"count" field is always "1" with custom JavaScript YQL Open Data Table - yql

Question

YQL returns the number of records retrieved in its XML output:
<query xmlns:yahoo="http://www.yahooapis.com/v1/base.rng"
yahoo:count="2" yahoo:created="2012-08-24T14:02:32Z" yahoo:lang="en-US">
<diagnostics>
But I've been experimenting with my own custom Open Data Tables, at least ones which employ an execute block containing JavaScript to create the response, and no matter how I create the response the count field is always set to 1 when I make a query using the table.
I've also dug around in the documentation and can't seem to find anything addressing this.
Is this by design? Is it a bug? Have I missed something obvious?

Answer 1

This is commonly caused by only returning one result, which shouldn't really come as a surprise. The most usual cause of this, from my own experience, is forgetting to specify a suitable itemPath for the <select>.
Take the following examples, and see how the response.object structure and itemPath combine to give the query results.
Without an itemPath
<select itemPath="" produces="XML">
<execute>
<![CDATA[
response.object = <letters>
<letter>A</letter>
<letter>B</letter>
<letter>C</letter>
</letters>
]]>
</execute>
</select>
Produces a query result similar to:
<query xmlns:yahoo="http://www.yahooapis.com/v1/base.rng"
yahoo:count="1" yahoo:created="…" yahoo:lang="en-US">
<results>
<letters>
<letter>A</letter>
<letter>B</letter>
<letter>C</letter>
</letters>
</results>
</query>
With itemPath="letters"
<select itemPath="letters" produces="XML">
…
</select>
Produces a query result identical to the previous result.
<query xmlns:yahoo="http://www.yahooapis.com/v1/base.rng"
yahoo:count="1" yahoo:created="…" yahoo:lang="en-US">
<results>
<letters>
<letter>A</letter>
<letter>B</letter>
<letter>C</letter>
</letters>
</results>
</query>
With itemPath="letters.letter"
<select itemPath="letters.letter" produces="XML">
…
</select>
Note that now, the path now specifies a collection of letter items. This produces a query result similar to:
<query xmlns:yahoo="http://www.yahooapis.com/v1/base.rng"
yahoo:count="3" yahoo:created="…" yahoo:lang="en-US">
<results>
<letter>A</letter>
<letter>B</letter>
<letter>C</letter>
</results>
</query>