How to handle null return from custom HttpHandler in asp.net?

Posted by Campos on Stack Overflow See other posts from Stack Overflow or by Campos
Published on 2010-06-08T17:54:59Z Indexed on 2010/06/08 18:02 UTC
Read the original article Hit count: 223

Filed under:

c#

|

ASP.NET

|

image-manipulation

|

httphandler

|

ashx

I'm using a custom ashx HttpHandler to retrieve gif images from a database and show it on a website - when the image exists, it works great.

However, there are cases when the image will not exist, and I'd like to have the html table holding the image to become invisible so the "image not found" icon is not shown.

But since the HttpHandler is not synchronous, all my attempts checking for image size at Page_Load were frustrated. Any ideas on how this can be accomplished?

© Stack Overflow or respective owner

Related posts about c#

.NET WebRequest.PreAuthenticate not quite what it sounds like

as seen on West-Wind - Search for 'West-Wind'
I’ve run into the problem a few times now: How to pre-authenticate .NET WebRequest calls doing an HTTP call to the server – essentially send authentication credentials on the very first request instead of waiting for a server challenge first? At first glance this sound like it should be easy:… >>> More
HttpWebRequest and Ignoring SSL Certificate Errors

as seen on West-Wind - Search for 'West-Wind'
Man I can't believe this. I'm still mucking around with OFX servers and it drives me absolutely crazy how some these servers are just so unbelievably misconfigured. I've recently hit three different 3 major brokerages which fail HTTP validation with bad or corrupt certificates at least according to… >>> More
The dynamic Type in C# Simplifies COM Member Access from Visual FoxPro

as seen on West-Wind - Search for 'West-Wind'
I’ve written quite a bit about Visual FoxPro interoperating with .NET in the past both for ASP.NET interacting with Visual FoxPro COM objects as well as Visual FoxPro calling into .NET code via COM Interop. COM Interop with Visual FoxPro has a number of problems but one of them at least got a lot… >>> More
Dynamic Type to do away with Reflection

as seen on West-Wind - Search for 'West-Wind'
The dynamic type in C# 4.0 is a welcome addition to the language. One thing I’ve been doing a lot with it is to remove explicit Reflection code that’s often necessary when you ‘dynamically’ need to walk and object hierarchy. In the past I’ve had a number of ReflectionUtils that used string based expressions… >>> More
Finding a Relative Path in .NET

as seen on West-Wind - Search for 'West-Wind'
Here’s a nice and simple path utility that I’ve needed in a number of applications: I need to find a relative path based on a base path. So if I’m working in a folder called c:\temp\templates\ and I want to find a relative path for c:\temp\templates\subdir\test.txt I want to receive back subdir\test… >>> More

Related posts about ASP.NET

Migrating ASP.NET MVC 1.0 applications to ASP.NET MVC 2 RTM

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
Note: ASP.NET MVC 2 RTM isn’t yet released! But this tool will help you get your ASP.NET MVC 1.0 applications ready for when it is! I have updated the MVC App Converter to convert projects from ASP.NET MVC 1.0 to ASP.NET MVC 2 RTM. This should be last the last major change to the MVC App Converter… >>> More
April 14th Links: ASP.NET, ASP.NET MVC, ASP.NET Web API and Visual Studio

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
Here is the latest in my link-listing blog series: ASP.NET Easily overlooked features in VS 11 Express for Web: Good post by Scott Hanselman that highlights a bunch of easily overlooked improvements that are coming to VS 11 (and specifically the free express editions) for web development: unit… >>> More
Use ASP.NET 4 Browser Definitions with ASP.NET 3.5

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
We updated the browser definitions files included with ASP.NET 4 to include information on recent browsers and devices such as Google Chrome and the iPhone. You can use these browser definition files with earlier versions of ASP.NET such as ASP.NET 3 Read More......(read more) >>> More
ASP.NET webforms + ASP.NET Ajax versus ASP.NET MVC and Ajax framework freedom

as seen on Stack Overflow - Search for 'Stack Overflow'
If given the choice, which path would you take? ASP.NET Webforms + ASP.NET AJAX or ASP.NET MVC + JavaScript Framework of your Choice Are there any limitations that ASP.NET Webforms / ASP.NET AJAX has vis-a-vis MVC? >>> More
ASP.NET MVC 2 Released

as seen on ASP.net Weblogs - Search for 'ASP.net Weblogs'
I’m happy to announce that the final release of ASP.NET MVC 2 is now available for VS 2008/Visual Web Developer 2008 Express with ASP.NET 3.5. You can download and install it from the following locations: Download ASP.NET MVC 2 using the Microsoft Web Platform Installer Download… >>> More