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Subject:
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Joining Nodes (HELP!!)
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Posted By:
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MissHenesy
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Post Date:
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10/12/2006 4:26:03 PM
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Dear People,
Does anyone know how to use XSLT / XPATH to join 2 different sets of nodes and produce results??
For example, below is a source XML file. What I would like to do is:
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Spit out the FOOD_IDs where the associated FOOD_TYPE_ID is equal to "1".
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The format of the xml file below mimics the actual structure of the XML document I have at work (which doesn't deal with anything nearly as interesting as waffles and french toast - wish it did!).
I've been researching XSL and XPATH for a few days now and still have not managed to find a way to do this seemingly simple task.
So - since I'm at wit's end - I'm begging for help!
HELP!
Thank you,
Susan :o)
<breakfast_menu>
<!--***** FOOD *******-->
<food>
<food_id>1</food_id>
<name>Belgian Waffles</name>
<price>$5.95</price>
<description>two of our famous Belgian Waffles with plenty of real maple syrup</description>
<calories>650</calories>
</food>
<food>
<food_id>2</food_id>
<name>Strawberry Belgian Waffles</name>
<price>$7.95</price>
<description>light Belgian waffles covered with strawberries and whipped cream</description>
<calories>900</calories>
</food>
<food>
<food_id>3</food_id>
<name>French Toast</name>
<price>$4.50</price>
<description>thick slices made from our homemade sourdough bread</description>
<calories>600</calories>
</food>
<!--****** FOOD TYPES *******-->
<!-- Food Type 1: WAFFLES -->
<food_type>
<food_type_id>1</food_type_id>
<food_id>1</food_id>
</food_type>
<food_type>
<food_type_id>1</food_type_id>
<food_id>2</food_id>
</food_type>
<food_type>
<food_type_id>1</food_type_id>
<food_id>3</food_id>
</food_type>
<!-- Food Type 2: FRENCH TOAST -->
<food_type>
<food_type_id>2</food_type_id>
<food_id>3</food_id>
</food_type>
</breakfast_menu>
Susan :)
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Reply By:
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mhkay
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Reply Date:
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10/12/2006 5:33:36 PM
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>Spit out the FOOD_IDs where the associated FOOD_TYPE_ID is equal to "1".
In your data a food ID can have more than one associated food type ID.
You don't actually need a join for this, you can write
//food_type[food_type_id=1]/food_id
That will give you duplicates - there is a whole literature on how to eliminate duplicates (search for "XSLT grouping") (it's easy in XPath 2.0 using distinct-values()).
A better use case for a join is to list the food names with food type id = 1, that is
//food[id = //food_type[food_type_id=1]/food_id]/name
But in XSLT you would normally use keys to do this, for readability and for performance.
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference
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Reply By:
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MissHenesy
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Reply Date:
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10/17/2006 5:26:34 PM
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Dear Michael Kay,
Thank you!! I was very close -- turns out I was off by one "/".
I'm glad you responded, because you set me off looking for info about keys and getting distinct values, and I've since learned an arsenal about XSLT/XPATH in the past couple of days. I've refined my original files and hope to get better at this.
Eventually :o).
Much gratitude,
Susan
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