topic Can spatial query be used in multi-layers query? in ArcGIS API for Silverlight Questions

Can spatial query be used in multi-layers query?

DanDong — Mon, 08 Nov 2010 17:50:39 GMT

Hi all,

Right now I can do spatial query in one map layer. I have a question about whether I can use spatial query on six map layers. The process is when I draw a polygon, this polygon will cut six layers, each layer will return one column of attributes (like layer1 return the county name, layer2 return the population, layer3...)

in ESRI demo, it design layer 5 is the target layer:
QueryTask queryTask = new QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/" + "Demographics/ESRI_Census_USA/MapServer/5");

Can i design other layers as the target layers? If so, what should I do? Thanks for all of you.

Re: Can spatial query be used in multi-layers query?

JenniferNery — Mon, 08 Nov 2010 19:13:48 GMT

In this example: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Identify

Query is performed on the map service itself, which can contain several sub layers. Is this what you need?

Re: Can spatial query be used in multi-layers query?

DanDong — Mon, 08 Nov 2010 22:23:30 GMT

In this example: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Identify

Query is performed on the map service itself, which can contain several sub layers. Is this what you need?

Thanks Jennifer, Identify really can solve this question. In addition, can I use a loop in spatial query to do the query task on six layers?

Re: Can spatial query be used in multi-layers query?

JenniferNery — Mon, 08 Nov 2010 22:29:33 GMT

You cannot do Async calls in one iteration. You need to make one Async call at a time, after the previous Async call has returned.

Re: Can spatial query be used in multi-layers query?

DanDong — Mon, 08 Nov 2010 22:36:09 GMT

You cannot do Async calls in one iteration. You need to make one Async call at a time, after the previous Async call has returned.

Do you mean this sentence?
queryTask.ExecuteAsync(query)

Re: Can spatial query be used in multi-layers query?

JenniferNery — Mon, 08 Nov 2010 23:20:30 GMT

Yes, that is correct.

Re: Can spatial query be used in multi-layers query?

DanDong — Mon, 08 Nov 2010 23:47:45 GMT

Yes, that is correct.

So badically, I should make a loop for querytask, each time in the loop, just one queryTask.ExecuteAsync(query) was executed. Am I thinking in the correct way?

Re: Can spatial query be used in multi-layers query?

JenniferNery — Sat, 11 Dec 2021 10:28:12 GMT

What I mean to say is that you sure can make multiple queries but keep in mind that you cannot make multiple asynchronous calls sequentially, you need to wait for one to complete before you can call another.

In other words, this would fail:

   identifyTask.ExecuteAsync(identifyParams1);
   identifyTask.ExecuteAsync(identifyParams2);

So for example you have a list of url's to query on, you need to keep track on what has been queried and what has not been queried yet. After the QueryTask ExecultCompleted fires, that is the only time you can call another query.

Re: Can spatial query be used in multi-layers query?

DanDong — Sat, 11 Dec 2021 10:28:14 GMT

What I mean to say is that you sure can make multiple queries but keep in mind that you cannot make multiple asynchronous calls sequentially, you need to wait for one to complete before you can call another.

In other words, this would fail:
   identifyTask.ExecuteAsync(identifyParams1);
   identifyTask.ExecuteAsync(identifyParams2);
So for example you have a list of url's to query on, you need to keep track on what has been queried and what has not been queried yet. After the QueryTask ExecultCompleted fires, that is the only time you can call another query.

Thank you Jennifer! Yeah, I see that 🙂

Then can i use a switch for this, like those below. k is the Id of the layer, say if k=0, give the url of layers.ElementAt(0) to querytask. Then do the query and return different attribute field, for k=0, return "TRS" field, display them in the featuregrid. After this query completed, in the loop, k will be 1, and in the switch, give the url of layers.ElementAt(1) to querytask.

Am I right? Or I make a mistake again 🙂


private void SpatialQuery(object sender, RoutedEventArgs e)
        {
                   
            for (int j = 0; j < 2; j++)
            {

                spatialQ(j);
            }
        }

private void spatialQ(int k)
        {
           
            switch (k)
            {
                
                case 0:
                    
                    QueryTask queryTask = new QueryTask((layers.ElementAt(0) as FeatureLayer).Url);
                    queryTask.ExecuteCompleted += QueryTask_ExecuteCompleted;
                    MessageBox.Show("k="+ k);
                    queryTask.Failed += QueryTask_Failed;
                    Query query = new ESRI.ArcGIS.Client.Tasks.Query();
                    query.OutFields.AddRange(new string[] { "TRS" });
                    ESRI.ArcGIS.Client.Geometry.Polygon queryGeometry = new ESRI.ArcGIS.Client.Geometry.Polygon();
                    queryGeometry.Rings.Add(pPointCollection);
                    query.Geometry = queryGeometry;
                    query.ReturnGeometry = true;
                    queryTask.ExecuteAsync(query);
                    break;

                case 1:
                    
                    QueryTask queryTask1 = new QueryTask((layers.ElementAt(1) as FeatureLayer).Url);
                    queryTask1.ExecuteCompleted += QueryTask_ExecuteCompleted1;
                    MessageBox.Show("k="+ k);
                    queryTask1.Failed += QueryTask_Failed;
                    Query query1 = new ESRI.ArcGIS.Client.Tasks.Query();
                    QueryDetailsDataGrid.DataContext = "null";
                    //query1.OutFields.AddRange(new string[] { "NAME_CNTY" });
                    ESRI.ArcGIS.Client.Geometry.Polygon queryGeometry1 = new ESRI.ArcGIS.Client.Geometry.Polygon();
                    queryGeometry1.Rings.Add(pPointCollection);
                    query1.Geometry = queryGeometry1;
                    query1.ReturnGeometry = true;
                    queryTask1.ExecuteAsync(query1);
                    break;
            }
        }

Re: Can spatial query be used in multi-layers query?

JenniferNery — Tue, 09 Nov 2010 20:24:51 GMT

The best way to know if it works is to try your code 😛

But one thing noticeable here is that you are still calling ExecuteAsync() successively without knowing if the first one has completed or still in process. The next ExecuteAsync() call must be done after the first one is completed (in the ExecuteCompleted eventhandler).

Try out your current code and you should see a run-time error. It's best to see the error to understand what's going on 🙂

Re: Can spatial query be used in multi-layers query?

BrandonCales — Tue, 15 Feb 2011 22:25:36 GMT

Did anyone get this working....I'm trying to do the similar.

Re: Can spatial query be used in multi-layers query?

DanDong — Mon, 21 Feb 2011 18:44:42 GMT

Did anyone get this working....I'm trying to do the similar.

Yes, spatial query can be used in multiple layers. But since it is an asynchronous call, in the end I use a mutex lock to make multiple layers queried sequentially.

Re: Can spatial query be used in multi-layers query?

BrandonCales — Sat, 11 Dec 2021 10:28:17 GMT

I apologize....mutex?

I have it almost working where my initial search_executecompleted then calls search2, however within each I have "ParcelSearch_TaskResultsDataGrid.ItemsSource = featureSet.Features;" which the 2nd is overwriting the 1st.

I have read that pushing my features to a collection then to the datagrid may work, I just am unable to find some reference or code for "collection".

Here is my full code:

private void Execute_ParcelSearch_Click(object sender, RoutedEventArgs e)
        {
            GraphicsLayer ParcelSearch_GraphicsLayer = MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer;
            ParcelSearch_GraphicsLayer.ClearGraphics();

            ParcelSearch_TaskResultsDataGrid.ItemsSource = null;
            ParcelSearch_TaskResultsPanel.Visibility = Visibility.Collapsed;

            if (ParcelSearch_tabControl != null)
            {
                TabControl tb = ParcelSearch_tabControl as TabControl; if (tb.SelectedIndex > -1)
                {
                    ParcelSearch_tab = (tb.SelectedItem as TabItem).Name;
                }

                if (ParcelSearch_tab == "ParcelSearch_tabAPN" && (txtAPN.Text.Length < 4 || txtStNumber.Text == null))
                {
                    MessageBox.Show("You must enter atleast 4 numbers");
                }
                else
                {
                    QueryTask ParcelSearch = new QueryTask("http://{SERVER}/ArcGIS/rest/services/GISPRD_Main/MapServer/79");
                    ParcelSearch.ExecuteCompleted += ParcelSearch_ExecuteCompleted;
                    ParcelSearch.Failed += ParcelSearch_Failed;

                    Query query = new Query();
                    query.ReturnGeometry = true;
                    query.OutSpatialReference = MyMap.SpatialReference;

                    query.OutFields.Add("*");

                    if (ParcelSearch_tab == "ParcelSearch_tabAPN")
                    {
                        query.Where = "APN LIKE '" + txtAPN.Text + "%'";
                    }
                    else if (ParcelSearch_tab == "ParcelSearch_tabAddr")
                    {
                        query.Where = "STNUMBER LIKE '" + txtStNumber.Text + "%' AND STNAME LIKE '" + txtStName.Text + "%' AND STSUFFIX LIKE '" + txtStSuffix.Text + "%'";
                    }

                    ParcelSearch.ExecuteAsync(query);

                    //ParcelSearch_TaskResultsPanel.Visibility = Visibility.Visible;
                }
            }
            else
            {
                MessageBox.Show("You must specify an APN, Address, or Owner to search for");
            }

        }

        private void ParcelSearch2(object sender, RoutedEventArgs e)
        {
            GraphicsLayer ParcelSearch_GraphicsLayer = MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer;

            if (ParcelSearch_tabControl != null)
            {
                TabControl tb = ParcelSearch_tabControl as TabControl; if (tb.SelectedIndex > -1)
                {
                    ParcelSearch_tab = (tb.SelectedItem as TabItem).Name;
                }

                if (ParcelSearch_tab == "ParcelSearch_tabAPN" && (txtAPN.Text.Length < 4 || txtStNumber.Text == null))
                {
                    MessageBox.Show("You must enter atleast 4 numbers");
                }
                else
                {

                    QueryTask ParcelSearch2 = new QueryTask("http://{SERVER}/ArcGIS/rest/services/GISPRD_Main/MapServer/80");
                    ParcelSearch2.ExecuteCompleted += ParcelSearch2_ExecuteCompleted;
                    ParcelSearch2.Failed += ParcelSearch2_Failed;

                    Query query = new Query();
                    query.ReturnGeometry = true;
                    query.OutSpatialReference = MyMap.SpatialReference;

                    query.OutFields.Add("*");

                    if (ParcelSearch_tab == "ParcelSearch_tabAPN")
                    {
                        query.Where = "APN LIKE '" + txtAPN.Text + "%'";
                    }
                    else if (ParcelSearch_tab == "ParcelSearch_tabAddr")
                    {
                        query.Where = "STNUMBER LIKE '" + txtStNumber.Text + "%' AND STNAME LIKE '" + txtStName.Text + "%' AND STSUFFIX LIKE '" + txtStSuffix.Text + "%'";
                    }

                    ParcelSearch2.ExecuteAsync(query);

                    //ParcelSearch_TaskResultsPanel.Visibility = Visibility.Visible;
                }
            }
            else
            {
                MessageBox.Show("You must specify an APN, Address, or Owner to search for");
            }

        }


        private void ParcelSearch_ExecuteCompleted(object sender, ESRI.ArcGIS.Client.Tasks.QueryEventArgs args)
        {
            GraphicsLayer ParcelSearch_GraphicsLayer = MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer;
            ParcelSearch_GraphicsLayer.ClearGraphics();

            FeatureSet featureSet = args.FeatureSet;
               if (featureSet.Features.Count > 0)
            {
                ParcelSearch_TaskResultsDataGrid.ItemsSource = featureSet.Features;

                foreach (Graphic resultFeature in featureSet.Features)
                {
                    resultFeature.Symbol = DefaultFillSymbol;
                    ParcelSearch_GraphicsLayer.Graphics.Add(resultFeature);
                }

                
            }
            else
            {
                //MessageBox.Show("No features found");
            }
            ParcelSearch2(sender, null);
        }

        private void ParcelSearch2_ExecuteCompleted(object sender, ESRI.ArcGIS.Client.Tasks.QueryEventArgs args)
        {

           GraphicsLayer ParcelSearch_GraphicsLayer = MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer;
           
 FeatureSet featureSet = args.FeatureSet;
            if (featureSet.Features.Count > 0)
            {
                ParcelSearch_TaskResultsDataGrid.ItemsSource = featureSet.Features;

                // Add results to map
                foreach (Graphic resultFeature in featureSet.Features)
                {
                    resultFeature.Symbol = DefaultFillSymbol;
                    ParcelSearch_GraphicsLayer.Graphics.Add(resultFeature);
                    
                }

            }
            else
            {
                //MessageBox.Show("No features found");
            }

            ZoomToGraphicsLayer(MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer);

            ParcelSearch_TaskResultsPanel.Visibility = Visibility.Visible;
        }


        private void ParcelSearch_TaskResultsDataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            // Highlight the graphic feature associated with the selected rows
            DataGrid dataGrid = sender as DataGrid;

            int selectedIndex = dataGrid.SelectedIndex;
            if (selectedIndex > -1)
            {
                GraphicsLayer ParcelSearch_GraphicsLayer = MyMap.Layers["ParcelSearch_GraphicsLayer"] as GraphicsLayer;

                ParcelSearch_GraphicsLayer.ClearGraphics();


                foreach (Graphic resultFeature in ParcelSearch_TaskResultsDataGrid.SelectedItems)
                {
                    resultFeature.Symbol = DefaultFillSymbol;
                    ParcelSearch_GraphicsLayer.Graphics.Add(resultFeature);
                }
            }
        }

Re: Can spatial query be used in multi-layers query?

BrandonCales — Wed, 23 Feb 2011 16:24:17 GMT

Resolved....

I passed my features to a global featureset, then at the send of my 2nd ExecuteCompleted i populate the datagrid.