My controller is something like this:
[HttpPost]
[Route("Somewhere")]
public JsonResult SetSomething(string propertyName, string propertyValue)
{
var successSave = this.SaveIt(propertyName,propertyValue);
if(successSave)
return Json(propertyValue);
else
// Show a message in front end that there was problem in saving
}
And then my view is currently something like:
#Model.SomethingFeild
That just loads the value and shows it in a textbox field in there .
So how can I change this to be able to handle the psedo-code scenario I wrote in the controller, so that if something is wrong in DB ( not front-end vlaidation) such as duplicate entry, then it comes back and tells the UI that so UI shows a hard coded message?
Wrap it in try catch block and add an extension method for reading exception (or your exception type that is thrown) like so:
[HttpPost]
[Route("Somewhere")]
public JsonResult SetSomething(string propertyName, string propertyValue)
{
try
{
var successSave = this.SaveIt(propertyName, propertyValue);
if (successSave)
return Json(new { success = true, value = propertyValue });
}
catch (Exception ex)
{
return Extensions.ReturnExceptionToView(ex);
}
}
Example extension method (static method):
internal static JsonResult ReturnExceptionToView(Exception ex)
{
List<object> viewErrors = new List<object>();
viewErrors.Add(new { ErrorMessage = ex.ToString() });
return new JsonResult() { Data = (new { success = false, errors = viewErrors }) };
}
Then check for success property in the response in JS. Example below is using response of ajax call and pushing to Knockout observable array.
if (response.success) {
// do something with successful response
} else {
// we have an error in the response.errors collection
$.each(response.errors, function () {
vm.saveErrors.push(new ErrorMsg(this.ErrorMessage));
});
Related
I am implementing an authorization mechanizm for my MVC application via Custom Action Filters.
I have provided the following Custom Action Filter for authorization:
[AttributeUsageAttribute(AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
public class AuthorizationFilterAttribute : ActionFilterAttribute
{
public AuthorizationEntity Entity { get; set; }
public AuthorizationPermission Permission { get; set; }
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
AuthorizationResult result = null;
// Base actions (Authentication first)
base.OnActionExecuting(filterContext);
BaseController controller = filterContext.Controller as BaseController;
if (controller != null)
{ // Base actions (Authorizatioın next)
User usr = controller.currentUser;
AuthorizationResult ar = AuthorizationManager.GetAuthorizationResult(this.Entity, this.Permission, usr.UserId, usr.RoleId);
if (!ar.IsAuthorized)
{
throw new UnauthorizedAccessException(ar.Description);
}
// Authorized, continue
return;
}
}
}
And in my Base Controller class I am handling UnauthorizedAccessException type Exceptions and redirect them to a warning page via the following code
protected override void OnException(ExceptionContext filterContext)
{
if (filterContext.Exception is UnauthorizedAccessException)
{
if (!filterContext.HttpContext.Request.IsAjaxRequest())
{
Exception ex = filterContext.Exception;
filterContext.ExceptionHandled = true;
filterContext.Result = new ViewResult()
{
ViewName = "UnauthorizedAccess"
};
}
else
{
throw filterContext.Exception;
}
}
}
This mechanism is OK for actions which return ActionResult. But I also have some AJAX calls, which I don't want to redirect to a warning page but would ilke to display a warning pop-up instead. Thi is why I have checked if the request is an Ajax call is not.
I am using the following code to make Ajax calls:
$.ajax({
type: "POST",
url: "AjaxPostMethodName",
dataType: "json",
data:
{
postval: [some value here]
},
success: function (msg) {
// Do some good actions here
},
error: function (x, t, m, b) {
// Display error
alert(m);
}
})
which goes to the following method on the Controller
public JsonResult AjaxPostMethodName(string postval)
{
try
{
// Some cool stuff here
return Json(null);
}
catch (Exception ex)
{
Response.StatusCode = UNAUTHORIZED_ACCESS_HTTP_STATUS_CODE;
return Json(ex.Message);
}
}
But when I fail the authorization check it directly shows the "Internal Server Error" message instead of falling to the catch block of AjaxPostMethodName method and displaying the proper message.
How can I make such code display filterContext.Exception instead of static "Internal Server Error" message?
Regards.
I finally found the answer to my solution in another Stack Overflow post (Can I return custom error from JsonResult to jQuery ajax error method?). I should use JsonExceptionFilterAttribute as follows:
public class JsonExceptionFilterAttribute : FilterAttribute, IExceptionFilter
{
public void OnException(ExceptionContext filterContext)
{
if (filterContext.RequestContext.HttpContext.Request.IsAjaxRequest())
{
filterContext.HttpContext.Response.StatusCode = 500;
filterContext.ExceptionHandled = true;
string msg = filterContext.Exception.Message;
if (filterContext.Exception.GetType() == Type.GetType("System.UnauthorizedAccessException"))
{
msg = "Unauthorized access";
}
filterContext.Result = new JsonResult
{
Data = new
{
errorMessage = msg
},
JsonRequestBehavior = JsonRequestBehavior.AllowGet
};
}
}
}
Your OnException method will get called when there is Unhandled exception in your code. And in your ajax method AjaxPostMethodName you have put your code in try catch blcok. So any exception in this method will not go to your OnException method.
I've just checked the Response.StatusCode behavior and for me it works.
Index.cshtml
#{
ViewBag.Title = "Index";
}
<h2>Index</h2>
<script type="text/javascript">
$(document).ready(function () {
alert('doc ready');
$.ajax({
type: "POST",
url: '#Url.Action("AjaxPostMethodName")',
dataType: "json",
data:
{
test: '10'
},
success: function (msg) {
// Do some good actions here
alert('success');
alert(msg);
},
error: function (x, t, m, b) {
// Display error
alert('error');
}
});
});
</script>
HomeController.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
namespace MvcApplication1.Controllers
{
public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
[HttpPost]
public JsonResult AjaxPostMethodName(string postval)
{
Response.StatusCode = 401;
return Json("test");
}
}
}
When I set Response.StatusCode to 200 it calls success, when 401 it calls error.
Please verify whether other parts of your code don't interfere with it somehow.
You could try also following workaround - if AjaxPostMethodName throws exception returned JSON has a flag isValid and a message errorMessage, so in your ajax success method you can just check whether isValid is okay and handle error.
I'm trying to post a list of objects from my winforms application to my asp.net mvc 4 website. I've tested posting one object, and it works, but does not work for the list. It returns a 500 (Internal Server Error). Here is my code:
ASP.NET MVC Web API
public class PostTraceController : ApiController
{
public HttpResponseMessage Post(List<WebTrace> list)
{
try
{
// Some code
return Request.CreateResponse(HttpStatusCode.Created);
}
catch (Exception ex)
{
HttpContext.Current.Trace.Write("exception", ex.Message);
return Request.CreateErrorResponse(HttpStatusCode.ServiceUnavailable, ex);
}
}
public HttpResponseMessage Post(WebTrace item)
{
try
{
// Some code
return Request.CreateResponse(HttpStatusCode.Created);
}
catch (Exception ex)
{
HttpContext.Current.Trace.Write("exception", ex.Message);
return Request.CreateErrorResponse(HttpStatusCode.ServiceUnavailable, ex);
}
}
}
Win forms application
public class BaseSender
{
public BaseSender()
{
Client = new HttpClient
{
BaseAddress = new Uri(#"http://localhost/mywebsite/")
};
Client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
}
public string UserCode { get; set; }
protected readonly HttpClient Client;
public HttpResponseMessage PostAsJsonAsync(string requestUri, object value)
{
var response = Client.PostAsJsonAsync(requestUri, value).Result;
response.EnsureSuccessStatusCode();
return response;
}
}
public class WebTraceSender : BaseSender
{
private const string requestUri = "api/posttrace";
public bool Post(List<ArchiveCptTrace> list)
{
try
{
var listWebTrace = new List<WebTrace>();
foreach (var item in list)
{
listWebTrace.Add(new WebTrace
{
DateStart = item.DatePreparation,
DateEnd = item.DateCloture,
UserStart = item.UserPreparation.UserName,
UserEnd = item.UserCloture.UserName,
AmountStart = item.MontantPreparation,
AmountEnd = item.MontantCloture,
TheoricAmountEnd = item.MontantTheorique,
Difference = item.Ecart,
UserCode = UserCode
});
}
var responce = PostAsJsonAsync(requestUri, listWebTrace);
return responce.IsSuccessStatusCode;
}
catch (Exception e)
{
// TODO : Trace the exception
return false;
}
}
}
EDIT :
I've found out the scenario of the error, which is having two methods in my api controller, even thought they have different signature. If I comment one method, the post work fine (item or a list). Any ideas ?
The methods may have different signatures, but Web API can't tell the difference between them without inspecting the body, which it won't do for performance reasons.
You could do two things - either create a new class which just holds a list of WebTrace objects, and put that in a different API controller, or you could map a custom route to one of your existing methods. You could do that with ActionName attribute, however, I would probably take the first approach.
I have a property on my Model Class that performs a type conversion as follows:
Model:
public class TimeClass
{
private int timeInSeconds;
[Required]
public int Id {get;set;}
[Required]
public string Timer
{
get {
TimeSpan ts = new TimeSpan(0,0,(int)timeInSeconds);
return ts.ToString(#"mm\:ss",CultureInfo.InvariantCulture);
}
set {
try {
var ts = TimeSpan.ParseExact(value, #"mm\:ss", CultureInfo.InvariantCulture);
timeInSeconds= Convert.ToInt32(ts.TotalSeconds);
}
catch {
//Is it possible to add a validation error to the modelstate here
}
}
}
}
Controller:
[HttpPost]
public ActionResult Create(FormCollection collection)
{
string[] whitelist = new[] {"Id", "Timer" };
if (TryUpdateModel(quiz, whitelist))
{
//Save to Repo
return RedirectToAction("Edit", new { Id = Id });
}
return View(tc);
}
What is the appropriate pattern to add an appropriate ModelError if the TimeSpan.Parse throws an exception?
Currently it will give the generic error "The value "xxx" is invalid". How can I customize this to return a specific error?
Rather than putting the try catch within your model, you could move the error handling to your controller code. For example if the tryupdatemodel throws an exception you could add a custom model error:
TimeClass model = new TimeClass();
string[] whitelist = new[] {"Id", "Timer" };
try
{
UpdateModel(model);
//Save to Repo
return RedirectToAction("Edit", new { Id = Id });
}
catch
{
// Generate error
ModelState.AddModelError(string.Empty, "Model Error Here");
return View(tc);
}
I have a controller method that returns a void because it is building an Excel report for the user to download. The Excel 3rd party library we're using is writing to the response itself. The method looks something like this:
[HttpGet]
public void GetExcel(int id)
{
try
{
var report = _reportService.GetReport(id);
var table = _reportService.GetReportTable(id);
var excelReport = new ExcelReport(table, report.Name);
excelReport.DownloadReport(System.Web.HttpContext.Current.Response);
}
catch (Exception ex)
{
// This is wrong, of course, because I'm not returning an ActionResult
Response.RedirectToRoute("/Report/Error/", new { exceptionType = ex.GetType().Name });
}
}
There are several security checks in place that throw exceptions if the user doesn't meet certain credentials for fetching the report. I want to redirect to a different page and pass along some information about the exception, but I can't figure out how to do this in MVC3....
Any ideas?
You could use the following code
Response.Redirect(Url.Action("Error", "Report", new { exceptionType = ex.GetType().Name }));
But have you taken a look at the FilePathResult or FileStreamResult ?
Instead of letting the 3rd part library write to the response directly get the content use regular ActionResult and return File(...) for the actual file or RedirectToAction(...) (or RedirectToRoute(...)) on error. If your 3rd party library can only write to Response you may need to use some tricks to capture it's output.
[HttpGet]
public ActionResult GetExcel(int id)
{
try
{
var report = _reportService.GetReport(id);
var table = _reportService.GetReportTable(id);
var excelReport = new ExcelReport(table, report.Name);
var content = excelReport.MakeReport(System.Web.HttpContext.Current.Response);
return File(content, "application/xls", "something.xls");
}
catch (Exception ex)
{
RedirectToRoute("/Report/Error/", new { exceptionType = ex.GetType().Name });
}
}
You can return an EmptyActionResult:
[HttpGet]
public ActionResult GetExcel(int id)
{
try
{
var report = _reportService.GetReport(id);
var table = _reportService.GetReportTable(id);
var excelReport = new ExcelReport(table, report.Name);
excelReport.DownloadReport(System.Web.HttpContext.Current.Response);
return new EmptyResult();
}
catch (Exception ex)
{
return RedirectToAction("Error", "Report", rnew { exceptionType = ex.GetType().Name });
}
}
Not sure if it works, haven't tested it.
Another approach would be using an exception filter:
public class MyExceptionFilter : FilterAttribute, IExceptionFilter
{
public void OnException(ExceptionContext filterContext)
{
var routeValues = new RouteValueDictionary()
{
{ "controller", "Error" },
{ "action", "Report" }
};
filterContext.Result = new RedirectToRouteResult(routeValues);
filterContext.ExceptionHandled = true;
// Or I can skip the redirection and render a whole new view
//filterContext.Result = new ViewResult()
//{
// ViewName = "Error"
// //..
//};
}
}
Given:
request.UrlReferrer.LocalPath = "/MyApp/MyHome/List";
and I have a Route Mapping that handles this where MyHome is my controller and List is an action that takes a ViewModel. Other variations of this Route include paging and sorting but these are captured by the ViewModel.
My question is this:
How can I use the above URL to generate an instance of the related ViewModel?
EDIT: I have an JQuery Dialog that is adding/updating/deleting an item in a list that is shown by the url in the urlreferrer- the example given is the most basic. When the dialog sends the data to be a/u/d, I want to return the updated body of the list and display that. This information is handled by a different ViewModel than what is instantiated on the POST from the dialog (the url posted to is "/MyApp/MyHome/Edit/True" - for creating a new whatever). This piece follows the standard MVC process and of course works. What I want to do is create a second ViewModel based on the ViewModel for the list action and return this as a partial view containing the updated paged list.
Ok... I think I have this figured out. This is not pretty but it works. I welcome anybody's input to actually feed this through a ModelBinder or any other MVC artifact but here's what I came up with:
First we need to fake a request using the UrlReferrer instead of the actual url being requested:
public class FakeHttpContext : HttpContextBase
{
public FakeHttpContext(HttpContextBase currentContext)
{
_request = new FakeHttpRequest(currentContext.Request);
}
HttpRequestBase _request;
public override HttpRequestBase Request
{
get
{
return _request;
}
}
HttpResponseBase _response = new FakeHttpResponse();
public override HttpResponseBase Response
{
get
{
return _response;
}
}
class FakeHttpRequest : HttpRequestBase
{
HttpRequestBase _request;
public FakeHttpRequest(HttpRequestBase currentRequest)
{
if(currentRequest == null)
throw new ArgumentNullException();
this._request = currentRequest;
}
public override string ApplicationPath
{
get
{
return this._request.ApplicationPath;
}
}
public override string AppRelativeCurrentExecutionFilePath
{
get
{
return "~" + this._request.UrlReferrer.AbsolutePath.Remove(0, this._request.ApplicationPath.Length);
}
}
public override string PathInfo
{
get
{
return this._request.PathInfo;
}
}
}
class FakeHttpResponse : HttpResponseBase
{
}
}
Next, we feed the fake call through the RouteTable to get it broken down. and match up properties to the RouteData.Values.
public static class RouteAndModelBinder
{
public static void BuildViewModel<TViewModel>(ControllerContext context, TViewModel model)
{
FakeHttpContext fake = new FakeHttpContext(context.HttpContext);
RouteData test = RouteTable.Routes.GetRouteData(fake);
PropertyInfo[] properties = typeof(TViewModel).GetProperties();
string value;
foreach(PropertyInfo info in properties)
{
if(test.Values.ContainsKey(info.Name))
{
value = (string)test.Values[info.Name];
if(value == null)
{
continue;
}
if(info.PropertyType.IsGenericType &&
info.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
{
Type[] nullables = info.PropertyType.GetGenericArguments();
if(nullables.Length > 0)
{
Type nullableType = nullables[0];
if(nullableType.BaseType == typeof(Enum))
{
object o = Enum.Parse(nullableType, value);
info.SetValue(model, o, null);
}
else if(nullableType == typeof(Int32))
{
info.SetValue(model, int.Parse(value), null);
}
else
{
info.SetValue(model, Convert.ChangeType(value, info.PropertyType), null);
}
}
}
else
{
if(info.PropertyType.BaseType == typeof(Enum))
{
object o = Enum.Parse(info.PropertyType.BaseType, value);
info.SetValue(model, o, null);
}
else if(info.PropertyType == typeof(Int32))
{
info.SetValue(model, int.Parse(value), null);
}
else
{
info.SetValue(model, value, null);
}
}
}
}
}
}
Again, I welcome anybody's suggestions on how I can do this with already established MVC code (ie, ModelBinders, etc). I took some ideas and probably code from here (for the nullable type) and here.