How to access AS3 URLLoader return data on IOError

问题:

I'm writing an actionscript library for an api. I use a URLLoader object to load data from the api. The problem I'm having is that whenever the api returns an http status in the 400s, actionscript treats this as an io error. This is all find and good, however, it seems like there is no way to access any data that was returned if this is the case. Consequently, any helpful xml about the cause of the error that gets returned is lost. Is there any way around this? It makes the library kind of a pain, if there can't be any useful information for developers when the api returns an error. Thanks for any help!

回答1:

You can't get access to the data in an event of a 400. You can get the status code, however, by adding a listener for the HTTP status event.

If you control the back-end code, there are a couple of workarounds:

One option is to have the backend respond with 200s even in error cases when talking to a flash client, but with a special error code so the client knows that the 200 response is actually an error.

Another option is to set a cookie on the client containing the error message. Flash can't natively access cookies, but you can call out to javascript using ExternalInterface to read the cookie, or optionally the client can do another hit to a special back-end controller that reads the cookie and responds with an error message.