Re: [xsl] Re: Re-arranging an XML file

Subject: Re: [xsl] Re: Re-arranging an XML file
From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>
Date: Wed, 21 Jan 2009 10:17:16 -0500

At 06:22 AM 1/21/2009, you wrote:
As I mentioned in an earlier post: I'm new to XSL (I've got about 3
hours experience) and am still trying to get my head around it, I have
an XSL file that outputs in CSV format, but when I tried applying it
to the script you sent (below) everything falls down.

Welcome to XSL!

This is indeed a long way from COBOL. You are probably best off thinking of it as a different kind of thing entirely. XSLT is to COBOL as automotive engineering is to wheelwrighting. Don't take this as a slight against COBOL: automobiles need wheels too. (Also, wheels are useful for many things besides automobiles.) It's just that automotive engineering assumes that the principles of wheel design are well understood, and indeed that there is an entire industry (an entire *tire* industry) we can rely on to give us wheels for our automobiles any time we need them.

 There are a few
things I don't understand:
- how can I output in CSV format?

CSV is a special kind of plain text output. In XSLT, when you ask "how can I output X"?, you need to keep in mind that any kind of output presumes two things, the logical and the "physical" (keeping in mind that as long as we're talking about bits on a disk, "physical" is itself questionable). That is, it's a question both about the organization of the output, and the physical form the output takes.

If you're talking about a CSV file on your disk, that's a physical form. To manage this side of the question, XSLT relies on external programs, called serializers (since they take tree-organized XSLT/XPath strucures and sequence their information into streams of characters written to files). Most XSLT processors come with one or more serializers. You need a serializer to write plain text, since it won't have to write any tagging (XML, HTML or what have you) based on the structures it sees in your XSLT results.

Commonly this can be done from your stylesheet using a top-level element:

<xsl:output method="text"/>

which tells the XSLT system to take care of it ("serialize this a plain text, please").

... and then it's only a matter of getting your commas (or other delimiters) in the right place in your CSV (and managing any issues related to that, such as escaping commas in your data. Since this has to do with the organization or arrangement of your data (comma characters being used to organize the data internally), this job will be done by your XSLT proper.

- how do I remove the "<AddedAlbums> tag?
- how can I include (for example) "LastChangedBy" labeling it
something else? (eg "User")

These are really basic questions. Would you mind us referring you to some of the excellent available literature to explain it? You might appreciate one of the starter-level books by Jeni Tennison (she has volumes to cover both XSLT 1.0 and 2.0).

An example would be appreciated.

Here's an example:

<xsl:template match="AddedAlbums">
  <xsl:text>, </xsl:text>

A stylesheet containing this template, assuming no other templates interfere with it, will result in output in which the "AddedAlbums" tags are removed, the data between those tags (the contents of the AddedAlbums elements) are processed (they will probably come through depending on what other templates are doing), and a comma is added after every bit of content that had been an 'AddedAlbums' element.

Notice that there is a *big* difference between removing AddedAlbums *tags* and removing the entire element (which in the XML includes its contents as well as its tags). You asked about removing the tags, so I'm assuming the content is still wanted.


<xsl:template match="LastChangedBy">
  <xsl:text>User: </xsl:text>
  <xsl:text>, </xsl:text>

This does almost the same thing, removing the LastChangedBy tags, allowing the content to be processed, but prefixing it with the text "User: ", while also appending a comma.

I hope this helps. But I really think you need to dig into a good book. The way XSLT works is just not something you could guess based on what was possible twenty years ago....


====================================================================== Wendell Piez mailto:wapiez@xxxxxxxxxxxxxxxx Mulberry Technologies, Inc. 17 West Jefferson Street Direct Phone: 301/315-9635 Suite 207 Phone: 301/315-9631 Rockville, MD 20850 Fax: 301/315-8285 ---------------------------------------------------------------------- Mulberry Technologies: A Consultancy Specializing in SGML and XML ======================================================================

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