Listing all feature classes in File Geodatabase, including within feature datasets?

This routine for arcgis10 returns all fcs (standalone OR within a feature dataset) inside a gdb. Just set your arcpy.env.workspace then do a for loop

def listFcsInGDB():
    ''' set your arcpy.env.workspace to a gdb before calling '''
    for fds in arcpy.ListDatasets('','feature') + ['']:
        for fc in arcpy.ListFeatureClasses('','',fds):
            yield os.path.join(arcpy.env.workspace, fds, fc)

I ended up using gotchula's answer, but without yield because I generally re-use the FC handles created and yield's are used once then discarded it's easier for me to read and understand what fcs.append() is doing than fcs = yield(...).

def listFcsInGDB(gdb):
    ''' list all Feature Classes in a geodatabase, including inside Feature Datasets '''
    arcpy.env.workspace = gdb
    print 'Processing ', arcpy.env.workspace

    fcs = []
    for fds in arcpy.ListDatasets('','feature') + ['']:
        for fc in arcpy.ListFeatureClasses('','',fds):
            #yield os.path.join(fds, fc)
            fcs.append(os.path.join(fds, fc))
    return fcs

gdb = sys.argv [1]
fcs = listFcsInGDB(gdb)
for fc in fcs:
    print fc            

Results:

d:\> python list-all-fc.py r:\v5\YT_Canvec.gdb
Processing  r:\v5\YT_Canvec.gdb
Buildings_and_structures\BS_2530009_0
Buildings_and_structures\BS_2380009_2
Buildings_and_structures\Tower
Buildings_and_structures\Underground_reservoir
...

This is now in a module I call arcplus*. Place with your other code or PYTHONPATH and then:

import arcplus
fcs = arcplus.listAllFeatureClasses('d:\default.gdb')
for fc in fcs:
    print "magic happens with: ", fc

Arcplus also adds wildcard filtering; to process only feature classes that start with "HD_" within feature datasets containing "Hydro"

fcs = arcplus.listAllFeatureClasses(gdb, fd_filter='*Hydro*', fc_filter='HD_*')

.* now on Github, upgraded for 10.x. For arcgis 9.3 see here.

I realise this question is tagged 9.3, but anyone looking for the same answer at 10.1 onwards is better off using arcpy.da.Walk. It is faster and more accurate than ListDatasets/FeatureClasses/Rasters/etc.

import arcpy
import os

for root, dirs, datasets in arcpy.da.Walk('d:\scratch.gdb'):
    for ds in datasets:
        print os.path.join(root, ds)

The walk function works in the same way as python's walk. It iterates through the directories in the given path and at each iteration, root represents the full path of the directory, and dirs and datasets are lists of the subdirectories and files contained within.

When walking through a geodatabase, feature datasets are treated in the same way as directories. If you only want to list the datasets and feature datasets in the root folder and not open up the feature datasets to see the contents, you can do:

for root, dirs, datasets in arcpy.da.Walk('d:\scratch.gdb'):
    print 'feature datasets:'
    for fds in dirs:
        print os.path.join(root, fds)
    print 'datasets:'
    for ds in datasets:
        print os.path.join(root, ds)
    break