Last
In This Topic
Function Name |
Last | ||
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Set | ||
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Description |
Map only the last in a sequence of values | ||
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Usage
The Data Mapper Set Last function allows you to map the last in a set of sibling items in your XML source. There are many possible reasons for mapping only the last in a set of data values. For example, you may be subject to storage limitations in your target application, or may be sorting your data and mapping the last in a set of resulting values. To apply the Set last function, use the following process:
Create a new Data Mapper file, dragging your XML data source and targets into the editor area.
For this example we are using clubs_source.xsd, an XML Schema Definition
The following source XML will be used:
| Source XML |
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<sport_clubs> <club> <name>New Town Football Club</name> <member> <active>Yes</active> <member_name>Chris Black</member_name> <member_since>2005</member_since> <won>League 2009</won> <won>Cup 2007</won> </member> <member> <active>Yes</active> <member_name>Jim Thomson</member_name> <member_since>2003</member_since> <won>League 2010</won> </member> <member> <active>No</active> <member_name>Barry Jones</member_name> <member_since>1996</member_since> <won>League 1999</won> <won>Cup 1999</won> <won>League 2000</won> </member> </club> <club> <name>City Netball Team</name> <member> <active>No</active> <member_name>Jacqueline Johnson</member_name> <member_since>1999</member_since> <won>National Championship 2001</won> <won>Regional Championship 2002</won> <won>National Championship 2002</won> </member> <member> <active>Yes</active> <member_name>Joanne Smith</member_name> <member_since>2005</member_since> <won>Regional Championship 2007</won> <won>National championship 2007</won> </member> <member> <active>Yes</active> <member_name>Mary Owens</member_name> <member_since>2007</member_since> <won>National Championship 2008</won> </member> </club> </sport_clubs> |
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For our target schema we will be using clubs_target.xsd
The data models sporting clubs and their members. Some of the elements can appear multiple times.
Let's assume that we want the member from each club that has been their the longest. Here is the Data Mapper with Source and Target imported:
Drag the Set Last function from the Component Palette into the mapping area:
We will use a sort to get the member with the longest time at the club at the top, then we will take only the last entry for each club.
So add a 'Sort' and a 'Last' sub component to the transform.
We can now connect the 'Xml source->member' to the 'Sort' functions 'Nodes' input, notice when you do this the Sort functions output nodes appear.
You can now use the Sort output 'member' to feed into the 'Last' components 'Nodes' input, again the Last functions outputs are created when you do this.
We can now execute the transform by pressing Shift-F5 or the Execute button (
). The transform is applied and the file we selected as output opens in the editor:
| Output XML |
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<clubs> <team t_name="New Town Football Club"> <player p_name="Chris Black" is_active="Yes"> <joined>2005</joined> <title>League 2009</title> <title>Cup 2007</title> </player> </team> <team t_name="City Netball Team"> <player p_name="Mary Owens" is_active="Yes"> <joined>2007</joined> <title>National Championship 2008</title> </player> </team> </clubs> |
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The longest serving player for each team is now shown.
If the Last function receives an empty input sequence, it will output nothing.
See Also