Business validations are implemented by throwing CustomeException(key) such that user will be displayed error messages when something goes wrong.
I have to forward to input jsp (like struts) when business exception raised, to correct the user actions then continue with application.
we have custom HandlerExceptionResolverImpl to handle the all exceptions at once place. when exception raised then we don't know the input page.
How to do this in spring4 like struts ?
Please suggest the way how to accomplish this?
Thanks
Dhorrairaajj
base requirement is explained in this
I have solved this, all controllers should extends CustomeWebReq Class, which has getter method to get the input page like String getInputPage(String path). Controllers are responsible to return the input page based on the servlet path argument. getInputPage(string path) method will be invoked from HandlerExceptionMapping where exceptions are handling.
Thanks
Dhorrairaajj
Related
Is that a good practice to throw exception from controller?
For instance we may throw IllegalStateException from some controller's method if Request hasn't some attribute.
Also for instance we may throw IllegalArgumentException from some controller's method if Request's parameter is not in appropriate format/range.
No, I don't think so. Who will handle it? The client. What does handling it mean? Exceptions won't tell them what to do. Better to change the UI to instruct them on what do to next. You see this in every decent web UI that you use: the text box is highlighted and you're told what the proper range is. What kind of experience would seeing a stack trace be?
So the controller should catch all exceptions and change the display accordingly.
I don't think it is a good idea to throw such exception to end user. Instead you may alert end user a meaningful error message which use can easily understand what is wrong.
So, here's the rundown...
I've got a master layout page for my MVC 4 app that has some dynamic information and needs to be strongly typed to a specific domain entity to get that information. To keep my files cleaner, I've extracted out the typed fields to a partial view.
To grab the entity I need and map it to the partial's view-model, I have a LayoutController with an action that returns a Task<PartialViewResult>. This action uses a service layer to make an async call out to a Web API project, awaiting the entity. It massages that entity into the view-model and then returns PartialView("_LayoutPartial", viewModel).
From within the _Layout page, the partial is called via:
#{Html.RenderAction("LayoutInfo", "Layout", new { /*entity primary key*/ });}
I've stepped through the code and it does indeed get the correct entity back, but then after returning the partial view task, I get everybody's favorite Server Error page with the following error:
HttpServerUtility.Execute blocked while waiting for an asynchronous operation to complete.
I've done some Googling and SO searching and have no idea what this actually means. Am I thinking through this correctly?
That error message means that you're trying to invoke (and wait on!) an asynchronous method from within a synchronous method. In your specific case, the synchronous method is HtmlHelper.RenderAction, and the asynchronous method is your Task-returning action method. The reason the error occurs is that the point of writing an asynchronous Task-returning method is presumably to avoid blocking a thread, but RenderAction can't return until the Task is complete, so RenderAction ends up blocking while waiting for the operation to finish.
One option is to make the method that RenderAction calls synchronous instead of asynchronous, keeping in mind that this will continue to block the original thread. Another option is to populate the layout data asynchronously from within the original action method, then to pass that via ViewData to the layout page.
I'm using Elmah with ASP.NET and wondering how I would add custom data, such as a session variable, to an unhandled exception email.
I've tried several handlers in the Global.asax file but can't seem to find the right one.
For this, I'd think you would need to modify the Elmah source and recompile. It shouldn't be too difficult to achieve. If you have a look in the constructor of the Elmah.Error class, the HttpContext is passed in, from which you should be able to get the info you need, e.g. Session, Form variables etc. You could add custom fields to the Elmah.Error class for this data
I think the Elmah.ErrorMailHtmlFormatter class is where the email is constructed using a HtmlTextWriter, and here you could insert code in the RenderSummary() method to include the custom fields you added to Elmah.Error.
I know it may be a pain to start working with source, but personally I think it's the cleanest way as there currently is no facility for report/email templates, and it's better that bolting on something to change the output after it has been generated.
Andrew's answer helped a lot, thanks. I ended up doing the following:
Added a OnBuilding event to the ErrorMail http module. The event args for this event have a NameValueCollection property.
I handled the OnBuilding event in global.asax.
Since HttpModules don't always have access to sessionstate, esp. if the exception occurs before the session is loaded, I copied the data i wanted reported into the HttpApplication cache(indexed by sessionid).
When an exception occurs I grab the data i want out of the application cache via the sessionid stored in the request(specifically, in the cookie). I generate a NameValueCollection from this data and send it back to the httpmodule via the OnBuilding args.
The data is then rendered to email similarly to how the server variables section is rendered.
Suppose I have a button in an aspx page that performs a save of the form data to the database. In the associated event handler, before sending the updates, I read something from a webservice, operation that might result in an exception. In case of an error I want to have an adequate message displayed on the page, and all the data in the form preserved. How can I achieve this? Also, all my pages inherit from a basepage, so I would like, if possible to have all the error handling code in the base class. I do not want, if possible, to surround any web service call with try-catch blocks, I would in case of any unhandled exception to call some method automatically, something like Page_error, but still preserve the data in my forms.
You can easily put a method that manages the display message (maybe setting the text of some errorMessageLabel) in a superclass called from any derived class (if you wanna use inheritance to setup a template for your pages) if an exception is thrown (you can put the call to the superclas method in a catch block if there's actually an exception being thrown or you can manage this manually if the webservice is unavailable depending on your programming style).
As far as preserving the data presented, if viewstate is on and you are not populating your page dynamically then you're ok - if not, you need to explicitly save state information in viewState or session entries and retrieve them back if something goes wrong.
This bit really depends on how your page is actually implemented.
I am using methods with the Attribute [WebMethod] in my aspx pages. I don't use any asp.net ajax but jQuery to call these methods and return objects in JSON. This all works fine.
Next I added an authorization check inside the webMethod, if the current user doesn't have access to the feature I need to let the calling JavaScript know.
So I am throwing an AccessViolationException exception which can then be parsed by the OnError callback function in JavaScript. This works too but the exception includes the full StackTrace and I don't want to make this available to the calling client.
What other ways I could use to return an "Access Denied" to the client when the WebMethod returns a business object?
I'm using ASP.Net 3.5SP1 and jQuery 1.32
You can also add a:
customErrors mode="On"/
in your web.config, this will cut away the stack trace and leave you only the exception message
Why propagate errors through the wire? why not use an error response ?
Just wrap your object in a response object wich can contain an error code for status and an error message to present to users.
As suggested by NunFur I changed my approach and rather than throwing an error, I return a 'richer' object.
There are at least two options, the first one would be to encapsulate my business object into a response object with some status properties. I tried this but it makes the JSON more complicated.
So rather than adding a new object I added two properties to my business object, something like ServiceStatus and ServiceMessage. By default these are 200 and '', but can be set by the WebMethod code if anything goes wrong (no access, proper error). In this case they business object will be 'empty' (no data). The JavaScript code then first checks for the ServiceStatus and reacts appropriately.
I add the two fields to all my objects that are returned by WebMethods, even a simple string. They have to implement an Interface with those two properties.
Now I have complete control over that goes over the wire in case something unexpected is happening.
Thanks for the input
I save exceptions for when things go really wrong. (e.g. can't connect to the database)
Either return nothing (null/nill/whatever), or return a false bool value.
Sorry that I don't have a better answer than that...I'll have to keep looking myself.
You could look at SoapException: http://msdn.microsoft.com/en-us/library/system.web.services.protocols.soapexception(VS.71).aspx
I'm just not sure, if it will work when it is called from JavaScript. Espeially if it's called with a get-request.
BTW AccessViolationException is to my best knowlegde ment to be thrown when the application is accessing memory it has no access to.
/Asger