[xquery-talk] Generating an element sequence matching a template

[Howard Katz]

That does indeed work with the given example, but it fails in a slightly
more complex case, one that unfortunately I didn't think to provide. I
showed an example with duplicate entries in the template; I should have
shown one that also has duplicates in the *data*, a not uncommon occurrence.

For example, this solution doesn't work if there are duplicate <e_1> nodes
in the data:

let $template := ( "e_1", "e_2", "e_3", "e_1", "e_4" ) 
let $row-data := ( <e_1>11</e_1>, <e_3>33</e_3>, <e_1>e_11-2</e_1>,
<e_4>44</e_4> )

Saxon reports "A sequence of more than one item is not allowed as the first
argument of string()".

Any thoughts?

Howard

 > -----Original Message-----
 > From: talk-bounces at xquery.com 
 > [mailto:talk-bounces at xquery.com] On Behalf Of Michael Kay
 > Sent: April 25, 2006 11:55 AM
 > To: 'Howard Katz'; talk at xquery.com
 > Subject: RE: [xquery-talk] Generating an element sequence 
 > matching a template
 > 
 > Isn't it simply:
 > 
 > for $t in $template return
 >   element {$t} { string($row-data[local-name()=$t]) }
 > 
 > Michael Kay
 > http://www.saxonica.com/
 > 
 > > -----Original Message-----
 > > From: talk-bounces at xquery.com 
 > > [mailto:talk-bounces at xquery.com] On Behalf Of Howard Katz
 > > Sent: 25 April 2006 19:39
 > > To: talk at xquery.com
 > > Subject: [xquery-talk] Generating an element sequence 
 > > matching a template
 > > 
 > > 
 > > Given a template of element names, I want to be able to write 
 > > an XQuery function that takes that template, as well as a 
 > > sequence of element nodes, and returns a "filled-out" list of 
 > > elements where the template supplies the final length of the 
 > > list and the names of empty elements to add to it if they're 
 > > missing from the data. It's probably easier to provide an 
 > > example than describe it.
 > > 
 > > For example, given the data:
 > > 
 > > let $template := ( "e_1", "e_2", "e_3", "e_1", "e_4" ) let 
 > > $row-data := ( <e_1/>11</e_1>, <e_3>33</e_3>, <e_4>44</e_4> )
 > > 
 > > I want the "fill-row-data( $template as xs:string+, $row-data 
 > > as element()+ )" function to return this sequence:
 > > 
 > > ( <e_1/>11</e_1>, <e_2/>, <e_3>33</e_3>, <e_1/>, <e_4>44</e_4> )
 > > 
 > > The initial $row-data will contain some or all of the 
 > > elements named in the template, and in the same order where 
 > > present. The number of nodes in the final result will be the 
 > > same as the number of names in the template. Where the 
 > > element sequence has nodes corresponding to the template, 
 > > those nodes are left as is. Where nodes that are named in the 
 > > template are missing from the actual data, empty filler nodes 
 > > are generated (eg <e_2/> and <e_1/>.
 > > 
 > > The problem is motivated by a desire to produce an xhtml 
 > > table where the list of <th> headers is fixed, but the actual 
 > > data rows are sparse and heterogenous. I want to be able to 
 > > generate homogenous rows so that the contents of each row 
 > > exactly matches the given header. 
 > > 
 > > Howard
 > > 
 > > _______________________________________________
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 > > http://xquery.com/mailman/listinfo/talk
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