simple class with function to upload offline events in an offline event set using facebook python sdk

fb_upload_offline_events.py

from facebook_business.adobjects.offlineconversiondataset import OfflineConversionDataSet
from facebook_business.api import FacebookAdsApi

class FacebookService:
    def __init__(self):
        self.api = FacebookAdsApi.init(app_id='your_app_id', app_secret='your_app_secret',
                                       access_token='your_access_token')
        self.offline_dataset = OfflineConversionDataSet('offline_set_id')
        
    def upload_offline_conversion(self, csv_filename):
        df = pd.read_csv(csv_filename, sep=";", dtype=object)
        # df columns are 'order_id', 'value', 'event_time', 'event_name', 'email', 'phone', 'fn', 'ln', 'currency'
        df['value'] = pd.to_numeric(df['value'])
        # event times have to be sent in UNIX timestamp format
        df['event_time'] = (pd.to_datetime(df['event_time']).astype(int) / 10 ** 9).astype(int).astype(str)
        df['match_keys'] = df.apply(lambda row: json.dumps({k: [row[k]] if k in ['email', 'phone'] else row[k] for k in ['email', 'phone', 'fn', 'ln'] if pd.notnull(row[k])}), axis=1)
        del df['email']  # deleting match_keys single columns since they are now useless
        del df['phone']
        del df['fn']
        del df['ln']
        
        data = df.to_dict(orient="records")
        batch_limit = 2000  # Maximum number of events permitted in a single call
        for i in range(0, len(data), step=batch_limit):
            params = {
                'upload_tag': 'purchases_upload',  # This must be a string, unique for all your uploads, that will let you identify them
                'data': data[i:i+batch_limit],
            }
            self.offline_dataset.create_event(params=params)

Hi Nicolò,
Is there a way to view status of these batches uploaded later in a separate python script?

Unfortunately I haven't tried but if there is, try looking at this file of the official sdk, since FB documentation is often vague.
https://github.com/facebook/facebook-python-business-sdk/blob/a53c8ba0e8f7d0b41b385c60089f6ba00fa5c814/facebook_business/adobjects/offlineconversiondataset.py