Generating Web Content from Query Results - MySQL

Database Reference

In-Depth Information

The cache-control headers suppress caching for links to banner.py that occur over the

course of successive page requests. Another complication occurs if multiple links to the

script occur within the same page. The following page illustrates what happens:

<html>

<head><title> Banner Ad Test Page 2 </title></head>

<body>

<p> You should see two images below this paragraph,

and they probably will be the same. </p>

<p> You should see two images below this paragraph,

and they probably will be different. </p>

</body>

</html>

The first pair of links to banner.py are identical. What you'll probably find when you

request this page is that your browser notices that fact, sends only a single request to

the web server, and uses the image that is returned where both links appear in the page.

As a result, the first pair of images displayed in the page will be identical. The second

pair of links to banner.py show how to solve this problem. The links include some extra

fluff at the end of the URLs that make them look different. banner.py doesn't use that

information at all, but making the links look different fools the browser into sending

two image requests. The result is that the second pair of images differ from each other,

unless banner.py happens to randomly select the same image both times.

19.9. Serving Query Results for Download

Problem

You want to send database information to a browser for downloading rather than for

display.

Solution

Unfortunately, there's no good way to force a download. A browser processes informa‐

tion sent to it according to the Content-Type: header value, and if it has a handler for

that value, it treats the information accordingly. However, you may be able to trick the

browser by using a “generic” content type for which it's unlikely to have a handler.

MySQL

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