I have latest Visual Studio 2019 16.5.4 Enterprise.
I've just created an ASP .Net Core 3.1 MVC application from a template (with default settings).
And I've added some JavaScript code to a Home Page's Index.cshtml:
#{
ViewData["Title"] = "Home Page";
}
<div class="text-center">
<h1 class="display-4">Welcome</h1>
<p>Learn about building Web apps with ASP.NET Core.</p>
</div>
#section Scripts {
<script>
function GetJSON_Simple() {
var resp = [];
return resp;
}
debugger;
var simpleData = GetJSON_Simple();
</script>
}
And I'm not able to debug JavaScript code (breakpoints inside GetJSON_Simple function body or on var simpleData = GetJSON_Simple() is never hit). I've tried both Chrome and MS Edge (Chromium).
According to this article (Debug JavaScript in dynamic files using Razor (ASP.NET) section):
Place the debugger; statement where you want to break: This causes the
dynamic script to stop execution and start debugging immediately while
it is being created.
P.S. I've already have Tools->Options->Debugging->General with turned on Enable JavaScript Debugging for ASP.NET (Chrome and IE) checkbox and of course I'm compiling in Debug.
My test project is attached
Howto debug JavaScript inside ASP .Net Core 3.1 MVC applications
(Razor view - *.cshtml)?
In fact, it is already a well-known issue. We can not debug the js code under Net Core razor page but only for code in separate js or ts files. See this link.
Solution
To solve it, I suggest you could create a new single js file called test.js and then reference it in razor page and then you can hit into js code when you debug it.
1) create a file called test.js and migrate your js code into it:
function GetJSON_Simple() {
var resp = [];
return resp;
}
debugger;
var simpleData = GetJSON_Simple();
2) change to use this in your cshtml file:
#{
ViewData["Title"] = "Home Page";
}
<div class="text-center">
<h1 class="display-4">Welcome</h1>
<p>Learn about building Web apps with ASP.NET Core.</p>
</div>
#section Scripts {
<script scr="xxx/test.js">
</script>
}
3) clean your project, then rebuild your project and debug it and you will hit into Js code.
Another way is to explicitly define the source mapping name for the script directly in your javascript code via a sourceURL comment.
<script>
...your script code
//# sourceURL=blah
</script>
The script in that block will show up in Chrome with the value you specified. You can then view and debug just like a normal .js file.
This is especially useful if you don't want to refactor an existing codebase that has embedded javascript in the cshtml files or really ANY codebase that has javascript loaded on the fly.
Live Example
You can actually see an example with the built-in javascript runner here. Just click 'Run Snippet' and then search for "blahblah" in your Page sources. You should see this:
alert("test");
//# sourceURL=blahblah
I access the HttpContext in a Blazor server-side view to manually log out. I added this line to Startup.cs: services.AddHttpContextAccessor(); and inject it in the view with #inject IHttpContextAccessor HttpContextAccessor.
I've got a log out button which tries to execute this code:
await HttpContextAccessor.HttpContext.SignOutAsync("Cookies");
but I get the following error message:
System.InvalidOperationException: 'Headers are read-only, response has already started.'
How can I prevent this error?
If you scaffolded Identity and overridden the old "LogOut.cshtml" from when you created the project via template, the Logout button won't logout. Assume you've used the default IdentityUser model. I ran into this issue and just wanted to add this if anyone else had this problem as well. I'm using Blazor Server with .Net 5.0.3's template. You can remove the Logout.cshtml.cs after as well.
Replace this \Areas\Identity\Pages\Account\LogOut.cshtml
#page
#model LogoutModel
#{
ViewData["Title"] = "Log out";
}
<header>
<h1>#ViewData["Title"]</h1>
#{
if (User.Identity.IsAuthenticated)
{
<form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="#Url.Page("/", new { area = "" })" method="post">
<button type="submit" class="nav-link btn btn-link text-dark">Click here to Logout</button>
</form>
}
else
{
<p>You have successfully logged out of the application.</p>
}
}
</header>
Replace with
#page
#using Microsoft.AspNetCore.Identity
#attribute [IgnoreAntiforgeryToken]
#inject SignInManager<IdentityUser> SignInManager
#functions {
public async Task<IActionResult> OnPost()
{
if (SignInManager.IsSignedIn(User))
{
await SignInManager.SignOutAsync();
}
return Redirect("~/");
}
}
This tripped me up too, but you need the logout functionality to be on a Razor Page (not a Blazor component). Create a Logout page and put your logout code in the OnGetAsync() method.
Your logout button can then link to the logout page.
http://lightswitchhelpwebsite.com/Blog/tabid/61/EntryId/4316/A-Demonstration-of-Simple-Server-side-Blazor-Cookie-Authentication.aspx - this is a helpful example
Don't use IHttpContextAccessor.
I guess that you're using ASP.NET Core Blazor authentication and authorization new system. If not, then start with it right now. Live is too short to be wasted over other things. This is the best product created so far for Blazor's authentication and authorization, and it is based on the Identity UI (This is not Blazor, of course). Additionally, there are a couple of Components which enable controlling the flow of authentication and authorization in your application, such as displaying a "Log in" button and a "Log out" button in your layout, interchangeably altering depending on your authentication state, etc.
Please, go to this page and start learning this excellent system, and then come here for specific issues you face:
https://learn.microsoft.com/en-us/aspnet/core/security/blazor/?view=aspnetcore-3.0&tabs=visual-studio
Hope this helps...
With Asp .Net 5 beta 6 the tag helpers do not resolve when the view is located outside the Views folder. The folder structure that I would like is one based on function rather than on file types. The controller, view models and views for a particular function I would like grouped together in a folder that reflects the controller name. Here is an example of the folder structure that I would like in the project:
UI
- Account
- AccountController.cs
- AccountViewModels.cs
- Login.cshtml
- Register.cshtml
- Students
- StudentsController.cs
- StudentsViewModels.cs
- CaptureStudent.cshtml
To accomplish this I have created a custom view engine:
public class CustomUIViewEngine : RazorViewEngine
{
public CustomUIViewEngine(IRazorPageFactory pageFactory,
IRazorViewFactory viewFactory,
IOptions<RazorViewEngineOptions> optionsAccessor,
IViewLocationCache viewLocationCache) :
base(pageFactory, viewFactory, optionsAccessor, viewLocationCache)
{
}
public override IEnumerable<string> ViewLocationFormats
{
get
{
var viewLocationFormats = base.ViewLocationFormats
.Union(new string[] { "~/UI/{1}/{0}.cshtml" });
return viewLocationFormats;
}
}
}
Which I register in startup.cs as follows:
services.AddMvc().ConfigureMvcViews(options =>
{
options.ViewEngines.Clear();
options.ViewEngines.Add(typeof(CustomUIViewEngine));
});
This custom view engine does work and the view gets located and rendered, with the only problem being that the tag helpers are not correctly rendered, so instead of seeing this:
<form method="post" class="form-horizontal" role="form" action="/Account/Login">
I am seeing this in the rendered source:
<form asp-controller="Account" asp-action="Login" method="post" class="form-horizontal" role="form">
Does anyone know why the tag helpers are not rendering correctly when the view is located outside the Views folder and if there is any way to correct this in an Asp.Net 5 web application?
Are you adding your TH's in the _ViewImports file, and if so are the using statements being recognized? Have you tried adding the #addTagHelper directly to a view?
Some of this is mentioned in my Authoring Tag Helpers
I go into to detail on inheritance hierarchy, adding, removing in an upcoming article.
I have a MVC2 web application in which i have a view containing a simple form as follows:
<%using (Html.BeginForm("Action", "Controller", FormMethod.Post, new { enctype = "multipart/form-data", #id = "frmAddNewObservationPhoto" }))
{%>
<%= Html.AntiForgeryToken()%>
<strong>1. Enter Photo Description</strong><br />
<%= Html.TextArea("photoDescription", Model.photoDescription, new { #style = "height: 100px", #id = "photoDescription" })%><br />
<strong>
2. Browse New Photo:<br />
<%= Html.HiddenFor(x => x.questionNo)%>
<%= Html.HiddenFor(x => x.observationID)%>
<input id="file" type="file" name="file">
<a class="resolveTask" href="javascript:AddNewObservationPhoto()"></a><br />
Or Select Saved Photo: <br />
</strong>
<br />
<%} %>
I have tested on desktop browsers (firefox, IE, Chrome) and the the file the user selects is posted to my action correctly. My action code begins as follows:
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult AddNewObservationPhoto(Guid observationID, string photoDescription, decimal questionNo)
{
TaskFireObservations fireObservation = FireHelper.GetObservationByID(observationID, _session);
if (Request.Files.Count > 0)
{
For completion the javascript is as follows:
function AddNewObservationPhoto() {
var photoDescription = $('#photoDescription').val();
if (photoDescription.length == 0) {
alert('Please enter the photo description');
}
else {
$('#frmAddNewObservationPhoto').submit();
}
};
My problem is that when i test this on an iPad version 6.0.1 (hence mobile safari browser), there are no files posted to the action. I have tested on the chrome browser for the ipad and it works fine on there. Ive also tested on an online ipad emulator and it works; i.e. the selected file is posted to the action and then saved to the relevant location.
Does anyone know why this would be happening? I hope ive explained the issue clearly enough.
Thanks.
I am putting this down to a bug in mobile safari as this happens intermittently, i.e. on some occasions the file is posted and on others it does nothing.
I got the DurandalJS StarterKit template on VS2012... All works great...
But in some views I need to do something like that:
#if (Roles.IsUserInRole("Administrators"))
{
<p>Test</p>
}
However with durandal all my views are '.html' files... Is that possible to use '.cshtml' files to access some information like that?
Or is there any other way to do that with durandal?
Junior
I am doing it like this:
Create a generic controller for Durandal views:
public class DurandalViewController : Controller
{
//
// GET: /App/views/{viewName}.html
[HttpGet]
public ActionResult Get(string viewName)
{
return View("~/App/views/" + viewName + ".cshtml");
}
}
Register a route:
routes.MapRoute(
name: "Durandal App Views",
url: "App/views/{viewName}.html",
defaults: new { controller = "DurandalView", action = "Get" }
);
Copy Views/web.config to /App/views/web.config (so Razor views work in this location).
This lets me use the normal Durandal conventions (even the html extension for views), and put durandal views as cshtml files in their normal location without adding any more server code.
If you also have static html views, you can also place the cshtml views in a subfolder or use the normal MVC /Views folder.
I wouldn't recommend using ASP.NET MVC with Durandal.
What you are probably looking to do is use the Razor view engine (to get the benefits of a compiler, strong typing etc.) which exists independently from ASP.NET MVC. Just WebAPI for data I/O is more than enough to very efficiently create a Durandal.js application.
If you are interested in using Razor/CSHTML with Durandal and Knockout there is an open source option out there called FluentKnockoutHelpers that may be exactly what you are looking for. It offers much of the 'nice' parts of ASP.NET MVC allowing you to use the awesome abilities of Durandal and Knockout with almost no downfalls.
Source
Live demo using Durandal.js
In a nutshell it provides a bunch of features which makes doing Durandal/Knockout development just as easy as ASP.NET MVC. (You simply provide a C# type that your JavaScript model is based off of for most of the features.) You only have to write JavaScript and un-compiled markup for complicated cases which is unavoidable and no different than MVC! (Except in MVC your code would also likely end up would also be a big jQuery mess which is why you are using Durandal/Knockout in the first place!)
Features:
Painlessly generate Knockout syntax with strongly typed, fluent, lambda expression helpers similar to ASP.NET MVC
Rich intellisense and compiler support for syntax generation
Fluent syntax makes it a breeze to create custom helpers or extend whats built in
OSS alternative to ASP.NET MVC helpers: feel free to add optional features that everyone in the community can use
Painlessly provides validation based on .NET types and DataAnnotations in a few lines of code for all current/future application types and changes
Client side JavaScript object factory (based on C# types) to create new items in for example, a list, with zero headaches or server traffic
Example without FluentKnockoutHelpers
<div class="control-group">
<label for="FirstName" class="control-label">
First Name
</label>
<div class="controls">
<input type="text" data-bind="value: person.FirstName" id="FirstName" />
</div>
</div>
<div class="control-group">
<label for="LastName" class="control-label">
Last Name
</label>
<div class="controls">
<input type="text" data-bind="value: person.LastName" id="LastName" />
</div>
</div>
<h2>
Hello,
<!-- ko text: person.FirstName --><!-- /ko -->
<!-- ko text: person.LastName --><!-- /ko -->
</h2>
Provide FluentKnockoutHelpers with a .NET type and you can do this in style with Intellisense and a compiler in Razor / CSHTML
#{
var person = this.KnockoutHelperForType<Person>("person", true);
}
<div class="control-group">
#person.LabelFor(x => x.FirstName).Class("control-label")
<div class="controls">
#person.BoundTextBoxFor(x => x.FirstName)
</div>
</div>
<div class="control-group">
#person.LabelFor(x => x.LastName).Class("control-label")
<div class="controls">
#person.BoundTextBoxFor(x => x.LastName)
</div>
</div>
<h2>
Hello,
#person.BoundTextFor(x => x.FirstName)
#person.BoundTextFor(x => x.LastName)
</h2>
Take a look at the Source or Live Demo for an exhaustive overview of FluentKnockoutHelper's features in a non-trivial Durandal.js application.
Yes, you can absolutely use cshtml files with Durandal and take advantage of Razor on the server. I assume that also means you want MVC, so you can do that too and use its routing.
If you don;t want the routing then you can set the webpages.Enabled in the web.config, as the other comments suggest.
<add key="webpages:Enabled" value="true" />
I don't recommend that you use .cshtml files as views directly. You're better off placing the .cshtml files behind a controller.
For example, take the HotTowel sample, edit /App/main.js, and replace the function definition with the following:
define(['durandal/app',
'durandal/viewLocator',
'durandal/system',
'durandal/plugins/router',
'durandal/viewEngine',
'services/logger'],
function (app, viewLocator, system, router, viewEngine, logger) {
Note that we added a reference to the Durandal viewEngine. Then we need to replace
viewLocator.useConvention();
with
viewLocator.useConvention('viewmodels', '../../dynamic');
viewEngine.viewExtension = '/';
The first argument to viewLocation.useConvention sets the /Apps/viewmodels/ directory as the location for the view models js files, but for the view location, uses the URL http://example.com/dynamic/, with an extension of '/'. So that if Durandal is looking for the view named 'shell', it will reference http://example.com/dynamic/shell/ (this is because the view directory is mapped relative to the viewmodels directory, hence /App/viewmodels/../../dynamic will give you simply /dynamic).
By convention, this previous URL (http://example.com/dynamic/shell/) will be mapped to the controller DynamicController, and the action "Shell".
After this, you simply add a controller - DynamicController.cs, like this:
// will render dynamic views for Durandal
public class DynamicController : Controller
{
public ActionResult Shell()
{
return View();
}
public ActionResult Home()
{
return View();
}
public ActionResult Nav()
{
return View();
}
public ActionResult Details()
{
return View();
}
public ActionResult Sessions()
{
return View();
}
public ActionResult Footer()
{
return View();
}
}
Create .cshtml files for each of the above actions. This way you get to use controllers, server side IoC et al to generate dynamic views for your SPA.
DurandaljS is a client framework which forms mainly a solid base for single-page apps (SPA).
I assume you are using asp.net web API as your server technology. In that case, you can determine the user's role inside your API controller and based on that return data to the client. On the client you can use Knockout "if" binding in order to show / hide certain areas of your page.
What you perhaps can do is placing this code in the Index.cshtml.
Following link shows how to customize moduleid to viewid mapping
http://durandaljs.com/documentation/View-Location/
by convention durandal tries to find view url in following steps
1) Checke whether object has getView() function which returns either dom or a string ( url for the view)
2) If object does not have getView function then checks whether object has viewUrl property
3) If above two steps fails to produce url or a DOM view drundal falls to default convention
which maps moduleid xyz.js to view xyz.html using view url ( path of Views folder ) defined in main.js
so for moduleid xyz.js path of the view will be views/xyz.html
you can overwrite this default mapping behavior by overwriting convertModuleIdToViewId function.
So there are many ways you can customize your view url for specific model (.js object)
I made an extension to Durandal which gives you the ability to place an applicationContent div in your cshtml file together with the applicationHost div. In applicationContent you can now use both ASP .Net MVC syntax together with knockout bindings.
Only thing I did was put some extra code in the viewLocator.js file which looks for an applicationContent div:
locateViewForObject: function(obj, area, elementsToSearch) {
var view;
if (obj.getView) {
view = obj.getView();
if (view) {
return this.locateView(view, area, elementsToSearch);
}
}
if (obj.viewUrl) {
return this.locateView(obj.viewUrl, area, elementsToSearch);
}
view = document.getElementById('applicationContent');
if (view) {
return this.locateView(view, area, elementsToSearch);
}
var id = system.getModuleId(obj);
if (id) {
return this.locateView(this.convertModuleIdToViewId(id), area, elementsToSearch);
}
return this.locateView(this.determineFallbackViewId(obj), area, elementsToSearch);
},
Your original cshtml file can now do something like this:
<div class="row underheader" id="applicationContent">
<div class="small-5 columns">
<div class="contentbox">
#using (Html.BeginForm("Generate", "Barcode", FormMethod.Post, Attributes.Create()
.With("data-bind", "submit: generateBarcodes")))
{
<div class="row formrow">
<label for="aantalBijlagen">#Translations.Label_AantalBijlagen</label>
</div>
<div class="row">
<select name="aantalBijlagen" class="small-6 columns">
<option>0</option>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select>
</div>
<div class="row">
<button class="button right" type="submit" id="loginbutton"><span class="glyphicon glyphicon-cog"></span> #Translations.Action_Generate</button>
</div>
}
</div>
</div>
<div class="small-7 columns" data-bind="if: hasPdfUrl">
<div class="contentbox lastcontent">
<iframe data-bind="attr: {src: pdf_url}"></iframe>
</div>
</div>
You can find my fork of the durandal project here and a small blogpost of what and how I did this here.
I'm not very familiar with DurandalJS but because it's a client-side system, it should make no difference what technology is used on the server to generate the HTML markup. So if you use Razor CSHTML files to generate the HTML on the server, DurandalJS should work just fine with it.
If you're getting a particular error then please share that error, but I can't think of any reason why it wouldn't work.