Looking for best practice focused answers here with explanations.
Should the presentation layer of an ASP.Net app catch and handle exceptions thrown from the business layer, or should these be allowed to bubble out, where they can all be logged and handled uniformly in the Global.ascx's Application_Error handler?
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If I am just logging exception details in my web app, do I really need to put in exception handling logic for each tier? Why not just let them all bubble up the stack trace to the global.asax and log them there?
View 5 RepliesI'm trying to handle all my application exceptions inside the global.asax but from some reason it's not firing at all, i never tried to do it before so i guess i'm doing something wrong here...
here is the code inside the default.aspx page that throw the error:
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Just for kicks, how do you say, wire up an ASP button to purposely throw an Application_Error exception in the global.asax file?
lets say you wanted to test the functionality of the error handling and what is doing..and you don't have a real error to do it. what is the easiest way just raise this event?
I am handling errors in Global.asax. When I encounter an error in certain pages, the Application_Error event fires twice. On the second trip, Server.GetLastError() returns null. I have a simple page where I throw an error in page load. When that page throws an error the code below works fine. I also have a more complex page with an update panel and many controls. When that page throws an error Application_Error fires twice. I suspect the update panel but update panels are always suspect, right?
There are no try/catch blocks on any of my pages I'm testing with. Custom errors in web.config is commented out. Note that logging and busywork in the Application_Error event are commented out. I'm pretty much just doing a respone.redirect. The problem with the the event firing twice is that the response.redirect fails with an error msg stating that headers have already been sent (adding Context.ClearError and Response.Clear does nothing to fix that).
I'm trying to use the Global.asax file in the root application of the website to catch requests for pdf files in the root that don't exist any more. I've configured iis to send pdf requests to asp.net. The whole thing works perfectly on development. It also works on the live system with missing .aspx pages, but not .pdf. Instead an "Error Code 64: Host not available". I'm using the Global.asax file to avoid the web.config and child applications (1.1 & 2.0) inheriting settings.
Edit:
I configured IIS to send .pdf requests to asp.net using the Application Configuration dialog on the mappings tab and adding .pdf extension mapped to the aspnet_isapi.dll. "Verify that file exists" is turned off (although I've also tried it turned on).
So I handle all exceptions in my project within my Global.asax page. For example, on a random page I could have:
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So my question is in the Application_Error method, do I need the try/catch block when trying to write to the database? I'm thinking I would in case something goes wrong with the connection, etc. - but is this really necessary? Also, what would I do in the catch block if there is an error? At that point I would be catching the error of logging an error which is confusing in its own right.
I have custom errors set in the web config file as follows:
<customErrors mode="RemoteOnly" defaultRedirect="GenericError.aspx" />
Fine and dandy... I like that mode="RemoteOnly" facilitates development...
For unhandled exceptions, I have in global.asax:
Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
Response.Redirect("GenericError.aspx")
End Sub
However, unhandled exceptions are going to the generic error page instead of the informative yellow screen of death preferred by developers. I can comment out the redirect in global.asax, but then I need to remember to change it for the production environment. Is there a way I can check in Application_Error whether I am remote or not to determine whether to redirect?
I'm using a static Timer in my Global.asax to run a method at regular intervals. When the method throws an exception, my application is stopped. I have used an empty catch to prevent exceptions from stopping the application something like below code. Is there a disadvantage to use such an approach?
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i want to handle browser event in Global.asax. i can handle it in page(aspx) but problem is that, same code i need to repeate on each page. so can i define code only once?
View 3 Repliesi'm using asp.net 2.0.
there's a way to add an handler to manage the session_end event without using the global.asax?
(i can't modify my httpapplication code so i need to add the handler externally to it)
I'm building the standard 3-tier ASP.NET web application but I'm struggling as to where to do certain things - specifically handling exceptions.
I've tried to have a look around on the web for some examples but can't find any which go as far as a whole project showing how everything links together.
In my data-tier I'm connecting to SQL Server and doing some stuff. I know I need to catch exceptions that could be raised as a result but I'm not sure where to do it.
From what I've read I should be doing it in the UI tier but in that case I'm not sure how to ensure that the connection to the database is closed. Is anyone able to clarify how to do this? Also if anyone knows as to where I could find an example 3-tier web application that follows best practices that would be great too.
"I DONOT WANT TO use the default error page tachnique, because i donot want the webpage to redirect!"
yes there is the try and catch
yes there are way to add exception handling mathods overwrite for controls
but what i need is,
it may just be a simple sql command,it may be a control such as formview, it may be a control such as datagrid, whatever it may be, when an illegal entry is done into the table of the database,
"THE BIG ERROR PAGE SHOULD NOT COME!!"
instead
a label at the top of the same page (where the illegal operation is performed) should display the error like
"error caused by "this control" and the error message is "null is not allowed in this field blah blah"
I know there are a few posts on this issue already, however I haven't found the answers I was really looking for.
My situation is like this: I have a DLL project containing my business logic. Then I have a web application that refers to this DLL, and calls a function from it. And I have a global.asax which handles errors on Application_Error
Sample:
// MyWebsite.aspx.cs
using MyBusinessLogic;
protected void Page_Load(object sender, EventArgs e)
{
MyBusinessLogicClass.DoSomething();
}
// global.asax.cs
protected void Application_Error(object sender, EventArgs e)
[Code].....
I have error handling in Application_Error event of globals.asax file. Inside this event, I'm using Response.Redirect(~errorview.aspx) method, for redirection to site which is able to handle errors in user friendly way.
Everything works fine, unless exception is rising in Application_Start event. When error occurs there, my application gets trapped in infinite loop with the Application_Error method hit repeatedly. What is more, the page I'm redirecting to never gets hit. Changing Response.Redirect(~errorview.aspx) method to Response.Redirect(~errorview.aspx, false) changes nothing.
The good news is, when Response.Redirect(~errorview.aspx) has been replaced with Server.Transfer(~errorview.aspx), errorview.aspx page succesfully gets hit.
The side effect now is not loading CSS, and errorview.aspx page looks ugly. What is more, the CSS is not loaded only when exception occurs in Application_Start event. Exceptions thrown from any other place don't make the CSS mess.
How I can handle this problem in correct way, and why the CSS is missing in the one particular situation ? What is the appropriate way of handling errors in my case ?
UPDATE
For CSS loading, I'm using this:
<link href="~/Css/Layout/style.css" type="text/css" rel="stylesheet"
runat="server" ID="_uid" />
error page I'm transfering from: http://localhost/APP/Pages/Module/Pages/ErrorView.aspx
css folder path: http://localhost/APP/Pages/Module/CSS/Layout/style.css
I have the following settings. Asp.net 2.0 / Vs.net 2005 / Web.config -> customErrors mode="on"
<customErrors mode="On" defaultRedirect="~/ErrorPages/Default.aspx">
I am trying to use the Application_Error to redirect the user to a custom error page. I know I could use the web.config to do this, but let's assume for now that this is not a desirable path to take.
Initially, I tried to do a Response.Redirect to perform this, however, there seem to be occasions where the current http context does not define the response object. So, I attempted to perform a check to make sure that the response object is not null prior to attempting the redirection, and if it is not defined, perform a Server.Transfer instead.
What happens is that in most cases, the Redirect causes the browser to some generic "friendlyish" error page rather than the requested error page.
So then I tried using Server.Transfer exclusively, and this worked well for most cases, however, sometimes the transfer didn't seem to take in the browser. Changing it back to a redirect in these cases solved that problem, but reintroduced the issue where the errors previously being captured and transferred now were being redirected.
What I surmised from this is that in certain contexts where the Application_Error method is trapped, it is necessary to use Server.Transfer in redirection, whereas in others, it is necessary to use Response.Redirect. The question then became twofold: (a) When is one necessary and when is the other? and (b) What available information can I poll to tell me when a given condition exists.
After much searching, I cannot find a reasonable answer to this question. So I began to trap errors and examine the HttpContext object for some indicator. One thing that I was looking for is the reason why if even with a defined Response in the current context does a redirect fail. The only thing that stood out is that even though a Response object may exist, the Session data could be absent. I added the case to check whether the Session data was null and perform a Transfer in this case and it
seems to be handling it properly.
I emphasize "seems to be handling it properly" because no documentation I've been able to find confirms either the problem I am having or whether this is an appropriate strategy for solving it.
I guess the question is, am I on the right track here or is the null Session object just a red herring, indicative of nothing relevant. Here's the check I have set up for reference.
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I have an ASP.NET application where i am tracking my applicaion level erros using golabl.asax On_Error method.I will send an email to my id when there is some error happened in the site(ie :" when the application _error being invoked) Now From my global.asax's Application_OnError event, how can i get the URL of the page where this error was raised ?
View 3 RepliesI am categorizing my website page to be defined as Secured & unsecured (ie few page on http & other on https) in Global.asax. Now, Product.aspx page has to be defined as unsecured. But I just couldn't make out how to define this since it is called with a querystring. If I simply define it as "Product.aspx", output is coming incorrect ie I need to define it as "Product.aspx?pid=123". But since there are lot many products, so I couldn't define it like this.
View 2 RepliesI have set up custom error on my server and i'm redirecting to a page as shown below
<customErrors mode="On">
<error statusCode="500" redirect="/servererror/default.aspx" />
</customErrors>
When it gets to the page servererror/default.aspx I need it to send an e-mail to me with the exception.message
Here's what i'm trying but it won't work
Sub Page_load(ByVal sender As Object, ByVal e As EventArgs)
Dim LastError As Exception
Dim ErrMessage As String
LastError = Server.GetLastError()
ErrMessage = LastError.Message
[Code]....
I'm wanting to adjust this code to pull the theme name from a database table, instead of just manually assigning a theme in the file. This way a site administrator can set the theme dynamically. If never done this with a global.asax file, so I'm not sure what the best way is to accomplish it?
Here's the code that needs tweaked:
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The database table could be "ThemeName" with rows ID & Theme. If performing this in the global.asax file will cause any big performance issues.
When i start the application, based on some condition in global.asax page,i wil redirect to login page.If i click the logout button,
there i vil be clear all session value. here i want to initiate new session value like Session["InitialLogin"]="Yes".
How can i get this value in global .asax page. If get that session value [i.e Session["InitialLogin"]="Yes"], i vil redirect to some other page.
I cant able to get session value in global.asax page.i always getting null value.
I have a ASP.NET/C# web application. There is an object instantiated in the Global.asax that I'll call g_objVariable. What I would like to do is reference one of it's properties in the ASP.NET page itself, like this.
The g_objVariable's Prop1 value is: <%=AppNameSpace.Global.g_objVariable.Prop1.ToString()%>
I get it to see the reference, but it keeps telling me that due to it's protection level I can't access it. I have it set to 'internal static'. What would be the least level I could set it to, but still allow the page to access it?
My website needs hit counter. i have created hit count in global.asax page, which works fine. Now i wanted to display hit count in all pages. so, do i have to use mater page or function to all in every page.
View 3 RepliesI know there is a couple answered questions on here regarding "request scoped" globals, but I want to nit-pick on something specifically and maybe squeeze some extra enlightenment out of one or two of you.I have an ASP.NET C# Website and a static Dictionary of objects (loaded from DB once on Application start). Each page request will need to do a lookup in the Dictionary (based on a key derived from the request url/etc) and get the appropriate object.The issue is I'm trying to maximize efficiency by reducing the lookups to the Dictionary per Request. Doing just a single lookup within a Page itself is easy enough and I can pass the object to sub controls, etc too.. but global.asax is separate from the Page and it also needs to use the object (in Application_BeginRequest and Session_Start).
So is doing a Dictionary lookup once in Application_BeginRequest, once (when necessary) in Session_Start and once in the Page negligible speed wise, even if there are many requests coming in every second?I would like it if I could just have a Request scoped global variable that I can easily call upon.. the only one I see available though is HttpContext.Current.Items and that is a Dictionary itself.Am I beingridiculously nit-picky with my concern over efficiency? or will these milliseconds (nanoseconds?) get me in the long run when more and more requests are being made?
PS. I currently only have around 100 objects in the Dictionary although this may increase in the future.