Brief of The <xsl:key> element:
It has 3 attributes name=name of the key, match=pattern or the node where the key is applicable, use= it is an expression, which is used to arrive at the value of the key for each of the nodes specified in the match attribute. <xsl:key> element must be a child of <xsl:stylesheet/>.
Syntax:
<xsl:key match="/xsdLocal: ListOfOrder/xsdLocal:Order/xsdLocal:ListOfOrderItem/xsdLocal:OrderItem" use="xsdLocal:ShippableFlag" name="TestKey"/>
This is the syntax of how to define a key. Here “TestKey” will applicable to node “OrderItem” and “ShippableFlag” element is value of the key for each of the nodes.
Key ( ) function:
Returns a node-set from the document, using the index specified by an <xsl: key> element.
Syntax:
key(string, object), here string=name of the key and object=condition or string to search for.
<xsl:for-each select="key('TestKey','Y')"/>
Grouping with key( ) & count( ):
<xsl: value-of select="count (key ('TestKey','Y'))"/> this will return the total number of “ShippableFlag” element matched by the key () function.
Grouping with Union & count & key:
If you want to get a list (without repeats) of the repeated IDs using the key () method, then you can use the usual:
Example document:
<ListOfOrder>
<Order>
<ListOfOrderItem>
<OrderItem>
<VolumeUpsellMessage>A</VolumeUpsellMessage>
<ShippableFlag>N</ShippableFlag>
</OrderItem>
<OrderItem>
<VolumeUpsellMessage>B</VolumeUpsellMessage>
<ShippableFlag>Y</ShippableFlag>
</OrderItem>
<OrderItem>
<VolumeUpsellMessage>C</VolumeUpsellMessage>
<ShippableFlag>N</ShippableFlag>
</OrderItem>
<OrderItem>
<VolumeUpsellMessage>D</VolumeUpsellMessage>
<ShippableFlag>Y</ShippableFlag>
</OrderItem>
<OrderItem>
<VolumeUpsellMessage>E</VolumeUpsellMessage>
<ShippableFlag>Y</ShippableFlag>
</OrderItem>
<OrderItem>
<VolumeUpsellMessage>F</VolumeUpsellMessage>
<ShippableFlag>N</ShippableFlag>
</OrderItem>
</ListOfOrderItem>
</Order>
</ListOfOrder>
Case 1: If we want the union of current node & 2nd element from the node set returned by key( ), then code will be like this :-
<xsl:for-each select="/xsdLocal:ListOfOrder/xsdLocal:Order/xsdLocal:ListOfOrderItem/xsdLocal:OrderItem">
<ns0:result>
<xsl:value-of select="count(.|key('TestKey',xsdLocal:ShippableFlag)[2])"/>
</ns0:result>
</ns0:result>
<ns0:result2>
<xsl:value-of select="xsdLocal:ShippableFlag"/>
</ns0:result2>
<ns0:result1>
<xsl:value-of select="xsdLocal:VolumeUpsellMessage"/>
</ns0:result1>
</xsl:for-each>
Target –xml will be like this:-
<ns0:XSL_keyPOCProcessResponse xmlns:ns0="http://xmlns.oracle.com/XSL_keyPOC">
<ns0:result>2</ns0:result>
<ns0:result2>N</ns0:result2>
<ns0:result1>A</ns0:result1>
<ns0:result>2</ns0:result>
<ns0:result2>Y</ns0:result2>
<ns0:result1>B</ns0:result1>
<ns0:result>1</ns0:result>
<ns0:result2>N</ns0:result2>
<ns0:result1>C</ns0:result1>
<ns0:result>1</ns0:result>
<ns0:result2>Y</ns0:result2>
<ns0:result1>D</ns0:result1>
<ns0:result>2</ns0:result>
<ns0:result2>Y</ns0:result2>
<ns0:result1>E</ns0:result1>
<ns0:result>2</ns0:result>
<ns0:result2>N</ns0:result2>
<ns0:result1>F</ns0:result1>
</ns0:XSL_keyPOCProcessResponse>
Case 2: In this case key('TestKey',xsdLocal:ShippableFlag)[2] will return 2nd element of node set by key( ) so that element C(ShippableFlag=N) and D (ShippableFlag=Y). Then count(.|key('TestKey',xsdLocal:ShippableFlag)[2])=1 means it will return those elements whose union with C , D is equals to 1.
A | C=2, B | D=2, C | C=1, D | D=1, E | C=2, F | C=2 so it will return only C | C, D | D.
Code fragment:
<xsl:for-each select="/xsdLocal:ListOfOrder/xsdLocal:Order/xsdLocal:ListOfOrderItem/xsdLocal:OrderItem[count(.|key('TestKey',xsdLocal:ShippableFlag)[2])=1]">
<ns0:result2>
<xsl:value-of select="xsdLocal:ShippableFlag"/>
</ns0:result2>
<ns0:result1>
<xsl:value-of select="xsdLocal:VolumeUpsellMessage"/>
</ns0:result1>
</xsl:for-each>
Target-xml:-
<ns0:XSL_keyPOCProcessResponse xmlns:ns0="http://xmlns.oracle.com/XSL_keyPOC">
<ns0:result2>N</ns0:result2>
<ns0:result1>C</ns0:result1>
<ns0:result2>Y</ns0:result2>
<ns0:result1>D</ns0:result1>
</ns0:XSL_keyPOCProcessResponse>
