in a certain context from a certain place or so). But maybe there's another clean solution for how to build your template-pages and fetching them from the Master-page.
Who has a nice solution for implementing such thing, a Single Page Interface?
PS: I'm developing in Visual Web Developer 2008 Express Edition with MVC 1.0 installed, in C#
[edit]
Below I read that working with the templates is possible and that jQuery looks indeed like inevitable, so I tested it.
The following code transforms regular links created by Html.ActionLink into anchor-links (with #) to contain history, and then fetch the page via AJAX and only injecting the html-part I'm interested in (i.e. the partial page inside div#partialView):
$("a").each(function() {
$(this).click(function() {
$("div#partialView").load($(this).attr("href") + " div#partialView");
location.hash = $(this).attr("href");
return false;
});
});
These links also allow for graceful degredation.
But what I have left now, is still fetching the whole page instead of only the partial page. Altering the controller didn't help; it still provided me html of the whole page, with all of these statements:
public ActionResult About()
{
return View();
return View("About");
return PartialView();
return PartialView("About");
}
How could I only return the content of the part I'm interested in (i.e. the contents of Home/About.aspx)?
What I'd like is POSTing a value with AJAX (e.g. "requesttype=ajax") so that my controller knows the page is fetched via AJAX and only returns the partial page; otherwise it will return the whole page (i.e. when you visit /Home/About instead of #Home/About).
Is a good practice to alter Global.asax.cs maybe, to create a new routing schema for AJAX-calls, which will only return partial pages? (I haven't looked into this much, yet.)
[edit2]
Robert Koritnik was right: I also needed an About.ascx page (UserControl) with only the small HTML-content of that page. The first line of About.aspx was linked with the Master-page via MasterPageFile="~/..../Site.master" which caused that all HTML was printed.
But to be able to execute the following in my controller:
public ActionResult About()
{
return Request.IsAjaxRequest() ? (ActionResult)PartialView() : View();
}
I needed to alter the way a PartialView (.ascx file) and a View (.aspx) file was found, otherwise both methods would return the same page (About.aspx, ultimately resulting in an infinite loop).
After putting the following in Global.asax.cs, the correct pages will be returned with PartialView() and View():
protected void Application_Start()
{
foreach (WebFormViewEngine engine in ViewEngines.Engines.Where(c => c is WebFormViewEngine))
{
/* Normal search order:
new string[] { "~/Views/{1}/{0}.aspx",
"~/Views/{1}/{0}.ascx",
"~/Views/Shared/{0}.aspx"
"~/Views/Shared/{0}.ascx"
};
*/
// PartialViews match with .ascx files
engine.PartialViewLocationFormats = new string[] { "~/Views/{1}/{0}.ascx", "~/Views/Shared/{0}.ascx" };
// Views match with .aspx files
engine.ViewLocationFormats = new string[] { "~/Views/{1}/{0}.aspx", "~/Views/Shared/{0}.aspx" };
}
RegisterRoutes(RouteTable.Routes);
}
Full view vs. Partial view
Seems like you've messed up something. If you create an About.aspx page with all the HTML needed to display the whole page it doesn't really matter if you say
return PartialView('About');
The view still returns all the HTML that's written in it.
You should create a separate About.ascx that will only have the content of the page itself without the header and other stuff that's part of the whole page.
Your original page About.aspx will have something like this in its content (to avoid repeating writing the same content twice):
<%= Html.RenderPartial("About") %>
And you can have two controller actions. One that returns a regular view and one that returns a partial view:
return View("About"); // returns About.aspx that holds the content of the About.ascx as well
return PartialView("About"); // only returns the partial About.ascx
Regarding routes in Global.asax
Instead of writing separate routes for Ajax calls you'd rather write an action filter that will work similar as AcceptVerbsAttribute action filter. This way your requests from the client would stay the same (and thus preventing the user from manually requesting wrong stuff), but depending on the request type the correct controller action will get executed.
Well, you can load Partial View through AJAX request. In example, I'll use jquery to make an ajax call.
These could be the action in controller (named HomeController):
public ActionResult About()
{
//Do some logic...
//AboutView is the name of your partial view
return View("AboutView");
}
JQuery ajax call to place the retured html in place you want:
var resultDiv = $('#contentDIV');
$.ajax({
type: "POST",
url: "/Home/About",
success: function(responseHTML) {
resultDiv.replaceWith(responseHTML);
}
});
[edit-question is updated]
It is possible to do exactly what you want. First controller action can give you back the partial view, so mine "AboutView" could have been something like this:
<table>
<tr>
<th>
Column1Header
</th>
<th>
Column2Header
</th>
</tr>
<tr>
<td>
...
</td>
<td>
...
</td>
</tr>
and this HTML is exactly what are you going to have in responseHTML on success handler in jquery ajax method.
Second, you can distinguish in controller action if the request is an ajax request:
public ActionResult About()
{
//partial AboutView is returned if request is ajax
if (Request.IsAjaxRequest())
return View("AboutView");
else //else it will be the default view (page) for this action: "About"
return View();
}
We've got a site that does exactly this, and you really want to use the jQuery route here--alot easier to implement in the long run. And you can easily make it gracefully degrade for users who don't have javascript enabled--like google.
it isn't all that clear what are you asking for, is it for a complete example or for some specific functionality? You should be able to do this without JQuery for simple scenarios, you can use the Ajax view helpers like the ActionLink method. Also, I don't really understand what is your issue with RenderPartial, but maybe you're looking for something like RenderAction from ASP.NET MVC Futures.
ASP.NET MVC 4 (now in beta) adds support for Single Page Applications in MVC.
http://www.asp.net/single-page-application
UPDATE:
...and they removed it from the MVC 4 RC
UPDATE:
...and it is back with the 2012 Fall update