ArcObjects - enumerating feature classes and datasets within a geodatabase - vba

Question

I'm trying to enumerate the contents (feature classes and feature datasets, not interested in tables, etc) of a file geodatabase using vba/arcobjects.
I have the file GDB set as an IGxDatabase object, but can't find a way of getting further in. I've had a look at the geodatabase object model and tried using IFeatureClass and IFeatureDataset but neither seem to return useful results.
Thanks in advance for any assistance

Answer 1

It is much faster to enumerate the names contained in a geodatabase instead of the things that the names can open. The tricky part is looping through names in a featuredataset. While IFeatureWorkspace.Open can be used to open a featureclass without first opening the featuredataset that contains it, getting at featureclassnames within a featuredataset requires opening the featuredataset.
If you know for sure you'll need to open each featureclass, then I suppose it wouldn't hurt to use IWorkspace.Datasets, IEnumDataset, and IDataset instead of IWorkspaceDatasetNames, IEnumDatasetname and IDatasetname.
Option Explicit
Sub TestGetContents()
Dim pGxApp As IGxApplication
Set pGxApp = Application
If Not TypeOf pGxApp.SelectedObject Is IGxDatabase Then
Debug.Print "select a geodb first"
Exit Sub
End If
Dim c As Collection
Set c = GetContents(pGxApp.SelectedObject)
Dim l As Long
For l = 1 To c.Count
Dim pName As IName
Set pName = c.Item(l)
If TypeOf pName Is IFeatureClassName Then
Dim pFC As IFeatureClass
Set pFC = pName.Open
Debug.Print pFC.AliasName, pFC.FeatureCount(Nothing)
ElseIf TypeOf pName Is IFeatureDatasetName Then
Dim pDSName As IDatasetName
Set pDSName = pName
Debug.Print pDSName.name, "(featuredataset)"
End If
Next l
End Sub
Function GetContents(pGxDB As IGxDatabase) As Collection
Dim c As New Collection
Dim pEnumDSName As IEnumDatasetName
Set pEnumDSName = pGxDB.Workspace.DatasetNames(esriDTAny)
Dim pDSName As IDatasetName
Set pDSName = pEnumDSName.Next
Do Until pDSName Is Nothing
If TypeOf pDSName Is IFeatureClassName Then
c.Add pDSName
ElseIf TypeOf pDSName Is IFeatureDatasetName Then
c.Add pDSName
AddSubNames pDSName, c
End If
Set pDSName = pEnumDSName.Next
Loop
Set GetContents = c
End Function
Sub AddSubNames(pDSName1 As IDatasetName, c As Collection)
Dim pEnumDSName As IEnumDatasetName
Set pEnumDSName = pDSName1.SubsetNames
pEnumDSName.Reset
Dim pDSName2 As IDatasetName
Set pDSName2 = pEnumDSName.Next
Do Until pDSName2 Is Nothing
If TypeOf pDSName2 Is IFeatureClassName Then
c.Add pDSName2
End If
Set pDSName2 = pEnumDSName.Next
Loop
End Sub

Answer 2

you can use the ListFeatureClasses Method on the Geoprocessor
(the following shows how this can be done in C#)
IGeoProcessor gp = new GeoProcessorClass();
gp.SetEnvironmentValue("workspace", #"C:\temp");
IGpEnumList gpEnumList = gp.ListFeatureClasses("*", "Polygon", "");
string fc = gpEnumList.Next();
while (fc != "")
{
//Do whatever
}