CODE SNIPPETS THAT UTILISE THE OVERWRITEFS PYTHON MODULE FOR UPDATING AND MANAGING VIEW RELATIONSHIPS.
THIS IS NOT A FULL PROGRAM BUT JUST BITS AND PIECES.


    # Determine which feature service (A or B version) is the target for updating

    info("Identifying the target hosted layer for view {}".format(hostsedview))
    agolitem = gis.content.search(query=hostsedview, item_type="Feature Layer")
    x = 0
    viewitem = None
    for searchresult in agolitem:
        if searchresult["title"] == hostsedview:
            viewitem = agolitem[x]
            break
        else:
            x = x + 1
    if viewitem is None:
        msg = '**** Error : Hosted view name {} was not found on ArcGIS Online.  '
        msg = msg + ' view:  ' + hostsedview + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        return False

    try:
        outcome = OverwriteFS.getFeatureServiceTarget(viewitem, verbose=max,
                                                      outcome={"success": None, "items": []},
                                                      ignoreDataItemCheck=False)
        if outcome is None:
            msg = '**** Error determining the target hosted layer for deleting (by chunk method).'
            msg = msg + 'Feature Service view:  ' + hostsedview + ' ..  Moving to next layer in list.'
            error(msg)
            email_flag = send_email(FailureSubject, msg)
            return False

    except:
        msg = '***** Error determining the target hosted layer for deleting (by chunk method).'
        msg = msg + ' Feature Service view:  ' + hostsedview + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        return False

    # Get item details of Target service. In this case "view" means the idle target item
    if "view" in outcome:
        targetitem = outcome["view"]
    else:
        msg = '***** Error determining the target hosted layer for deleting (by chunk method).'
        msg = msg + ' Feature Service view:  ' + hostsedview + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        return False


-----------------------
    # Delete rows in the Target layer (by chunks)
    # Get max number of features
    time.sleep(5)
    layerIndex = 0
    fLyr = targetitem.layers[layerIndex]
    try:
        max_objid = fLyr.query(out_statistics=[ \
            {"statisticType": "MAX", "onStatisticField": "objectid", \
             "outStatisticFieldName": "MAX_OBJ"}], return_geometry=False)
        maxoid = max_objid.features[0].attributes['MAX_OBJ']
        SMaxOID = str(maxoid)
        info("{} max Object ID is {}".format(targetitem.title, SMaxOID))
    except:
        msg = '***** Error determining the maximum object ID of feature service : '
        msg = msg + targetitem.title + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        return False

    # Delete individual features in chunks of 10000
    info("Deleting hosted layer records by chunks for service : {0}".format(targetitem.title))
    time.sleep(5)
    i = 0
    step = 10000
    if maxoid is not None:
        while i <= maxoid :
            i += step
            try:
                #fLyr.delete_features(where=f"OID<= {i}")
                fLyr.delete_features(where=f"objectid<= {i}")
            except:
                msg = '***** Error deleting a chunk of records in Feature Service:  '
                msg = msg + targetitem.title + ' ..  Moving to next layer in list.'
                error(msg)
                email_flag = send_email(FailureSubject, msg)
                return False
        info("Deleted records with chunk method. Max ObjectID processed: {}, Service: {}".format(i,targetitem.title))

        ####     END OF DELETE BY CHUNKS


---------------------------------------
        # Truncating Feature Service Before Append to avoid growing object id values
        info("Truncating feature service..")
        time.sleep(5)
        try:
            fLyr.manager.truncate()
        except:
            msg = '***** Error truncating Feature Service:  ' + targetitem.title
            msg = msg + ' ..  WARNING:  THIS FEATURE SERVICE IS NOW EMPTY !!!!    Moving to next layer in list.'
            error(msg)
            email_flag = send_email(FailureSubject, msg)
            return False

    else:
        info("Feature Layer {} was empty..Proceeding with Append".format(targetitem.title))

---------------------------------------------------

    # Append the data from the source file Gdb onto target hosted layer
    info("Appending features from temp File Geodatabase onto service {}".format(targetitem.title))
    time.sleep(5)
    #     fieldmappings = [{"parcelnum": "parcelnum",
    #                        "dcdb_id": "dcdb_id",
    #                        "parcel_number": "parcel_number",
    #                        "seq_num": "seq_num",
    #                        "unit_num": "unit_num",
    #                        "street_num": "street_num",
    #                        "street_num_formatted_incunit": "street_num_formatted_incunit",
    #                        "street_name": "street_name",
    #                        "street_type": "street_type",
    #                        "suburb": "suburb",
    #                        "state": "state",
    #                        "postcode": "postcode",
    #                        "parcel_address": "parcel_address",
    #                        "address_noext": "address_noext",
    #                        "parcel_address_full": "parcel_address_full",
    #                        "lga": "lga"
    #                        }]
    try:
        #fLyr.append(item_id=datastore_item.id, upsert=False, field_mappings=fieldmappings)
        fLyr.append(item_id=source_itemid, upload_format="filegdb", upsert=False, field_mappings=[])

    except:
        msg = '**** Error appending records from Uploaded File Gdb onto {}'.format(targetitem.title)
        msg = msg + ' ..  WARNING:  THIS FEATURE SERVICE IS NOW EMPTY !!!!    Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        return False

-----------------------------------------------------------------------


    # Touch the target feature service to update it's last modified date
    # (Does not overwrite as we have not listed an updateFile)
    info("Updating date modified on feature service {} ".format(targetitem.title))
    time.sleep(5)
    try:
        outcome = OverwriteFS.overwriteFeatureService(targetitem, updateFile=None, touchItems=True, verbose=None,
                                                      touchTimeSeries=True, outcome=None, ignoreItems=[],
                                                      serviceLastModified=0, noIndexes=False, preserveProps=True,
                                                      noWait=False, noProps=False, converter=None, outPath="",
                                                      dryRun=False, ignoreAge=False)

        if outcome is None:
            msg = '***** Error updating modified date on Feature Service:  ' + targetitem.title
            msg = msg + ' ..  Moving to next layer in list.'
            error(msg)
            email_flag = send_email(FailureSubject, msg)
            deletegdbs(gis)
            return False

    except:
        msg = '***** Error updating modified date on Feature Service:  ' + targetitem.title
        msg = msg + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        deletegdbs(gis)
        return False


--------------------------------------------------------------------------------

    #     Swap the Current and Target layers for the service's view
    # Uses  the swapFeatureViewLayers function that would normally overwrite the target layer, however in this case, we are not
    # specifying a source, so the overwrite is ignored, however it still continues to swap the target and current layers around
    # so the view points to the newly refreshed layer.
    # This also backs up the service's properties (eg. Summary, Tag etc) and restores it back to the service

    info('Swapping Target and Current layers for view {} '.format(hostsedview))
    time.sleep(5)
    dry_run = False
    # Only set dry_run true for test mode where it verifies everything without making an overwrite or swapping
    try:
        outcome = OverwriteFS.swapFeatureViewLayers(viewitem, updateFile=None, touchItems=True, verbose=True, \
        touchTimeSeries=False, outcome=None, noIndexes=True,preserveProps=False, noWait=False,noProps=True, \
        converter=None, outPath="", dryRun=False, noSwap=False, ignoreAge=False)
        if outcome is None:
            msg = '***** Error swapping Target and Current layers for view {}'.format(hostsedview)
            msg = msg + ' after appending new data to Target Feature Service ..  Moving to next layer in list.'
            error(msg)
            email_flag = send_email(FailureSubject, msg)
            deletegdbs(gis)
            return False

        else:
            info('Target and Current Layers successfully swapped for view : {}'.format(hostsedview))
    except:
        msg = '***** Error swapping Target and Current layers for view {} after appending new data to Target Feature Service: '.format(hostsedview)
        msg = msg + ' ..  Moving to next layer in list.'
        error(msg)
        email_flag = send_email(FailureSubject, msg)
        deletegdbs(gis)
        return False

    #  For testing purposes just to check swap was successful :
    #info ('\nListing the new target below....')
    #outcome = OverwriteFS.getFeatureServiceTarget(viewitem, max, { "success": None, "items": []}, False)
    return True

------------------------------------------------------------------------

# Delete Uploaded File Geodatabases. (All FGDBs owned by this user.)
    info("Deleting all uploaded File Geodatabases....")
    import shutil
    global source_tempgdbpath
    global email_flag
    global username
    uname = 'owner:' + username

    try:
        agolgdb = gis.content.search(query=uname, item_type="File Geodatabase")
        if len(agolgdb) > 0:
            # print(agolgdb)
            for item in agolgdb:
                item.delete()
    except:
        msg = '***** Error attempting to locate File GDBs on AGOL.   Moving to next layer in list'
        error(msg)
        email_flag = send_email(FailureSubject, msg)

    # Delete temporary File Geodatabases and zip files
    info("Deleting all temporary FGD and zip files....")
    dir = source_tempgdbpath
    for files in os.listdir(dir):
        path = os.path.join(dir, files)
        print('path= ' +path)
        # removes files and subfolders too
        try:
            shutil.rmtree(path)
            print('rmtree success')
        except:
            try:
                os.remove(path)
                print('remove success')
            except OSError:
                msg = '**** Error attempting to delete temp File GDBs and zip files from  ' + source_tempgdbpath + \
                                                                               '   Moving to next layer in list'
                error(msg)
                email_flag = send_email(FailureSubject, msg)
                return False