I have a link on a grid in my AdminUsers view
grid.Column(header: "", format: (item) => (condition ? Html.ActionLink("Impersonate", "Impersonate", "Admin", new { id = item.username }, null) : Html.Label("Impersonate"), style: "webgrid-column-link"),
In the controller, I have
public ActionResult Impersonate(string id)
{
string result = ORCA.utilities.users.setImpersonation(id);
if(result == "nocommonfields")
return RedirectToAction("AdminUsers", "Admin");
else
return RedirectToAction("terms_of_use", "Forms");
}
How can send an error message to display when I return to the AdminUsers page?
You may use TempData
if(result == "nocommonfields")
{
TempData["ErrorMessage"]="This is the message";
return RedirectToAction("AdminUsers", "Admin");
}
and in your AdminUsers action, you can read it
public ActionResult AdminUsers()
{
var errMsg=TempData["ErrorMessage"] as string;
//check errMsg value do whatever you want now as needed
}
Remember, TempData has very short-life span. Session is the backup storage behind temp data.
Alternatively, You may also consider sending a flag in your querystring and read it in your next action method and decide what error message to show.
The TempData controller property can be used to achieve this kind of functionality. Its main drawback in my opinion is that it uses the session storage in to store its contents. This means that you'll have extra work getting it to function on a web farm, or that you need to turn on sessions in the first place.
The good thing about TempData is that is exactly does what you want. Its a string based dictionary and you can put anything in it and by default get it out only once. So before calling RedirectToAction() you set your message. On the next request you check for messages and display them. By retrieving the messages they are automatically deleted at the end of the request.
As an alternative you could use cookies for transporting the message between the two requests. Essentially you could either roll your own solution, or implement a custom ITempDataProvider which transports the contents of TempData via cookies. Note that you need to properly secure cookies. MachineKey.Protect() can help you if you are rolling your own.
I was facing the same problem you did and created a solution for it called FlashMessage. Perhaps this could save you some work. It's available on NuGet as well. Usage is simple: you simply queue a message before you call RedirectToAction() as follows:
if(result == "nocommonfields")
{
FlashMessage.Warning("Your error message");
return RedirectToAction("AdminUsers", "Admin");
}
In your view you include the following statement to render any previously queued messages:
#Html.RenderFlashMessages()
Related
I have Developed ASP.net Core Web API & Web APP Which are in the same solution but different projects.
in the API I have some validations/checking as you may call.
e.g: if user email already exists, the API returns 'Email alreday in use' like this
bool EmailExists = dbContext.Users.Any(u => u.Email == user.Email);
if (EmailExists)
{
return new JsonResult("Email Address already taken!, Try a differen Email");
}
and so on. in some cases I may need to check multiple columns one a time, (eg: UserName, Email, TellNum)
This is an example of calling the API in the MVC
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(_baseAPIUrl);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage Res = await client.PostAsJsonAsync("Users", user);
if (Res.IsSuccessStatusCode)
{
//in here I want check the `Res` and if it contains the returned messages, I want to display them by assigning it to `TempData[infoMsg]`
// else some something(register user)
}
// Check the returned JsonResult messages here if statusCode is ultered eg: BadRequest
}
My Question is how can I display these types of response messages in razor view in the MVC(Web App). in PostMan its workin, returning the response messages in body.
I did a lot of research about this but couldn't come to conclusion. I also cantacted some Devs I know(not .NET) and they said use JavaScript to call your API, which means I have to change almost everything I have done so far.
I aslo tried ultereing the statuCode to something like BadRequest in the API(if Email exists) in which case it will be checked outside the if (Res.IsSuccessStatusCode) of the Httpclient.
any help or direction is highly appreciated.
You should return a http error and a body containing some data about it eg field and message to your mvc controller. That could be a 422 error or whatever you like really since it's effectively internal and just coming back to the mvc controller.
The controller can then add any such error to modelstate and you can use the razor model "client" validation mechanism to show the error associated with a field.
This is therefore using the same mechanism used for attribute validation in the controller where you'd do
if (!ModelState.IsValid)
This is air code but will hopefully give you the idea.
[HttpPost]
public ActionResult PostUpdate(User u)
{
// call service and await response
var response = await httpClient.PostAsJsonAsync(posturi, u);
var returnContent = await response.Content.ReadAsAsync<ReturnContent>();
if (response.Result != HttpStatusCode.OK)
{
ModelState.AddModelError(returnContent.FieldName,returnContent.Error);
return Page();
}
// etc
You will want a more sophisticated checking on errors of course and check you get the body you're expecting.
Maybe you just hard code the field and error message if there's only one possibility. Maybe work with an array of fields and errors if there could be numerous validation fails.
In my Controller I have a function which helps me check for any Session timeouts, this works fine and it directs the users to an error page. Unfortunately from here I really just have the option to go back to the homepage, what I would like is to create the functionality to take them back to the previous page.
Each page will have a form of ID attached in the query string (this isn't always called ID, but it is always a unique number to identify the object.
What I need is to try and get this ID (always the first parameter / key) and use this as a basis to create the ActionLink on the view. I can get the RawUrl using the ActionExecutedContext which contains the requesting raw URL, but I'm unsure how to actuall make this useful.
The following is the code which executes after my Action, it validates if the user has timed out and moves them to an error page. The ErrorId of -1001 is just to identify that this is a timeout. What I need is an ID, similar to what I can kind of see in the RawUrl property, which I can then use as part of the RedirectToAction to take the user back to the original page.
protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
if (filterContext.HttpContext.Session != null)
{
if (filterContext.HttpContext.Session.IsNewSession)
{
string cookie = filterContext.HttpContext.Request.Headers["Cookie"];
if ((cookie != null) && (cookie.IndexOf("ASP.NET_SessionId") >= 0))
{
filterContext.Result = RedirectToAction("Error", new { errorId = -1001, errorMessage ="Your session has timed out.Please restart the application or click 'Home' below."});
return;
}
}
base.OnActionExecuted(filterContext);
}
}
... and it directs the users to an error page.
When making this redirect pass as query string parameter a ReturnUrl. This parameter will be the current request url.
Then inside the error page you will be able to use this ReturnUrl query string parameter to build an anchor or a form pointing to the initially requested resource. For example:
Go back
I have a controller action in my project that has a situation where it needs to display an error message to the user under certain scenarios. This action occurs in a POST:
[HttpPost]
public ActionResult DoSomeAction() {
if( someCondition )
return RedirectToAction("SomeActionError");
return RedirectToAction("Index");
}
public ActionResult SomeActionError() {
return View();
}
Currently I have it set up so that it will redirect to an error controller action. I'm not really fond of this approach because in the URL they see /SomeActionError and it also means that the user can directly navigate to this URL.
Is it a bad design/approach to put some flag in TempData and redirect to another controller that checks for the TempData error flag?
Example:
[HttpPost]
public ActionResult DoSomeAction() {
if( someCondition ) {
TempData["DoSomeActionError"] = true;
}
return RedirectToAction("Index");
}
public ActionResult Index() {
// check for error
if( TempData["DoSomeActionError"] ) {
return View("SomeActionError");
}
}
Is this a bad idea? Is there another approach that does something similar (doesn't allow the user to directly navigate to the error action)? I don't want to return the View on the POST action because I don't want them to refresh and cause another POST.
TempData is not per se a bad concept. TempData is for transporting an information to some consumer that reads that information and the information should vanish after it's been read.
The way your're using TempData is odd. A more elegant implementation for your requirements (you should show an error message) is to implement an equivalent to the rails flash concept and don't redirect to an error page but display an error message in your index view. Something like a red banner that says "The record could not be saved".
This question shows a nice flash implementation including the view stuff (not the accepted answer but the answer by #jim)
using tempdata in mvc is not a good approach.
If i were you i'll do as following:
[HttpPost]
public ActionResult DoSomeAction() {
if( someCondition ) {
return RedirectToAction("Index", new{error=true}
}
return RedirectToAction("Index");
}
public ActionResult Index(bool? error) {
// check for error
if(error?? false ) {
return View("SomeActionError");
}
}
While I don't agree TempData is always bad (I find it great for status messages I absolutely don't want passed on the url such as "record saved", I think in your case there may be a better option.
First you don't want an error page to be accessible - may I ask why?
To do a redirect when an error happens only to redirect again is a bit odd. I would throw the exception and handle that exception by your error view. MVC automatically adds the [HandleError] attribute as a global filter, so throw your exception (a custom type if necessary) and handle it in your error page as you see fit since you can access exception details there and it doesn't require a redirect.
I am using Http Handler ashx file for showing the images.
I was using Session object to get image and return in the response
Now problem is i need to use custom Session object its nothing but the Wrapper on HttpSession State But when i am trying to get existing custom session object its creating new ...
its not showing session data , i checked the session Id which is also different
Please adive how can i get existing session in ashx file ?
Note: When i use ASP.NET Sesssion its working fine
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class GetImage : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{
When you want to get access to your Session State from an ASHX or HttpHandler you need to implement IReadOnlySessionState or IRequiresSessionState if you need read/write access.
The fact that it's an ashx should be irrelevant - assuming the request is being spawned off a request from an exsiting session; I'm assuming it should be - but it might pay to check exactly how the request is being formed. Always pays to go back to basics :)
Assuming that's ok, this is how I've been doing it:
string sessionId = string.Empty;
System.Web.SessionState.SessionIDManager sessionIDManager = new System.Web.SessionState.SessionIDManager();
bool supportSessionIDReissue;
sessionIDManager.InitializeRequest(httpContext, false, out supportSessionIDReissue); sessionId = sessionIDManager.GetSessionID(httpContext);
if (sessionId == null)
{
// Create / issue new session id:
sessionId = sessionIDManager.CreateSessionID(httpContext);
}
At the end of this the sessionId variable will (should) contain the existing Session ID, or a newly created one that you can reuse later..
you can just use a Actionresult rather than a handler for this
return new FileStreamResult(new FileStream(path, FileMode.Open), "image/jpeg");
or
return(new FileResult(Pathtoimage, "image/jpeg"));
that should make things easier as you wil be using a controll/action as your url
ie
<img src="/Images/showImage/1">
you can then have your actions deal with anything like pulling from db as bytes
streaming, check validation etc
SHORT:
How do I make a controller return the current view or just simply do nothing?
LONG:
I have a partial view where i've created an imageslider.
It contains a link which sends a request to a controller to get the next image (using ajax).
The controller fetches the next image, stores it in ViewData and sends back a partial view (the one above).
Now, what I do today is that when the controller reaches the last image it re-return the very same image (by refetching it), but still creates a new view, that is, the client/browser re-parses the "same" data.
This seems somewhat non-optimal.
What I'd like to do is that when controller reaches the last image it should simply do nothing.
If I return null then the view is updated with empty contents.
I want the view/client/browser to retain whatever it has and the controller to simply do nothing.
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult GetNextImage(...)
{
if(Request.IsAjaxRequest())
{
if(CURRENT_IMAGE != LAST_IMAGE)
{
Image image = GetNextImage(...);
var partialViewResult = new PartialViewResult();
partialViewResult.ViewName = "ImageSlide";
partialViewResult.ViewData.Model = image;
return partialViewResult;
}
else
{
// DO NOTHING, HOW?
}
}
return RedirectToAction("Error", "Home");
}
You can return an EmptyResult if you want it to do nothing...
return new EmptyResult();
If you're using the AjaxHelper you can avoid the update by supplying an unsuccessful status code (e.g. 404 or whatever is most appropriate), that'll stop it replacing your div as the javascript in MicrosoftMvcAjax.js explicitly checks for a successful response before updating any elements:-
this.ControllerContext.HttpContext.Response.StatusCode = 404;
return new EmptyResult();
Ultimately the best way to avoid it is to design the partial view so it avoids the problem in the first place (like you mention yourself).
I ran into this problem today. I wanted to find a solution for how to deal with double-clicks on the client side trying to reenter the controller action on the server side while it was still processing. If a user entered that action, I wanted it to just ignore the request and do nothing on the browser side.
Solution looks like this:
public async Task<ActionResult> MyAction()
{
if(!CanEnterAction(nameof(MyAction))) return new HttpStatusCodeResult(204);
try
{
// Do long running stuff
return ValidActionResult();
}
finally
{
ExitedAction(nameof(MyAction));
}
}
Returning a status code of 204 basically does nothing to the page displayed in the browser. The actual result eventually makes it back to the browser when the action is complete.
This question is old, but I wasn't able to find an answer anywhere on StackOverflow. I figured it had to be possible since a FileResult doesn't really affect the current page, either, other than saving a file.
I would use
return new HttpStatusCodeResult(204);
this way you would stay on the same page and there is no post back.
Here is the defination
The HTTP 204 No Content success status response code indicates that the request has succeeded, but that the client doesn't need to go away from its current page
Assuming that you are using MicrosoftMvcAjax, you could send back a JavascriptResult that alerts the user that they have reached the end of the slider. If the response is javascript rather than content, the MicrosoftMvcAjax handler executes it instead of replacing the DOM contents.
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult GetNextImage(...)
{
if(Request.IsAjaxRequest())
{
if(CURRENT_IMAGE != LAST_IMAGE)
{
Image image = GetNextImage(...);
var partialViewResult = new PartialViewResult();
partialViewResult.ViewName = "ImageSlide";
partialViewResult.ViewData.Model = image;
return partialViewResult;
}
else
{
return JavaScript( "alert('No more images');" );
}
}
return RedirectToAction("Error", "Home");
}
Of course, you'd probably want to be more creative and use the jQuery dialog plugin or something rather than an alert.
Ok, I've got it.
Not a solution to my question but still solves the problem.
I'll simply not show the "Next" link when the view shows the last image.
Can't believe I didn't think of it earlier...
Thanks for your efforts guys