Thanks, it works (RE: [xsl] Sort>Filter/Modify whatever...)

["Manos Batsis" <m dot batsis at bsnet dot gr>]

Jeni,

Thanks! You forced me to understand keys, something I was after for two
months but had no time for (or so I thought).

Kindest regards,

Manos

> -----Original Message-----
> From: Jeni Tennison [mailto:jeni@jenitennison.com] 
> Sent: Friday, December 14, 2001 3:12 PM
> To: Manos Batsis
> Cc: xsl-list@lists.mulberrytech.com
> Subject: Re: [xsl] Sort>Filter/Modify whatever...
> 
> 
> Hi Manos,
> 
> > As I have thought of it, for each element of name=*, I have to check
> > for elements with the same name, then look within their permission
> > attr to pic the one I want or build one if multiple same_name
> > elements exist with a combination of persmission attrs that should
> > become one complex one.
> 
> I'd approach this as a grouping problem, and use the old Muenchian
> Method. Index all the USER elements by their name attribute using a
> key:
> 
> <xsl:key name="users" match="USER" use="@name" />
> 
> Then you can just pick on the USER elements that are the first with
> that name within the document using:
> 
> <xsl:template match="USERS">
>   <USERS>
>     <xsl:apply-templates
>       select="USER[generate-id() = generate-id(key('users', 
> @name)[1])]" />
>   </USERS>
> </xsl:template>
> 
> Have a template that matches USER elements. You know that this
> template will only be applied to the first USER with a particular
> @name, so you can safely create a USER element with that name
> attribute:
> 
> <xsl:template match="USER">
>   <USER name="{@name}">
>     ...
>   </USER>
> </xsl:template>
> 
> When creating the permission attribute, you need to work out whether
> there are any other USER elements in the document with the same name.
> You can find out using the key again, retrieving all the USER elements
> that have the name of the current USER:
> 
> <xsl:template match="USER">
>   <USER name="{@name}">
>     <xsl:attribute name="permission">
>       <xsl:variable name="permissions"
>                     select="key('users', @name)/@permission" />
>       ...
>     </xsl:attribute>
>   </USER>
> </xsl:template>
> 
> Now you need to sort out your priorities and work out what new
> permission attribute to add. It might look something like:
> 
> <xsl:template match="USER">
>   <USER name="{@name}">
>     <xsl:attribute name="permission">
>       <xsl:variable name="permissions"
>                     select="key('users', @name)/@permission" />
>       <xsl:choose>
>         <!-- if any of the permissions is 'none', then it should be
>             'none' -->
>         <xsl:when test="$permissions = 'none'">none</xsl:when>
>         <!-- if there's a 'read' permission and a 'write' permission
>              then it should be 'read-write' -->
>         <xsl:when test="$permissions = 'read' and
>                         $permissions = 'write'">read-write</xsl:when>
>         ...
>         <!-- if we get here, just use the first permission -->
>         <xsl:otherwise>
>           <xsl:value-of select="$permissions" />
>         </xsl:otherwise>
>       </xsl:choose>
>     </xsl:attribute>
>   </USER>
> </xsl:template>
> 
> I hope that helps,
> 
> Jeni
> 
> ---
> Jeni Tennison
> http://www.jenitennison.com/
> 
> 

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