ColdFusion Quickie - Turning a set of XML nodes into a string.
Yesterday a reader sent me a question concerning XML handling and ColdFusion, and while it was rather simple, I thought others might like to see a quick demo of it as well. Imagine for a minute this simple XML data.
The XML above describes a simple article. You've got a title, an author object, and paragraphs of text each as their own XML node. The reader simply wanted to know how to get those paragraphs into one string variable. You may be tempted to do this:
But doing so returns you one XML node.
One of the oddities of ColdFusion's XML handling is that it treats some things as a singular value and some things like an array. So if I take the same "address" and run arrayLen() on it, like so...
I'll get 4. This is the clue then that tells us to simply loop over them like an array and append each value to a string.
Note that I've also wrapped the values in P tags to help me display it later.
Can't believe how happy I am that CF10 started supporting xpath 2.0.
foo.bar.baz.bobo.wahoo.xmlText
When one goes to access some node in an xml object, coldfusion first has to determine if the root node is a struct or an xml doc. Then, for each successive node, it must compare the next node name with some sort of hash map to identify the next member of the path. Equiv of figuring out that foo.bar is really foo["bar"]. Or possibly depending on the underlying xml classes, figuring out that foo.bar is really foo.getBar() or some other equivelent behind the scenes. This translation takes a little bit of overhead, compounded by each node further down one goes.
Generally, this is trivial and is ignorable under a lot of circumstances as the cost of ease of use versus direct java manipulation.
However, when doing complex pattern matching to identify and collect nodes for work, the above in combination with in-cf logic processing adds up quickly when in comparison to using a java native xpath parser such as xmlSearch provides a bridge to.
Case of proper tool for the job at hand at a given complexity need, much like how ORM is kind of nice, but doesn't fully leverage the power one has of full SQL functionality for complex things.
<cfset s = structNew()>
<cfset s["somekey"] = "somevalue">