How do I access the results of querytask.execute. Why do they show as undefined yet I can see them in the object?

JamesHone1

HI I am using queryTask to query a feature layer, if I log the resulting object I can see my features in there.

But when I attempt to access the features in the object I get undefined yet I can access other parts of the object just fine, I just cant get to the results.

		_onDrawComplete<SPAN class="punctuation token">:</SPAN> <SPAN class="keyword token">function</SPAN><SPAN class="punctuation token">(</SPAN>graphic<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
			<SPAN class="keyword token">var</SPAN> geometry <SPAN class="operator token">=</SPAN> graphic<SPAN class="punctuation token">.</SPAN>geometry<SPAN class="punctuation token">;</SPAN>
			<SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">.</SPAN>drawBox<SPAN class="punctuation token">.</SPAN><SPAN class="token function">deactivate</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

			query <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Query</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
			query<SPAN class="punctuation token">.</SPAN>geometry <SPAN class="operator token">=</SPAN> geometry<SPAN class="punctuation token">;</SPAN>
			query<SPAN class="punctuation token">.</SPAN>spatialRelationship <SPAN class="operator token">=</SPAN> <SPAN class="string token">'esriSpatialRelIntersects'</SPAN><SPAN class="punctuation token">;</SPAN>
			query<SPAN class="punctuation token">.</SPAN>returnGeometry <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">true</SPAN><SPAN class="punctuation token">;</SPAN>

			queryTask <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Querytask</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">.</SPAN>featureURLs<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

			<SPAN class="keyword token">var</SPAN> qresults <SPAN class="operator token">=</SPAN> queryTask<SPAN class="punctuation token">.</SPAN><SPAN class="token function">execute</SPAN><SPAN class="punctuation token">(</SPAN>query<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

			console<SPAN class="punctuation token">.</SPAN><SPAN class="token function">log</SPAN><SPAN class="punctuation token">(</SPAN>qresults<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
			console<SPAN class="punctuation token">.</SPAN><SPAN class="token function">log</SPAN><SPAN class="punctuation token">(</SPAN>qresults<SPAN class="punctuation token">.</SPAN>fired<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
			console<SPAN class="punctuation token">.</SPAN><SPAN class="token function">log</SPAN><SPAN class="punctuation token">(</SPAN>qresults<SPAN class="punctuation token">.</SPAN>results<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

As you can see from my log below, when I log qresults it has contains results with values in it, it even has my features stored in the features array in results[0]['features'].

If I try to log qresults.fired I get the value, but if I try to log qresults.results I get undefined even though I can see that it is defined in the previous log of qresults.

Can someone explain why I am seeing results as undefined directly after seeing it with values in it?

Cheers

Jim

RobertScheitlin__GISP

James,

  You have not defined a callback function for the results of the execute.

queryTask<SPAN class="punctuation token">.</SPAN><SPAN class="token function">execute</SPAN><SPAN class="punctuation token">(</SPAN>query<SPAN class="punctuation token">,</SPAN> lang<SPAN class="punctuation token">.</SPAN><SPAN class="token function">hitch</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="keyword token">function</SPAN><SPAN class="punctuation token">(</SPAN>results<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">{</SPAN>
  <SPAN class="comment token">//now you have access to the query results.</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

The reason is a queryTask returns a deferred and the execute is an asynchronous process, so you have to wait for the deferred to resolve before you have access to the results. In my above code it will not get to the function portion until the deferred is resolved.