Get file size from media folder in Umbraco using XSLT - xslt

Question

Below is a part of my Umbraco xslt where I am outputting a PDF file link and the size of the file. The problem I am having, is targetting the size attribute of the media file. The size attribute has the alias of umbracoBytes.
I just seem to not be able to target this.
So all I am outputting at the moment is the link to open the PDF, but not the file size.
Anyone who can help would be greatly appreciated. Thanks.
<td>
<xsl:if test="document= ''">
<xsl:value-of select="#nodeName"/>
</xsl:if>
<xsl:if test="document != ''">
<a target="_blank">
<xsl:attribute name="href">
<xsl:value-of select="umbraco.library:GetMedia(document, 'false')/umbracoFile"/>
</xsl:attribute>
<xsl:value-of select="#nodeName"/>
<xsl:variable name="size" select="data [#alias = 'umbracoBytes']" />
<xsl:variable name="sizeAndSuffix">
<xsl:choose>
<xsl:when test="$size >= 1073741824">
<xsl:value-of select="format-number($size div 1073741824,'#,###')"/>
<xsl:text>GB</xsl:text>
</xsl:when>
<xsl:when test="$size >= 1048576">
<xsl:value-of select="format-number($size div 1048576,'#,###')"/>
<xsl:text>MB</xsl:text>
</xsl:when>
<xsl:when test="$size >= 1024">
<xsl:value-of select="format-number($size div 1024,'#,###')"/>
<xsl:text>KB</xsl:text>
</xsl:when>
<xsl:when test="$size > 0 and $size < 1024">
<xsl:value-of select="format-number($size div 0,'#,###')"/>
<xsl:text>Bytes</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>0 Bytes</xsl:text>
</xsl:otherwise>
</xsl:choose>
</xsl:variable>
</a>
</xsl:if>
</td>

Answer 1

The problem (I think) is that because you didn't prepend your $size variable select attribute with any target, so by default it uses $currentPage or the current value in a loop iteration.
Try assigning the GetMedia statement to a variable and then get the data from that. Your code appears to have syntax used in different versions of Umbraco, so I can't quite tell which one you're using. Different versions of Umbraco use different underlying XML structure.
If using < Umbraco 4.5.1
<xsl:variable name="myDocument" select="umbraco.library:GetMedia(document, 'false')" />
<a target="_blank">
<xsl:attribute name="href">
<xsl:value-of select="$myDocument/data[#alias='umbracoFile']"/>
</xsl:attribute>
...
<xsl:variable name="size" select="$myDocument/data [#alias = 'umbracoBytes']" />
...
</a>
If using >= Umbraco 4.5.1
<xsl:variable name="myDocument" select="umbraco.library:GetMedia(document, 'false')" />
<a target="_blank">
<xsl:attribute name="href">
<xsl:value-of select="$myDocument/umbracoFile"/>
</xsl:attribute>
...
<xsl:variable name="size" select="$myDocument/umbracoBytes" />
...
</a>

Answer 2

I managed to work it out.
I removed the wrapping variable and created a variable named size which selects the alias UmbracoBytes (the file size)
I then pass the variable through the choose function and this outputs the correct size extension.
Thanks for all your suggestions I really appreciate that!
<xsl:variable name="size" select="umbraco.library:GetMedia(document, 'false')/umbracoBytes"/>
<xsl:choose>
<xsl:when test="$size >= 1073741824">
<xsl:value-of select="format-number($size div 1073741824,'#,###')"/>
<xsl:text>GB</xsl:text>
</xsl:when>
<xsl:when test="$size >= 1048576">
<xsl:value-of select="format-number($size div 1048576,'#,###')"/>
<xsl:text>MB</xsl:text>
</xsl:when>
<xsl:when test="$size >= 1024">
<xsl:value-of select="format-number($size div 1024,'#,###')"/>
<xsl:text>KB</xsl:text>
</xsl:when>
<xsl:when test="$size > 0 and $size < 1024">
<xsl:value-of select="format-number($size div 0,'#,###')"/>
<xsl:text>Bytes</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>0 Bytes</xsl:text>
</xsl:otherwise>
</xsl:choose>