topic Re: Update attributes in FeatureLayer in ArcGIS API for Silverlight Questions

Update attributes in FeatureLayer

S_Dee — Tue, 02 Nov 2010 14:27:43 GMT

I have a featurelayer and want to edit (update) the attributes of the records. How can I do this?
My featurelayer.Graphics is always 0. I can do featurelayer.Graphics.Add(newfeature) and it will add a new feature to my database, no problem there. But how can I retrieve the features, edit them and save them back to the database?
Any help would be appreciated.

Re: Update attributes in FeatureLayer

DanielWalton — Tue, 02 Nov 2010 14:34:06 GMT

If you're using AGS 10, use the EditorWidget.

Re: Update attributes in FeatureLayer

S_Dee — Tue, 02 Nov 2010 14:42:03 GMT

To clarify: I want to edit only the attributes (not geometries, some of my layers don't even have geometries, they are just tables) and I want to do it in code. If somebody has a code example, that would be great.

Re: Update attributes in FeatureLayer

AliMirzabeigi — Sun, 12 Dec 2021 07:22:53 GMT

For a given Graphic object you can set its attributes as easy as the following code:

...
Graphic g = featureLayer.Graphics[idx];     // idx = index in GraphicCollection of FeatureLayer for edit
g.Attributes["ATTRIBUTE_NAME"] = NEW_VALUE;
...

Re: Update attributes in FeatureLayer

S_Dee — Wed, 03 Nov 2010 11:38:17 GMT

I was hoping it would work like that. My problem seems to be a different one. My featureLayer.Graphics.Count == 0 even after initializing the layer. This what I'm trying:

            FeatureLayer fLayer = new FeatureLayer()
            {
                ID = "MyLayer",
                Url = "http://mySercer/ArcGIS/rest/services/CI/FeatureServer/0"
            };
            fLayer.Initialized += new EventHandler<EventArgs>(fLayer_Initialized);
            fLayer.Initialize();

The event handler:

        void fLayer_Initialized(object sender, EventArgs e)
        {
            MessageBox.Show(this.fLayer.Graphics.Count.ToString()); // this is 0
            bool test = fLayer.IsInitialized; // this is true
            Graphic newGraphic = new Graphic();
            fLayer.Graphics.Add(newGraphic); // this works, a new record is added to the database
        }

So, even after initializing the layer, the Graphics collection is empty (but I can add new records). What am I missing?

Re: Update attributes in FeatureLayer

DanielWalton — Wed, 03 Nov 2010 11:50:40 GMT

Instead of calling Initialize() directly, just add the layer to your map control.

MyMap.Layers.Add(fLayer);

Re: Update attributes in FeatureLayer

S_Dee — Wed, 03 Nov 2010 14:52:27 GMT

After adding the FeatureLayer to the map, the Graphics collection is populated after UpdateCompleted fired and I can edit attributes. I can use this as a workaround, but ideally I don't want to add the FeatureLayer to the map, because there's nothing to display in the map.
If I call FeatureLayer.Update() on a FeatureLayer that is not added to the map I get a NullReferenceException, even if it is initialized first.

Re: Update attributes in FeatureLayer

AliMirzabeigi — Sun, 12 Dec 2021 07:22:56 GMT

If you don't want to add the layer to your map you should invoke the Update() method of the FeatureLayer after your layer gets initialized. See the code snippet below:

private void fLayer_Initialized(object sender, EventArgs e)
        {
            fLayer.UpdateCompleted += new EventHandler(fLayer_UpdateCompleted);
            fLayer.Update();
        }
private void fLayer_UpdateCompleted(object sender, EventArgs e)
        {
            MessageBox.Show(this.fLayer.Graphics.Count.ToString()); // this is not zero
        }

Re: Update attributes in FeatureLayer

EduardoMartinez — Thu, 03 May 2012 18:49:17 GMT

This is unresolved? I have looked for the solution to this problem in several posts but i can't find it, what i'm doing wrong? with mode set to snapshot i have no problem, i can add, modify and delete graphics, but when i change to ondemand gives me a NullReferenceException

flProgramas.Url = "http://absoluteurl";
flProgramas.Where = "1=1";
flProgramas.AutoSave = false;
flProgramas.Mode = FeatureLayer.QueryMode.OnDemand;
flProgramas.OutFields = new ESRI.ArcGIS.Client.Tasks.OutFields() { "*" };
flProgramas.Initialized += (s, e) =>
{
                flProgramas.UpdateCompleted += fLayer_UpdateCompleted;
                flProgramas.UpdateFailed += flProgramas_UpdateFailed;
                flProgramas.Update();   <<<<-----------------------------Right here
};
flProgramas.Initialize();
flProgramas.EndSaveEdits += flProgramas_EndSaveEdits;
flProgramas.SaveEditsFailed += flProgramas_SaveEditsFailed;

i'm working with tables, and i need to use ondemand because i have a lot of rows, thanks in advance

Re: Update attributes in FeatureLayer

DanielWalton — Thu, 03 May 2012 18:54:48 GMT

OnDemand makes no since for a layer that isn't in a map. I'm guessing that the null reference occurs when the layer looks for the Map extent to determine the envelope parameter to pass on to the server. If you need to manage the collection size in a disconnected layer, use the Where parameter.