XSLT grouping with filter - xslt

Question

I am trying to do XSLT grouping within a call template while applying a filter. The below code works fine but it is not considering the filter condition and is returning all the nodes . Please help me to understand what I am doing wrong . My understanding is that is that it has something to do with the scope of the below line
<xsl:for-each select="key('ParentName',#ParentName)" >
Here is the xml and xslt .
<?xml version="1.0" encoding="utf-16"?>
<Documentation>
<Consequences>
<Nodes>
<Node1 name ="abc1" ParentName="Group1" IsInternal ="true" />
<Node1 name ="abc2" ParentName="Group2" IsInternal ="true"/>
<Node1 name ="bcd1" ParentName="Group2" IsInternal ="true" />
<Node1 name ="bcd2" ParentName="Group1" IsInternal ="false"/>
<Node1 name ="efg1" ParentName="Group2" IsInternal ="false"/>
<Node1 name ="efg2" ParentName="Group1" IsInternal ="false" />
</Nodes>
</Consequences>
</Documentation>
XSLT : -
<xsl:output method="xml" indent="yes"/>
<xsl:template match="Consequences" >
<xsl:call-template name="Template1">
<xsl:with-param name="NodeList" select="Nodes/Node1[#IsInternal='true']"/>
</xsl:call-template>
</xsl:template>
<xsl:key name="ParentName" match="Node1" use="#ParentName" />
<xsl:template name ="Template1">
<xsl:param name="NodeList" />
<xsl:for-each select="$NodeList[generate-id()=generate-id(key('ParentName',#ParentName)[1])]">
<Group>
<xsl:value-of select="#ParentName" />
<xsl:for-each select="key('ParentName',#ParentName)" >
<SubItems>
<xsl:value-of select="#name" />
</SubItems>
</xsl:for-each>
</Group>
</xsl:for-each>
</xsl:template>

Answer 1

Assuming that you are trying to select only the elements who's #IsInternal='true', instead of simply all of the Node1 elements that have the specified #ParenName.
Your xsl:key is matching on all of the Node1 elements and indexed by the #ParentName value. If you are only using that key to retrieve the elements who's #IsInternal='true', then you can add a predicate filter to the match criteria:
<xsl:key name="ParentName" match="Node1[#IsInternal='true']" use="#ParentName" />
If you need to use that key to lookup Node1 elements by #ParentName in other areas without regard to what the #IsInternal value is, then you could filter the items returned from the key lookup:
<xsl:for-each select="key('ParentName',#ParentName)[#IsInternal='true']" >
<SubItems>
<xsl:value-of select="#name" />
</SubItems>
</xsl:for-each>
You could also define a key that uses the value of both the #ParentName and the #IsInternal values as the key value:
<xsl:key name="ParentName" match="Node1"
use="concat(#ParentName,'-',#IsInternal)" />
and then retrieve them with the same key value:
key('ParentName',concat(#ParentName,'-',#IsInternal))