Archives
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Unable to generate code for a value of type... Can you tell what's wrong?
I recently got this error when trying to run a WebControl that had a property that is a collection of objects that have a property that uses a type converter to convert its string persistence format to its real type (still following me?). Here's what the persisted format looks like:
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Fun with callbacks, Part 2: The RefreshPanel
ASP.NET 2.0 makes it easier to develop Web applications that do out-of band calls, as we saw in the previous post. But one thing I noticed is that most applications will really just want to refresh and update some part of the page without touching the rest of it. In this case, the second client-side script, the one that receives the results from the callback and updates the page is always the same, something like element.innerHTML = response;.
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Fun with callbacks Part 1: What's in the ASP.NET box?
There's a lot of buzz currently around Web out-of-band calls, aka XmlHttp, aka AJAX (the guy who coined this term must be some kind of marketing genius for imposing a new acronym for a technique that's been used for many years). It seems like the world is suddenly discovering that it is possible to get an update to a Web page from the server without posting back. Many techniques have been used for that purpose: Java applets (ASP classic was using this technique in Remote Scripting more than eight years ago), hidden frames and iframes, dynamically reloaded <script> elements and even reloading transparent images using cookies as the information transportation vessel. But the technique really became more than just a clever hack when Microsoft introduced the XmlHttpRequest object in Internet Explorer 5. The goal was to populate Xml data islands without sending back the whole page, hence the Xml prefix, but today it doesn't have much to do with Xml any more as the data that's transferred is most of the time not Xml. Client-side Xml never really happened.
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Open() late, Close() early
One of the most common mistakes Web developers do is try to be smart about database connection management. Connections are expensive resources, and it seems like it would make a lot of sense to store an open connection, say, in a Session or Application variable, for later re-use, so that next time you need it, it's already there and ready to use.
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No April Fool's jokes this year :(
Yesterday, all bloggers here at Microsoft received a memo from Steve Ballmer asking us not to do any April Fool's jokes on our blogs. Here's a citation from this memo:"This kind of joke can affect the image of the company negatively and spread false information. We'll have to be very strict on enforcing this policy and any employee who chooses not to obey this simple rule will have to face sanctions up to and including termination of their employment."That's really sad, I had a few good ones that I had been preparing. Oh well.Update: of course, this was written on April 1st, so none of this is true. SteveB never wrote such a memo.