Python Addin and Undo/Redo

Question

There seems to be no way for a Python addin to access the startOperation and stopOperation functions provided by the Editor class. A stand-alone script can use them, but I'd like to be able to click a button provided by an addin and update some data in the map and have the edit appear in the undo/redo stack as was possible in VBA.

Am I missing something? I can do the editing part, but the edits do not appear in the undo/redo stack automatically, and I can't get the Editor class to work.

The API does not include a label for the stopOperation() method as VBA had, so it looks as if the Editor class was not designed to work with Python addins.

ThomasLaxson · Answer

No need to mess around with ArcObjects and .NET. You can create your own edit stack. You can simply set a global variable that tracks the edits and is then accessible to other buttons. For example, depending on the complexity of the edits performed by your add-in, you could have a global list to which you append information about the edits. Here's an example of a simple edit button (it just buffers the selected features) with undo and redo buttons. Note that these are not the built-in undo/redo buttons, but Add-In buttons that you create. The edits here will be in a separate stack from the built-in edits. import arcpy import pythonaddins MXD = arcpy.mapping.MapDocument('CURRENT') FN_SHAPE = 'SHAPE@' # Global variables that will store the edit histories forward and backward undo_stack = list() redo_stack = list() class MakeEdits(object): def __init__(self): self.enabled = True self.checked = False def onClick(self): # Get the selected layer in the table of contents lyr = pythonaddins.GetSelectedTOCLayerOrDataFrame() # Get a count of selected features in the selected layer fid_set = arcpy.Describe(lyr).FIDSet if fid_set == '': count = 0 else: count = len(fid_set.split(';')) # If at least one feature is selected if count > 0: # Enable global modification of the undo_stack global undo_stack # Get the name of the layer's OID field fn_oid = arcpy.Describe(lyr).OIDFieldName with arcpy.da.UpdateCursor(lyr, [fn_oid, FN_SHAPE]) as cur: for row in cur: # Add the relevant details to the editing stack undo_stack.append((lyr, fn_oid, row[0], row[1])) # An arbitrary example edit row[1] = row[1].buffer(500) cur.updateRow(row) arcpy.RefreshActiveView() class RedoEdits(object): def __init__(self): self.enabled = True self.checked = False def onClick(self): global undo_stack global redo_stack if len(redo_stack) > 0: # Get the last item in the edit stack edit = redo_stack.pop() # Clear any existing selection on the layer, or else the cursor may # not hit the necessary feature arcpy.SelectLayerByAttribute_management(edit[0], 'CLEAR_SELECTION') # A where clause to select the most recently edited feature wc = '{} = {}'.format(edit[1], edit[2]) with arcpy.da.UpdateCursor(edit[0], FN_SHAPE, wc) as cur: for row in cur: # Update the undo edit stack edit_out = list(edit[:-1]) edit_out.append(row[0]) undo_stack.append(edit_out) # Apply the edit row[0] = edit[3] cur.updateRow(row) break arcpy.RefreshActiveView() class UndoEdits(object): def __init__(self): self.enabled = True self.checked = False def onClick(self): global undo_stack global redo_stack if len(undo_stack) > 0: edit = undo_stack.pop() arcpy.SelectLayerByAttribute_management(edit[0], 'CLEAR_SELECTION') wc = '{} = {}'.format(edit[1], edit[2]) with arcpy.da.UpdateCursor(edit[0], FN_SHAPE, wc) as cur: for row in cur: edit_out = list(edit[:-1]) edit_out.append(row[0]) redo_stack.append(edit_out) row[0] = edit[3] cur.updateRow(row) break arcpy.RefreshActiveView() return‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

JohnDye · Answer

Mark & Nobbir,

Actually, you can access the .NET Editor and functions through Python Addins. It's a bit of a workaround though. What you need to do is directly reference the .NET ProgID for the builtin function you are looking for in the Config.xml. In your case, you need to alter your Python Addin button refID to directly reference the .NET ProgID for the Start/Stop/Save Edit Commands. Since you would then be directly accessing the .NET Editor functions, that should perform the edits in the fashion you desire.

Jason Pardy did a really good blog post on this in August. Give it a read, I think it will solve your problem.

Hope it helps,
John

gpnobbir · Answer

I think what Mark is looking for is an equivalent of Editor extension of .Net. If so, that is not possible with Python add-in.

However, you can listen to various editing events from a Python add-in.

Check out the help topic on Application Extension - you'll find the following editing events can be listened to:

onEditorSelectionChanged
onCurrentLayerChanged
onCurrentTAskChanged
onStartEditing
onStopEditing
onStopOperation
beforeStopOperation
onStopOperation
onSaveEdits

... and few more.