topic Re: How to use Layer Definitions in Identify Parameters? in ArcGIS API for Silverlight Questions

How to use Layer Definitions in Identify Parameters?

JoannaLaroussi — Fri, 02 Dec 2011 17:51:54 GMT

I try to set my Identify tool to identify only the results of my query task instead all of them (this includes invisible). Setting LayerOption = LayerOption.visible does not work in my case, because the query task returns one result for polygon feature class and one for points, where the extent of polygons is much bigger than points. I would like to be able identify only these points, which were returned by a query, but all polygons. My guess is I should use Layer Definitions, but I do not know how exactly to do it. I tried something like this:
private void IdentifyStart()
        {
            ESRI.ArcGIS.Client.Tasks.IdentifyParameters identifyParams = new IdentifyParameters()
            {
                Geometry = _clickPont,
                MapExtent = Map.Extent,
                Width = (int)Map.ActualWidth,
                Height = (int)Map.ActualHeight,
                SpatialReference = Map.SpatialReference,
                Tolerance = 10,

IEnumerable < "PreKSitesGraphicsLayer" > IdentifyParameters.LayerDefinitions,
            };

But this is not working. Does someone have idea how to solve it, or can provide me with any code sample? Thank you!

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Mon, 05 Dec 2011 07:05:00 GMT

If you just want to show or hide some layers, you don't need to change the LayerDefinitions.
You can set the LayerIds with the sublayers that you want to show.

Re: How to use Layer Definitions in Identify Parameters?

JoannaLaroussi — Wed, 07 Dec 2011 12:51:07 GMT

If you just want to show or hide some layers, you don't need to change the LayerDefinitions.
You can set the LayerIds with the sublayers that you want to show.

Thank you for your advice. It turned out that the problem was much more complicated and required some changes in the way how layers are displayed and queries are made.

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Sun, 12 Dec 2021 04:16:54 GMT

Thank you for your advice. It turned out that the problem was much more complicated and required some changes in the way how layers are displayed and queries are made.

You can look at the documentation of the ArcGISDynamicMapServiceLayer.
LayerDefinitions for this class is close from the layerDefinitions of an IdentifyTask.

The difference being that you can't set the LayerDefinitions of an IdentifyTask in XAML. You have to do it by code (look at the end of the topic).

In your case it's something like :

 
ESRI.ArcGIS.Client.Tasks.IdentifyParameters identifyParams = new IdentifyParameters()
{
Geometry = _clickPont,
MapExtent = Map.Extent,
Width = (int)Map.ActualWidth,
Height = (int)Map.ActualHeight,
SpatialReference = Map.SpatialReference,
Tolerance = 10,
 
LayerDefinitions = new[]
{
  new LayerDefinition {LayerID = 0, Definition = "Magnitude = 6"},
  new LayerDefinition {LayerID = 1, Definition = "Name = 'Paris'"}
  .........
} 
};

Re: How to use Layer Definitions in Identify Parameters?

JoannaLaroussi — Fri, 09 Dec 2011 12:35:43 GMT

Thanks a lot for a link to documentation �?? it helped me to better understand the entire process.

Re: How to use Layer Definitions in Identify Parameters?

JeffSauder — Wed, 25 Jan 2012 12:47:40 GMT

If you just want to show or hide some layers, you don't need to change the LayerDefinitions.
You can set the LayerIds with the sublayers that you want to show.

When I try to set the LayerIds I get an error that it is read only. Is there any way to set this?

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Wed, 25 Jan 2012 12:58:04 GMT

When I try to set the LayerIds I get an error that it is read only. Is there any way to set this?

LayerIDs is not supposed to be a read-only property.

Code like: myLegend.LayerIDs = new[] {"ID1", "ID2"}; should work.

What is your code when you get this error?

Re: How to use Layer Definitions in Identify Parameters?

JeffSauder — Wed, 25 Jan 2012 13:39:40 GMT

The code that gets the error below:

                ESRI.ArcGIS.Client.Tasks.IdentifyParameters idParams = new IdentifyParameters()
                {
                    Geometry = env,
                    //Tolerance = 3,
                    MapExtent = Gilbert.Extent,
                    Width = (int)Gilbert.ActualWidth,
                    Height = (int)Gilbert.ActualHeight,
                    LayerOption = LayerOption.all,
                    LayerIds = LayerIDList[cboLayerList.SelectedIndex]
                };

I found one answer, as of version 2.2 I have to code it as <IdentifyParameters>.LayerIds.Add(<layerid>);

However, I am having a problem with it, after I set it it does nothing, all layers are still returned.

What I am trying to do is have the user set a combo box with the layer they want to identify, then return only that layer.

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Wed, 25 Jan 2012 14:18:24 GMT

Sorry, my previous answer was about the LayerIds property of the Legend not of the IdentifyParameter.

For IdentifyParameter, LayersIds is a read-only List of int.

So we can't set it but you can modify the list by code such as :
identifyParameter.LayerIds.Add(3);
or
identifyParameter.LayerIds.Clear();

So in your case, I guess it should be something like:
idParams.LayerIds.Add(LayerIDList[cboLayerList.SelectedIndex]);

Re: How to use Layer Definitions in Identify Parameters?

JeffSauder — Wed, 25 Jan 2012 15:03:04 GMT

That is the code that I used, and I don't get an error. However, identify still returns all layers for some reason.

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Wed, 25 Jan 2012 15:08:13 GMT

That is the code that I used, and I don't get an error. However, identify still returns all layers for some reason.

Strange.
Try with LayerOption.visible instead of 'all'.
Nevertheless I thought 'all' option would work as well.

Re: How to use Layer Definitions in Identify Parameters?

JeffSauder — Wed, 25 Jan 2012 15:39:12 GMT

It does the same thing with all visible layers, for some reason will not return just the one layer.

Re: How to use Layer Definitions in Identify Parameters?

DominiqueBroux — Wed, 25 Jan 2012 15:41:43 GMT

That's not normal.

If possible try using fiddler to look at the request sent to the server.

That might give a clue.

Re: How to use Layer Definitions in Identify Parameters?

JeffSauder — Wed, 25 Jan 2012 16:07:25 GMT

This is what fiddler shows being sent to the server:

GET /GilbertGIS/rest/services/GilbertPW/MapServer/identify?geometryType=esriGeometryEnvelope&geometry=%7b%22xmin%22%3a749079.006624349%2c%22ymin%22%3a849040.14211143%2c%22xmax%22%3a749701.296908102%2c%22ymax%22%3a849367.663313405%2c%22spatialReference%22%3a%7b%22wkid%22%3a2868%7d%7d&returnGeometry=true&imageDisplay=1695%2c851%2c96&layers=visible%3a0%2c0%2c1%2c2%2c3%2c4%2c5%2c6%2c7%2c8%2c9%2c10%2c11%2c12%2c13%2c14%2c15%2c16&tolerance=2&mapExtent=745070.147112175%2c845601.169490692%2c756173.115859128%2c851175.580348308&f=json& HTTP/1.1

It looks like after the layers=visible part the 3a0 is layer 0 in the layerid and the 2c parts that follow have each of the 17 layers.

Re: How to use Layer Definitions in Identify Parameters?

BarraLoubna — Wed, 05 Dec 2012 11:49:59 GMT

Hello,

I would like to appear in the Identify combobox, just the layers that are visible in the list of layers.

I tried what you suggested in this post, but it does not work.

code :

...
List<int> visibleLayerList =
dynamicServiceLayer.VisibleLayers != null
? dynamicServiceLayer.VisibleLayers.ToList() : new List<int>();

IdentifyTask identifyTask = new IdentifyTask("http://romulus/ArcGIS/rest/services/Limites_Administratives_Luxembourg/MapServer/");

...

identifyParameters.LayerIds.Add(visibleLayerList[IdentifyComboBox.SelectedIndex]);

Someone can help me?

Thank you.