Cool way to get/set processed HTML Markup in filters
Hi,
There was a case where i had to encrypt the HTML output of the GSP before displaying it to user. There are a lot of ways to do it, but i wanted to make is as simple as possible. Hence here is the pattern i used:
Note: This is just an example, you can use this concept to do thousands of cool things, like: pdf export etc..
ON THE GSP
<html>
<head>
<meta name="encrypt" value="true" />
...
</head>
.... misc code
</html>
Here what is did is, i created a GSP and just added a meta property to it saying “encrypt true”.
Now here is the Code for the Grails Filters (See inline comments)
def filters = {
all(controller: '*', action: '*') {
before = {
}
after = { Map model ->
try {
//Get the Site Mesh Page Instance
GSPSitemeshPage sitemeshPage = response?.getContent() as GSPSitemeshPage
//Check if it is actual sitemest page, not just plain rendered content
if (sitemeshPage && sitemeshPage.getPage()) {
//Get the meta property value.
String metaPropValue = sitemeshPage.getProperty("meta.encrypt")
if (metaPropValue && metaPropValue == "true") {
//This is how you can get html contents of head/body after all tags resolved.
String head = new String(sitemeshPage.getHead())
String body = new String(sitemeshPage.getBody())
//Buffer for new body
StreamCharBuffer writer = new StreamCharBuffer()
//Write to buffer new content
writer.getWriter().write(encryptionService.encrypt(body))
sitemeshPage.setBodyBuffer(writer)
}
}
} catch (Throwable ex) {
ex.printStackTrace()
}
}
afterView = { Exception e ->
}
}
}
And hence we have this processed content in response 
Regards
Kushal Likhi
Great Article!
Just for record, this is intelligrape stuff we readers look for, great tips which we can’t find anywhere else.
I will try the pdf export with this, and let you know. Seems promising though.