How to append node to an existing file

geek.shrek · January 10th, 2010, 12:31 PM

Hi,

I'm using XSLT 2.0.

I would like to append a node to an existing file, but I do not want to create another new file.

for example,
FILE1

Code:

<?xml version="1.0" encoding="UTF-8"?>
<Book version="1.1" Publisher="Wrox">
    <BookDetails NbrOfPages="2" Name="Novel 123">
        <Binding Name="DEF HELLO2" from="1" to="2"/>
        <Page Position="1" Name="page 2"/>
        <Page Position="2" Name="page 3"/>
    </BookDetails>
</Book>

current node

Code:

        <Page Position="1" Name="page 11"/>
        <Paper Position="2" Name="page 12"/>
        <Page Position="3" Name="page 13"/>
        <Page Position="4" Name="page 14"/>    
        <Page Position="5" Name="page 15"/>

result FILE1

Code:

<?xml version="1.0" encoding="UTF-8"?>
<Book version="1.1" Publisher="Wrox">
    <BookDetails NbrOfPages="7" Name="Novel 123">
        <Binding Name="DEF HELLO2" from="1" to="2"/>
        <Page Position="1" Name="page 2"/>
        <Page Position="2" Name="page 3"/>
        <Page Position="3" Name="page 11"/>
        <Paper Position="4" Name="page 12"/>
        <Page Position="5" Name="page 13"/>
        <Page Position="6" Name="page 14"/>    
        <Page Position="7" Name="page 15"/> 
    </BookDetails>
</Book>

My code snippet

Code:

...

<xsl:when test="doc-available('file1.xml')">                         
     <!-- file exist then append to file -->
     <xsl:variable name="curfile" select="document('file1.xml')"/>
         <xsl:result-document href="'file1.xml'"> 
             <Book>                             
             <xsl:attribute name="Version" select="../../../Book/@Version"/> 
             <xsl:attribute name="Provider" select="../../../Book/@Publisher"/> 
             <BookDetails NbrOfPages="{xs:integer($curfile/Book/BookDetails/@NbrOfPages)+xs:integer(current()/@from)-xs:integer(current()/@to)+1}" Name="{$curfile/Book/BookDetails/@Name}"> 
                   <xsl:copy-of select="$curfile/Book/BookDetail/(Paper|Page)"/>
                   <xsl:copy-of select="../(Paper|Page)[@Position=xs:integer(current()/@from) to xs:integer(current()/@to)]"/>
             </BookDetails>
       </xsl:element> 
    </xsl:result-document>
</xsl:when>
...

When I tried to write to the same file, of course I will have error "Cannot write to the URI that has already been read".

So how can I write to an existing file and append my new nodes?

Another question is when I appending to a new file I would like to change the "position" accordingly. So if the existing last position is 2 then when I appending the next position will be 3. Any idea how can I do this?

Thanks,

Martin Honnen · January 10th, 2010, 12:42 PM

I don't think you can read from and write to the same file in one transformation step. You will need to create a result file that is different from the input file and then use tools outside of XSLT to overwrite the input file.

geek.shrek · January 10th, 2010, 01:27 PM

Thanks :)

I'm using java to transform the XSLT. Can XSLT return the transformed result back into Java?

Martin Honnen · January 10th, 2010, 01:38 PM

I don't quite understand what you are asking. Saxon is implemented in Java and certainly exposes an API to Java programmers so that you can use Saxon in your Java applications. Michael Kay is better qualified than I to tell how to use it.
You could start by reading http://www.saxonica.com/documentatio...embedding.html

mhkay · January 10th, 2010, 02:08 PM

You could write the result to a file and (if the transformation is successful) rename the file with the name of the original input. Or you could sent the result to a StringWriter (in effect, buffering it in memory), and then (again, only if successful) write the contents of the StringWriter to the file from your Java application.