Getting the result of query without using FeatureLayer

AlaeddineSaadaoui — Thu, 31 May 2012 17:11:16 GMT

Hi all,
I have implemented a function to get the result of a query and I have put the following code after defining queryTask and myQuery:
queryTask.execute(myQuery);
var attrs:Object=queryTask.executeLastResult.attributes;
But when I execute this function, attrs is always a Null object. So I am wondering how I can get the result of my query without using the feature layer option because I could not control the order of its execution.
Any help would be appreciated.
Thank you in advance,
Alaeddine Saadaoui.
Rahall Transportation Institute.

Re: Getting the result of query without using FeatureLayer

ThomasMcCracken — Thu, 31 May 2012 19:26:04 GMT

I believe the results of your query are multiple objects so an array would be more appropriate for your variable.

Thomas McCracken
GIS Analyst
Georgia Power Company

Re: Getting the result of query without using FeatureLayer

AlaeddineSaadaoui — Fri, 01 Jun 2012 05:07:33 GMT

Hi Thomas,
My problem is with queryTask.executeLastResult.attributes, it always returns a null object.
Thank you.
Alaeddine Saadaoui.

Re: Getting the result of query without using FeatureLayer

IvanBespalov — Fri, 01 Jun 2012 06:14:14 GMT

working with FeatureLayer

<?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"        xmlns:s="library://ns.adobe.com/flex/spark"        xmlns:mx="library://ns.adobe.com/flex/mx">    <fx:Script>   <![CDATA[    import com.esri.ags.FeatureSet;    import com.esri.ags.Graphic;    import com.esri.ags.events.LayerEvent;    import com.esri.ags.layers.FeatureLayer;    import com.esri.ags.layers.supportClasses.Field;    import com.esri.ags.tasks.supportClasses.Query;        import mx.collections.ArrayCollection;    import mx.controls.Alert;    import mx.rpc.AsyncResponder;    import mx.rpc.Fault;    import mx.utils.StringUtil;        import spark.components.gridClasses.GridColumn;        [Bindable]    private var gridSource:ArrayCollection = new ArrayCollection();        [Bindable]    private var gridColumns:ArrayCollection = new ArrayCollection();        private var queryLayer:FeatureLayer = null;        private function initializeLayer():void    {     queryLayer = new FeatureLayer(txtServiceUrl.text);     queryLayer.mode = FeatureLayer.MODE_ON_DEMAND;     queryLayer.outFields = new Array("*");     queryLayer.addEventListener(LayerEvent.LOAD, onLayerLoaded, false, 0, true);     dispatchEvent(new LayerEvent(LayerEvent.LOAD, queryLayer));    }        protected function onLayerLoaded(event:LayerEvent):void    {     queryLayer.removeEventListener(LayerEvent.LOAD, onLayerLoaded);     txtServiceUrl.editable = false;     executeQuery();    }        protected function onExecuteButtonClick(event:MouseEvent):void    {     if (queryLayer != null && queryLayer.loaded)     {      executeQuery();     }     else      {      initializeLayer();     }    }        private function executeQuery():void    {     var query:Query = new Query();     query.where = txtWhere.text;          var outs:Array = StringUtil.trim(txtOuts.text).split(",");     query.outFields = queryLayer.outFields = outs;          queryLayer.queryFeatures(query, new AsyncResponder(onQueryResult, onQueryFault));    }        protected function onQueryResult(featureSet:FeatureSet, token:Object = null):void    {     gridSource = new ArrayCollection();     lblResultsCount.text = StringUtil.substitute("Found: {0} features.", featureSet.features.length);     for each(var gr:Graphic in featureSet.features)     {      gridSource.addItem(gr.attributes);     }     gridSource.refresh();          gridColumns = new ArrayCollection();     for each (var field:Field in featureSet.fields)     {      var gridColumn:GridColumn = new GridColumn(field.alias);      gridColumns.addItem(gridColumn);     }     gridColumns.refresh();           }        protected function onQueryFault(fault:Fault, token:Object = null):void    {     trace(fault.getStackTrace());     Alert.show("Query faults.", "Error");    }        protected function onGetLastResults(event:MouseEvent):void    {     if (gridSource) // != null     {      var messgae:String = StringUtil.substitute("Last results length is {0}", gridSource.length);      Alert.show(messgae, "Message");     }     else     {      Alert.show("No last results found!", "Warning");     }    }   ]]>  </fx:Script>      <s:Panel width="100%"      title="Query parameters">      <s:VGroup gap="5"        paddingLeft="5"        paddingTop="5"        paddingRight="5"        paddingBottom="5"        width="100%">        <s:HGroup width="100%">          <s:Label text="Url:"         width="150" />          <s:TextInput id="txtServiceUrl"         width="100%"         text="http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5" />         </s:HGroup>        <s:HGroup width="100%">          <s:Label text="Where clause:"         width="150" />          <s:TextInput id="txtWhere"          width="100%"         text="1=1" />         </s:HGroup>        <s:HGroup width="100%">          <s:Label text="Out fields (CSV):"         width="150" />          <s:TextInput id="txtOuts"          width="100%"         text="STATE_NAME,STATE_FIPS,SUB_REGION,STATE_ABBR,POP2000,POP2007" />         </s:HGroup>        <s:HGroup width="100%">          <s:Button label="Execute" click="onExecuteButtonClick(event)" />          <s:Button label="Last result length" click="onGetLastResults(event)" />         </s:HGroup>       </s:VGroup>     </s:Panel>    <s:Panel title="Results"      width="100%"     height="100%">      <s:VGroup gap="5"        paddingLeft="5"        paddingTop="5"        paddingRight="5"        paddingBottom="5"        width="100%"       height="100%">        <s:Label id="lblResultsCount" />        <s:DataGrid width="100%"       height="100%"       dataProvider="{gridSource}"       columns="{gridColumns}"/>       </s:VGroup>     </s:Panel>   </s:Application>

or working without feature layer (using QueryTask)

<?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"        xmlns:s="library://ns.adobe.com/flex/spark"        xmlns:mx="library://ns.adobe.com/flex/mx">    <fx:Script>   <![CDATA[    import com.esri.ags.FeatureSet;    import com.esri.ags.Graphic;    import com.esri.ags.layers.supportClasses.Field;    import com.esri.ags.tasks.QueryTask;    import com.esri.ags.tasks.supportClasses.Query;        import mx.collections.ArrayCollection;    import mx.controls.Alert;    import mx.rpc.AsyncResponder;    import mx.rpc.Fault;    import mx.utils.StringUtil;        import spark.components.gridClasses.GridColumn;        [Bindable]    private var gridSource:ArrayCollection = new ArrayCollection();        [Bindable]    private var gridColumns:ArrayCollection = new ArrayCollection();        private var queryTask:QueryTask;        protected function onExecuteButtonClick(event:MouseEvent):void    {     executeQuery();    }        private function executeQuery():void    {     var query:Query = new Query();     query.where = txtWhere.text;     query.returnGeometry = false;          var outs:Array = StringUtil.trim(txtOuts.text).split(",");     query.outFields = outs;          queryTask = new QueryTask(txtServiceUrl.text);     queryTask.execute(query, new AsyncResponder(onQueryResult, onQueryFault));    }        protected function onQueryResult(featureSet:FeatureSet, token:Object = null):void    {     gridSource = new ArrayCollection();     lblResultsCount.text = StringUtil.substitute("Found: {0} features.", featureSet.features.length);     for each(var gr:Graphic in featureSet.features)     {      gridSource.addItem(gr.attributes);     }     gridSource.refresh();          gridColumns = new ArrayCollection();     for each (var field:Field in featureSet.fields)     {      var gridColumn:GridColumn = new GridColumn(field.alias);      gridColumns.addItem(gridColumn);     }     gridColumns.refresh();           }        protected function onQueryFault(fault:Fault, token:Object = null):void    {     trace(fault.getStackTrace());     Alert.show("Query faults.", "Error");    }        protected function onGetLastResults(event:MouseEvent):void    {     if (queryTask && queryTask.executeLastResult) // != null     {      var results:Array = queryTask.executeLastResult.attributes;      var messgae:String = StringUtil.substitute("Last results length is {0}", results.length);      Alert.show(messgae, "Message");     }     else     {      Alert.show("Query task is null or has no results!", "Warning");     }    }   ]]>  </fx:Script>      <s:Panel width="100%"      title="Query parameters">      <s:VGroup gap="5"        paddingLeft="5"        paddingTop="5"        paddingRight="5"        paddingBottom="5"        width="100%">        <s:HGroup width="100%">          <s:Label text="Url:"         width="150" />          <s:TextInput id="txtServiceUrl"         width="100%"         text="http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5" />         </s:HGroup>        <s:HGroup width="100%">          <s:Label text="Where clause:"         width="150" />          <s:TextInput id="txtWhere"          width="100%"         text="1=1" />         </s:HGroup>        <s:HGroup width="100%">          <s:Label text="Out fields (CSV):"         width="150" />          <s:TextInput id="txtOuts"          width="100%"         text="STATE_NAME,STATE_FIPS,SUB_REGION,STATE_ABBR,POP2000,POP2007" />         </s:HGroup>        <s:HGroup width="100%">          <s:Button label="Execute" click="onExecuteButtonClick(event)" />          <s:Button label="Last result length" click="onGetLastResults(event)" />         </s:HGroup>       </s:VGroup>     </s:Panel>    <s:Panel title="Results"      width="100%"     height="100%">      <s:VGroup gap="5"        paddingLeft="5"        paddingTop="5"        paddingRight="5"        paddingBottom="5"        width="100%"       height="100%">        <s:Label id="lblResultsCount" />        <s:DataGrid width="100%"       height="100%"       dataProvider="{gridSource}"       columns="{gridColumns}"/>       </s:VGroup>     </s:Panel>   </s:Application>

Query execution returns:

query faults (wrong query params, url, ...)

query complete, but no results returned (nothing found ...)

query complete, and results returned

so you must listen/handle query complete/fault events to know "what happens?", to know "where happens?", to know "why queryTask.executeLastResult.attributes is null?"...

good luck

Re: Getting the result of query without using FeatureLayer

AlaeddineSaadaoui — Tue, 05 Jun 2012 12:20:27 GMT

Hi ibespalov,
Thank you very much for your help.
Alaeddine Saadaoui

topic Getting the result of query without using FeatureLayer in ArcGIS API for Flex Questions

Getting the result of query without using FeatureLayer

Re: Getting the result of query without using FeatureLayer

Re: Getting the result of query without using FeatureLayer

Re: Getting the result of query without using FeatureLayer

Re: Getting the result of query without using FeatureLayer