[GIS] Creating report from selected features in ArcMap using AddIn and C#

add-inarcgis-10.0arcobjectsc

I am new to ArcGIS and I am trying to create an Add-In button which can

  1. figure out which polygons are selected and
  2. query the selected polygons to generate a report on the underlying metadata (similar to the Identify tool).

I had a look at this article, which helped with finding the selected feature layer, but I haven't been able to progress much further.

At the moment all I have is a one-liner. Here is some pseudo code of what I would like to do:

var featureLayer = ArcMap.Document.CurrentContentsView.SelectedItem as IFeatureLayer;
var selectedFeatures = featureLayer.SelectedFeatures;

// A list to contain the info available in Identify tool (not sure what this is called)
var featuresAttributes = new List<FeatureAttributes>();

// For each selected polygon
foreach(var feature in selectedFeatures)
    featuresAttributes.Add(feature.Attributes);

// Go off and generate some report based on the selected polygon attributes
MyReportGenerator.CreateReport(featuresAttributes);

Best Answer

You can use dictionaries for this type of thing. There are more memory efficient ways of doing this (by just storing field names once), but this might get you started.

public void TestGetSelection()
{
    var dict = GetSelection(ArcMap.Document.FocusMap.get_Layer(0) as IFeatureLayer);
    foreach (KeyValuePair<int, Dictionary<string, object>> kvp in dict)
    {
        Debug.Print("{0} {1}", kvp.Key, kvp.Value["State_Name"]);
    }
}

public static Dictionary<int, Dictionary<string, object>> GetSelection(IFeatureLayer fLayer)
{
    // return a dictionary containing one dictionaries for each selected
    // feature where the contained dictionary is keyed by the field name
    var dict = new Dictionary<int, Dictionary<string, object>>();
    ICursor cur = null;
    try
    {
        ((IFeatureSelection)fLayer).SelectionSet.Search(null, false, out cur);
        IRow row;
        while ((row = cur.NextRow()) != null)
        {
            dict.Add(row.OID, RowToDict(row));
        }
    }
    catch
    {
        throw;
    }
    finally
    {
        if (cur != null)
            System.Runtime.InteropServices.Marshal.FinalReleaseComObject(cur);
    }
    return dict;
}

public static Dictionary<string, object> RowToDict(IRow row)
{
    var dict = new Dictionary<string, object>(StringComparer.InvariantCultureIgnoreCase);
    for (int i = 0; i < row.Fields.FieldCount; i++)
    {
        var fld = row.Fields.get_Field(i);
        if (row.get_Value(i) is DBNull)
        {
            // todo: maybe special treatment of nulls here ...
        }
        if(fld.Type != esriFieldType.esriFieldTypeGeometry)
            dict.Add(fld.Name, row.get_Value(i));
    }
    return dict;
}
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