I have an action, let's say /Foo/Bar with a GET parameter in this action,
get_cached, who define if we want to get the cached value or the "realtime".
This is made with the following code :
public ActionResult Bar()
{
var useCache = Request.Params["get_cached"] == "1" ? true : false;
if (useCache)
{
return RedirectToAction("BarCached");
}
else
{
return RedirectToAction("BarRealTime");
}
}
[OutputCache(Duration = 100, VaryByParam = "*")]
public ActionResult BarCached()
{
return Content("mystuff_cached");
}
public ActionResult BarRealTime()
{
return Content("mystuff_realtime");
}
No problem with this code, apart the url will be shown as BarCached or BarRealTime and i would get only Bar (the main action name).
I tried to change the RedirectToAction to the full method name like this :
return this.BarCached()
But this disable the cache capabilities !
So, how can render the ActionResult code from a method (render BarCached from Bar) using the OutputCache definitions on this method (OutputCache on BarCached) ?
Thanks by advance.
In the asp.net pipeline, ResolveRequestCache (which OutputCache relies on) occurs just after the request is authenticated. In your example above, by the time you have gotten to "Bar" it's too late to use output caching, as you have noted by saying that this.BarCached() doesn't recognize the cache attribute.
If your problem is the performance of whatever generates "mystuff_", could you not just save the result of that call to the application cache and return it in your Bar() method instead of the RedirectToAction objects?
Not much of a solution I know, but hopefully helpful just the same.
I ended using the System.Web.Caching namespace who is the base cache handler of asp.net MVC.
I can access the cache repository of Asp.NET MVC with System.Web.HttpContext.Current.Cache
Using that, I store the ActionResult of "BarCached" and then I can get the cache feature the way I want using something like this :
Add a value to the cache
System.Web.HttpContext.Current.Cache.Insert(
"mykey",
"myvalue",
null,
DateTime.Now.AddSeconds(expirationInSeconds),
System.Web.Caching.Cache.NoSlidingExpiration
);
And get value from the cache
var myvalue = System.Web.HttpContext.Current.Cache.Get("mykey")
Related
I just started working with ASP.NET after PHP and have a question regarding using AJAX.
What is the correct methodology?
I googled that have Ajax helpers
Or use jquery code for calling methods from controller
Is it ok to return "ready" html code from controllers to view via ajax request?
For example, Now i use the same
$.post('/ControllerName/ActionFromController', { /* some params */ }, function(data){
$("#content_div").html(data);
});
my controller
public ActionResult ActionFromController()
{
// receiving parameters from AJAX request - Request.Form["parameter name"])
// to do something here
string cont = "some result of methjd works - HTML table or something else"
return cont;
}
So is it here any development methodology for using AJAX in asp.net MVC? Or is it ok to use ajax as it described above?
Almost there. The best way to bind your parameters is to strongly type them, which you can do with models. Create a model class:
public class SampleModel
{
public string ParamName1 {get;set;}
public int ParamName2 {get;set;}
}
Make sure your actions accepts this as an input:
public ActionResult ActionFromController(SampleModel model)
And when you send your ajax request specify parameters:
$.post(
'/ControllerName/ActionFromController',
{ "ParamName1": "value", "ParamName2": 1 },
function(data){
$("#content_div").html(data);
}
);
Otherwise what you have look fine.
I would suggest you to get some more information and possible results types:
JsonResult
PartialViewResult - try not to concatenate HTML in the string, return a Partial View which will contain HTML constructed based on model (for example some parameters from the ajax request. Useful resources: Partial View in ASP.NET MVC, Updating an MVC Partial View with Ajax
I am migrating an ASP.NET application to ASP.NET Core and they have some calls to HttpServerUtility.Transfer(string path). However, HttpServerUtility does not exist in ASP.NET Core.
Is there an alternative that I can use? Or is Response.Redirect the only option I have?
I want to maintain the same behaviour as the old application as much as possible since there is a difference in between Server.Transfer and Response.Redirect.
I see some options for you, depending on your case:
Returning another View: So just the HTML. See answer of Muqeet Khan
Returning another method of the same controller: This allows also the execution of the business logic of the other action. Just write something like return MyOtherAction("foo", "bar").
Returning an action of another controller: See the answer of Ron C. I am a bit in troubles with this solution since it omits the whole middleware which contains like 90% of the logic of ASP.NET Core (like security, cookies, compression, ...).
Routing style middleware: Adding a middleware similar to what routing does. In this case your decision logic needs to be evaluated there.
Late re-running of the middleware stack: You essentially need to re-run a big part of the stack. I believe it is possible, but have not seen a solution yet. I have seen a presentation of Damian Edwards (PM for ASP.NET Core) where he hosted ASP.NET Core without Kestrel/TCPIP usage just for rendering HTML locally in a browser. That you could do. But that is a lot of overload.
A word of advice: Transfer is dead ;). Differences like that is the reason for ASP.NET Core existence and performance improvements. That is bad for migration but good for the overall platform.
You are correct. Server.Transfer and Server.Redirect are quite different. Server.Transfer executes a new page and returns it's results to the browser but does not inform the browser that it returned a different page. So in such a case the browser url will show the original url requested but the contents will come from some other page. This is quite different than doing a Server.Redirect which will instruct the browser to request the new page. In such a case the url displayed in the browser will change to show the new url.
To do the equivalent of a Server.Transfer in Asp.Net Core, you need to update the Request.Path and Request.QueryString properties to point to the url you want to transfer to and you need to instantiate the controller that handles that url and call it's action method. I have provided full code below to illustrate this.
page1.html
<html>
<body>
<h1>Page 1</h1>
</body>
</html>
page2.html
<html>
<body>
<h1>Page 2</h1>
</body>
</html>
ExampleTransferController.cs
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
namespace App.Web.Controllers {
public class ExampleTransferController: Controller {
public ExampleTransferController() {
}
[Route("/example-transfer/page1")]
public IActionResult Page1() {
bool condition = true;
if(condition) {
//Store the original url in the HttpContext items
//so that it's available to the app.
string originalUrl = $"{HttpContext.Request.Scheme}://{HttpContext.Request.Host}{HttpContext.Request.Path}{HttpContext.Request.QueryString}";
HttpContext.Items.Add("OriginalUrl", originalUrl);
//Modify the request to indicate the url we want to transfer to
string newPath = "/example-transfer/page2";
string newQueryString = "";
HttpContext.Request.Path = newPath;
HttpContext.Request.QueryString = new QueryString(newQueryString);
//Now call the action method for that new url
//Note that instantiating the controller for the new action method
//isn't necessary if the action method is on the same controller as
//the action method for the original request but
//I do it here just for illustration since often the action method you
//may want to call will be on a different controller.
var controller = new ExampleTransferController();
controller.ControllerContext = new ControllerContext(this.ControllerContext);
return controller.Page2();
}
return View();
}
[Route("/example-transfer/page2")]
public IActionResult Page2() {
string originalUrl = HttpContext.Items["OriginalUrl"] as string;
bool requestWasTransfered = (originalUrl != null);
return View();
}
}
}
Placing the original url in HttpContext.Items["OriginalUrl"] isn't strictly necessary but doing so makes it easy for the end page to know if it's responding to a transfer and if so what the original url was.
I can see this is a fairly old thread. I don't know when URL Rewriting was added to .Net Core but the answer is to rewrite the URL in the middleware, it's not a redirect, does not return to the server, does not change the url in the browser address bar, but does change the route.
resources:
https://weblog.west-wind.com/posts/2020/Mar/13/Back-to-Basics-Rewriting-a-URL-in-ASPNET-Core
https://learn.microsoft.com/en-us/aspnet/core/fundamentals/url-rewriting?view=aspnetcore-5.0
I believe you are looking for a "named view" return in MVC. Like so,
[HttpPost]
public ActionResult Index(string Name)
{
ViewBag.Message = "Some message";
//Like Server.Transfer() in Asp.Net WebForm
return View("MyIndex");
}
The above will return that particular view. If you have a condition that governs the view details you can do that too.
I know that this is a very old question, but if someone uses Razor Pages and is looking to a Server.Transfer alternative (or a way to return a different view depending on a business rule), you can use partial views.
In this example, my viewmodel has a property called "UseAlternateView":
public class TestModel : PageModel
{
public bool UseAlternateView { get; set; }
public void OnGet()
{
// Here goes code that can set UseAlternateView=true in certain conditions
}
}
In my Razor View, I renderize a diferent partial view depending of the value of the UseAlternateView property:
#model MyProject.Pages.TestModel
#if (Model.UseAlternateView)
{
await Html.RenderPartialAsync("_View1", Model);
}
else
{
await Html.RenderPartialAsync("_View2", Model);
}
The partial views (files "_View1.cshtml" and "_View2.cshtml"), contain code like this:
#model MyProject.Pages.TestModel
<div>
Here goes page content, including forms with binding to Model properties
when necessary
</div>
Obs.: when using partial views like this, you cannot use #Region, so you may need to look for an anternative for inserting scripts and styles in the correct place on the master page.
I have a route:
routes.MapRoute("ResetPasswordConfirm", "reset-password-confirm", new { controller = "Membership", action = "ResetPasswordConfirm" });
and the code
public ActionResult ResetPasswordConfirm(int userid, string key)
{
// ...
}
in my application. So that i have url to be executed like this:
http://localhost/reset-password-confirm?userid=1&key=bla_bla_something
That is absolutely okay, until someone decides to go to
http://localhost/reset-password-confirm
...and look what will happen. ASP.NET will generate predictable error:
The parameters dictionary contains a null entry for parameter 'userid' of non-nullable type 'System.Int32'...
It could be done also by a search robot trying to grab all the possible urls. It's okay, but generates a lot of errors during usage of application in the wild. I want to avoid that, but feel uncomfortable with writing a stub for every possible case for such kind of errors.
Is there any elegant way of doing that? Thanks.
Another way is to handle global errors, just set <customErrors mode="On"></customErrors> on your web.config and create an Error.cshtml on your Shared view folder. MVC3 templates actually include that page.
On the other hand, if you want to be more specific, you should try Action Filters, that's a cool way to handle errors.
[HandleError(View = "YourErrorView", ExceptionType=typeof(NullReferenceException))]
public ActionResult ResetPasswordConfirm(int? userid, string key)
{
if (!userid.HasValue)
throw new NullReferenceException();
// ...
}
Use nullables for your parameters, i.e.:
public ActionResult ResetPasswordConfirm(int? userid, string key)
I am new to MVC, so hopefully my question will be straight forward. I am thinking of a scenario where the user submits a form (that is a partial view) and it undergoes server validation. I am wondering how I will know the result of the validation on the client side (javascript) after the form is submitted. For example, if validation fails I will obviously want to return the partial view again with validation messages set, but if it passes validation I may not necessarily want to return the partial view. I may want to return a json object with a message or hide a div or something. I want to be able to determine the validation result on the client. Is something like that possible? Or can I approach this a different way?
The tricky part with AJAX is that the client and server both have to agree on what's supposed to come back from the server in any circumstance. You have a few options:
Your server will always return HTML, and jQuery will always replace the editor content with the HTML that comes back. If the model is invalid, you return a PartialView result. If the model is valid, you return a <script> tag that tells the page what it needs to do (e.g. close a dialog, redirect to a different page, whatever). jQuery will automatically run any script it finds in the results when it tries to insert them into the DOM.
Your server will always return a JSON object representing what happened. In this scenario, your client-side javascript code has to be complex enough to take the results and modify your page to match. Under normal circumstances, this will mean that you don't get to take advantage of MVC's validation features.
Same as 2, except that you use a custom utility method to render the partial view you want into a string, and you make that entire string part of the JSON that comes back. The javascript code then just has to be smart enough to check whether the JSON shows a valid or invalid result, and if the result is valid, replace the contents of your editor area with the partialview HTML that is returned as part of the JSON object you got back.
Same as 3, except you develop an event-based architecture where all your AJAX requests will always expect to get back a JSON object with one or more "events" in it. The AJAX code can then be consolidated into one method that hands the events off to an Event Bus. The event bus then passes the event information into callbacks that have "subscribed" to these events. That way, depending on what kind of events you return from the server, you can have different actions occur on the client side. This strategy requires a lot more up-front work to put in place, but once it's done you can have a lot more flexibility, and the client-side code becomes vastly more maintainable.
Partial views would not have a Layout page. You may use this code to check if the view is rendered as partial view.
#if (String.IsNullOrWhiteSpace(Layout))
{
// Do somthing if it is partial view
}
else
{
// Do somthing if it is full page view
}
If you are using the MVC Data Annotations for validating your Model, then the controller will have a property called ModelState (typeof(ModelStateDictionary) which as a property of IsValid to determine if your Model passed into the Controller/Action is valid.
With IsValid you can return a Json object that can tell your Javascript what to do next.
Update
Here is a really basic example (USES jQuery):
[SomeController.cs]
public class SomeController : Controller
{
public ActionResult ShowForm()
{
return View();
}
public ActionResult ValidateForm(MyFormModel FormModel)
{
FormValidationResults result = new FormValidationResults();
result.IsValid = ModelState.IsValid;
if (result.IsValid)
{
result.RedirectToUrl = "/Controller/Action";
}
this.Json(result);
}
}
[FormValidationResult.cs]
public class FormValidationResults
{
public bool IsValid { get; set; }
public string RedirectToUrl { get; set; }
}
[View.js]
$(document).ready(function()
{
$("#button").click(function()
{
var form = $("#myForm");
$.ajax(
{
url: '/Some/ValidateForm',
type: 'POST',
data: form.serialize(),
success: function(jsonResult)
{
if (jsonResult.IsValid)
{
window.location = jsonResult.RedirectToUrl;
}
}
});
});
});
The populated catList is always Count=0 when the code jumps to CreateProduct() so I take it it does not get delivered.
Considering RouteValueDictionary does not do this ? Any other way?
public ActionResult GetCats(int CatID)
{
List<Category> catList = new List<Category>();
if (CatID >= 0 )
{
catList = context.Categories.Where(x => x.PCATID == CatID).ToList();
}
return RedirectToAction("CreateProduct", "Admin", new { catList });
}
public ActionResult CreateProduct(List<Category> catList) { }
You are actually trying to use controllers to do data access.
Move the "GetCats" data retrieval into your business layer (Service object, Repository, whatever suits you).
Then, CreateProduct will need to be there twice (2 signatures). One with no parameters in which you are going to call "GetCats" from your business layer and send it to the view.
The other implementation is going to be the flagged with the HttpPostAttribute and will contain in parameters all the necessary information to create a cat.
That's all. Simple and easy.
You could place any items that you need in TempData then call RedirectToAction.
RedirectToAction simply returns a "302" code to the browser with the URL to redirect to. When this happens your browser performs a GET with that URL.
Your RouteValues need to be simple. You can't really pass complex object or collections using a route value.
if you don't care about the browser url changing you could just
return CreateProduct(catList)