change some attribute values using xsl

[Hemal Pandya]

Hello,

I am hoping this is a simple question with a straightforward solution.
I do not understand xsl much, so I apologize in advance if I am asking
a stupid question.

Is it possible to write an xsl that changes some attributes when
applied to an xml document, while preserving rest of it. Is it possible
to write this xsl independently of the structure of the xml document
itself, and only depend on the expression that identifies the attribute
and the value to assign to this attribute ?

For example, I am looking for the xsl document that will do the
following when applies to any xml document:

1. Replace the value of attribute password anywhere it appears in the
xml document with the string '***'
2. Replace the value of attribute password in the element User as above
3. Replace the value of attribute password by prepending and appending
the string 'AAA' to it.

I will really appreciate if someone can provide a sample for this.
Thanks in advance,

- hemal

[p.lepin]

Hemal Pandya wrote:

Is it possible to write an xsl that changes some
attributes when applied to an xml document, while
preserving rest of it.

There's a very basic (and absolutely essential) technique
called 'identity transformation'. The following template
matches and copies all the nodes and attributes
recursively:

<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>

If you need to exclude some nodes from the identity
transformation, you create exclusion templates.

Is it possible to write this xsl independently of the
structure of the xml document itself,

Of course not, you must possess some knowledge about the
structure of the document in question to do anything
non-trivial with it.

and only depend on the expression that identifies the
attribute and the value to assign to this attribute ?

That *is* knowledge about the structure of the document.

1. Replace the value of attribute password anywhere it
appears in the xml document with the string '***'

<xsl:template match="@password">
<xsl:attribute name="password">
<xsl:text>***</xsl:text>
</xsl:attribute>
</xsl:template>

2. Replace the value of attribute password in the element
User as above

<xsl:template match="@password[parent::User]">
<xsl:attribute name="password">
<xsl:text>***</xsl:text>
</xsl:attribute>
</xsl:template>

3. Replace the value of attribute password by prepending
and appending the string 'AAA' to it.

<xsl:template match="@password[parent::User]">
<xsl:attribute name="password">
<xsl:value-of select="concat('AAA',.,'AAA')"/>
</xsl:attribute>
</xsl:template>

I would strongly recommend reading a decent XPath/XSLT
tutorial. You'll learn everything about stuff like this,
and more.

--
Pavel Lepin

[Hemal Pandya]

Thanks for your helpful response Pavel.

Pavel Lepin wrote:

Hemal Pandya wrote:

Is it possible to write an xsl that changes some
attributes when applied to an xml document, while
preserving rest of it.

There's a very basic (and absolutely essential) technique
called 'identity transformation'.

I googled for 'xsl identity transformation' and came across
http://www.dpawson.co.uk/xsl/sect2/i....html#d5687e43. After
reading that I think I understand most of what you suggest.

[....]

I would strongly recommend reading a decent XPath/XSLT
tutorial. You'll learn everything about stuff like this,
and more.

The reason I am interested in this is to change one of the files in the
project that comes from version control. So far I have been changing it
by hand but realized I can perhaps use xsl. I know I aught to read up
but I was hoping the problem is simple enough that I can use some magic
words.

Unfortunately, I realized too late that the example I gave is not quite
similar to the document I am working with. The document I am working
with has the following structure:

<group name="user">
<property name="password" value="none"/>
</group>

Now, I need to modify the value attribute or all property elements
contained in group user that have name=password. I could go as far as
the following for my exclusion template:

<xsl:template match="//group[@name='user']/property[@name='password']">

But I am not able to figure out what goes inside. I am thinking
whatever I put inside will replace the entire property element; what I
need is preserve all of the element except for the value attribute. I
can imagine that it will again be the same principle of identity
conversion with exclusion but can't quite figure it out with my
seat-of-pants approach.

Can you please explain how I would do that?

Thanks,

- hemal

>
--
Pavel Lepin

[p.lepin]

Hemal Pandya wrote:

Pavel Lepin wrote:

Hemal Pandya wrote:

Is it possible to write an xsl that changes some
attributes when applied to an xml document, while
preserving rest of it.

There's a very basic (and absolutely essential)
technique called 'identity transformation'.

I googled for 'xsl identity transformation' and came
across
http://www.dpawson.co.uk/xsl/sect2/i....html#d5687e43
After reading that I think I understand most of what you
suggest.

By the way, that's a part of an *excellent* (if somewhat
poorly organized) XSL FAQ. Most of it is probably
irrelevant to your present woes, but it's definitely worth
reading if you intend to start studying XSLT seriously.

I would strongly recommend reading a decent XPath/XSLT
tutorial. You'll learn everything about stuff like
this, and more.

I know I aught to read up but I was hoping the problem is
simple enough that I can use some magic words.

You're probably not interested in my preachings, but I can
tell you from painful personal experiences that it's always
best to understand the magic you're invoking (if you can
afford it time- and cost-wise).

<group name="user">
<property name="password" value="none"/>
</group>

<xsl:template
match="//group[@name='user']/property[@name='password']">

You're almost there. Indeed, it is workable as is, but
that's a somewhat inelegant solution. Since you need to
change just the value attribute, *match* just the value
attribute:

<xsl:template
match=
"
group[@name='user']/property[@name='password']/@value
">
<xsl:attribute name="value">
<xsl:value-of select="concat('AAA',.,'AAA')"/>
</xsl:attribute>
</xsl:template>

--
Pavel Lepin

[Hemal Pandya]

Pavel Lepin wrote:
[....]

Thanks a ton Pavel. I got it working. I do realize I should study it if
I want to do anything serious, but with your kind help I am in good
shape for now.

Best regards.

- hemal