Summary Sorting and Grouping Elements

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Chapter 7. Combining XML Documents

One of XSLTs most powerful features is the document function. document lets you use part of an XML document identified with an XPath expression, of course as a URI. In other words, you can look in a document, use parts of that document as URLs or filenames, open and parse those files, then perform stylesheet functions on the combination of all those documents. In this chapter, well cover the document function in all its glory.

7.1 Overview

The document function is very useful for defining views of multiple XML documents. In this chapter, well use XML-tagged purchase orders that look like this: purchase-order id=38292 customer id=4738 level=Platinum address type=business name titleMr.title first-nameChester Hasbrouckfirst-name last-nameFrisbylast-name name street1234 Main Streetstreet citySheboygancity stateWIstate zip48392zip address address type=ship-to customer items item part_no=28392-33-TT nameTurnip Twaddlername qty3qty price9.95price item item part_no=28813-70-PG namePrawn Goadername qty1qty price18.95price item items purchase-order If we had a few dozen documents like this, we might want to view the collection of purchase orders in a number of ways. We could view them sorted or even grouped by customer, by part number, by the amount of the total order, by the state to which they were shipped, etc. One way to do this would be to write code that worked directly with the Document Object Model. We could parse each document, retrieve its DOM tree, then use DOM functions to order and group the various DOM trees, display certain parts of the DOM trees, etc. Because this is an XSLT book, though, you probably wont be surprised to learn that XSLT provides a function to handle most of the heavy lifting for us.

7.2 The document Function

Well start with a couple of simple examples that use the document function. Well assume that we have several purchase orders and that we want to combine them into a single report document. One thing we can do is create a master document that references all the purchase orders we want to include in the report. Heres what that master document might look like: report titlePurchase Orderstitle po filename=po38292.xml page 121 po filename=po38293.xml po filename=po38294.xml po filename=po38295.xml report Well fill in the details of our stylesheet as we go along, but heres what the shell of our stylesheet looks like: xsl:template match= xsl:for-each select=reportpo xsl:apply-templates select=documentfilename xsl:for-each xsl:template In this template, we use the filename attribute as the argument to the document function. The simplest thing we can do is open each purchase order, then write its details to the output stream. Heres a stylesheet that does this: ?xml version=1.0?-- xsl:stylesheet version=1.0 xmlns:xsl=http:www.w3.org1999XSLTransform xsl:output method=html indent=no xsl:strip-space elements= xsl:template match= html head titlexsl:value-of select=reporttitletitle head body xsl:for-each select=reportpo xsl:apply-templates select=documentfilenamepurchase-order xsl:for-each body html xsl:template xsl:template match=purchase-order h1 xsl:value-of select=customeraddress[type=business]nametitle xsl:text xsl:text xsl:value-of select=customeraddress[type=business]namefirst-name xsl:text xsl:text xsl:value-of select=customeraddress[type=business]namelast-name h1 p xsl:textOrdered on xsl:text xsl:value-of select=datemonth xsl:textxsl:text xsl:value-of select=dateday xsl:textxsl:text xsl:value-of select=dateyear p h2Items:h2 table width=100 border=1 cols=55 15 15 15 tr bgcolor=lightgreen thItemth thQuantityth thPrice Eachth thTotalth tr xsl:for-each select=itemsitem tr xsl:attribute name=bgcolor xsl:choose xsl:when test=position mod 2 xsl:textwhitexsl:text xsl:when xsl:otherwise xsl:textlightgreenxsl:text xsl:otherwise