Scheduling tasks with dynamic arguments to run periodically with celery in django - django

Question

I have a tasks that contains dynamic arguments I want to run periodically, how do I pass dynamic elements to the tasks arguments when the task is being called in django celery beat?
Here is the task I want to run periodically:
#task(bind=True)
def generate_export(export_type, xform, export_id=None, options=None):
"""
Create appropriate export object given the export type.
param: export_type
param: xform
params: export_id: ID of export object associated with the request
param: options: additional parameters required for the lookup.
binary_select_multiples: boolean flag
end: end offset
ext: export extension type
dataview_pk: dataview pk
group_delimiter: "/" or "."
query: filter_query for custom queries
remove_group_name: boolean flag
split_select_multiples: boolean flag
index_tag: ('[', ']') or ('_', '_')
show_choice_labels: boolean flag
language: language labels as in the XLSForm/XForm
"""
username = xform.user.username
id_string = xform.id_string
end = options.get("end")
extension = options.get("extension", export_type)
filter_query = options.get("query")
remove_group_name = options.get("remove_group_name", False)
start = options.get("start")
export_type_func_map = {
Export.XLS_EXPORT: 'to_xls_export',
Export.CSV_EXPORT: 'to_flat_csv_export',
Export.DHIS2CSV_EXPORT: 'to_dhis2csv_export',
Export.CSV_ZIP_EXPORT: 'to_zipped_csv',
Export.SAV_ZIP_EXPORT: 'to_zipped_sav',
Export.GOOGLE_SHEETS_EXPORT: 'to_google_sheets',
}
if xform is None:
xform = XForm.objects.get(
user__username__iexact=username, id_string__iexact=id_string)
dataview = None
if options.get("dataview_pk"):
dataview = DataView.objects.get(pk=options.get("dataview_pk"))
records = dataview.query_data(dataview, all_data=True,
filter_query=filter_query)
total_records = dataview.query_data(dataview,
count=True)[0].get('count')
else:
records = query_data(xform, query=filter_query, start=start, end=end)
if filter_query:
total_records = query_data(xform, query=filter_query, start=start,
end=end, count=True)[0].get('count')
else:
total_records = xform.num_of_submissions
if isinstance(records, QuerySet):
records = records.iterator()
export_builder = ExportBuilder()
export_builder.TRUNCATE_GROUP_TITLE = True \
if export_type == Export.SAV_ZIP_EXPORT else remove_group_name
export_builder.GROUP_DELIMITER = options.get(
"group_delimiter", DEFAULT_GROUP_DELIMITER
)
export_builder.SPLIT_SELECT_MULTIPLES = options.get(
"split_select_multiples", True
)
export_builder.BINARY_SELECT_MULTIPLES = options.get(
"binary_select_multiples", False
)
export_builder.INCLUDE_LABELS = options.get('include_labels', False)
export_builder.INCLUDE_LABELS_ONLY = options.get(
'include_labels_only', False
)
export_builder.INCLUDE_HXL = options.get('include_hxl', False)
export_builder.INCLUDE_IMAGES \
= options.get("include_images", settings.EXPORT_WITH_IMAGE_DEFAULT)
export_builder.VALUE_SELECT_MULTIPLES = options.get(
'value_select_multiples', False)
export_builder.REPEAT_INDEX_TAGS = options.get(
"repeat_index_tags", DEFAULT_INDEX_TAGS
)
export_builder.SHOW_CHOICE_LABELS = options.get('show_choice_labels',
False)
export_builder.language = options.get('language')
# 'win_excel_utf8' is only relevant for CSV exports
if 'win_excel_utf8' in options and export_type != Export.CSV_EXPORT:
del options['win_excel_utf8']
export_builder.set_survey(xform.survey, xform)
# change the dhis2csv exports to standard csv format
if extension == 'dhis2csv':
extension = 'csv'
temp_file = NamedTemporaryFile(suffix=("." + extension))
columns_with_hxl = export_builder.INCLUDE_HXL and get_columns_with_hxl(
xform.survey_elements)
# get the export function by export type
func = getattr(export_builder, export_type_func_map[export_type])
try:
func.__call__(
temp_file.name, records, username, id_string, filter_query,
start=start, end=end, dataview=dataview, xform=xform,
options=options, columns_with_hxl=columns_with_hxl,
total_records=total_records
)
except NoRecordsFoundError:
pass
except SPSSIOError as e:
export = get_or_create_export(export_id, xform, export_type, options)
export.error_message = str(e)
export.internal_status = Export.FAILED
export.save()
report_exception("SAV Export Failure", e, sys.exc_info())
return export
# generate filename
basename = "%s_%s" % (
id_string, datetime.now().strftime("%Y_%m_%d_%H_%M_%S_%f"))
if remove_group_name:
# add 'remove group name' flag to filename
basename = "{}-{}".format(basename, GROUPNAME_REMOVED_FLAG)
if dataview:
basename = "{}-{}".format(basename, DATAVIEW_EXPORT)
filename = basename + "." + extension
# check filename is unique
while not Export.is_filename_unique(xform, filename):
filename = increment_index_in_filename(filename)
file_path = os.path.join(
username,
'exports',
id_string,
export_type,
filename)
# seek to the beginning as required by storage classes
temp_file.seek(0)
export_filename = default_storage.save(file_path,
File(temp_file, file_path))
temp_file.close()
dir_name, basename = os.path.split(export_filename)
# get or create export object
export = get_or_create_export(export_id, xform, export_type, options)
export.filedir = dir_name
export.filename = basename
export.internal_status = Export.SUCCESSFUL
# do not persist exports that have a filter
# Get URL of the exported sheet.
if export_type == Export.GOOGLE_SHEETS_EXPORT:
export.export_url = export_builder.url
# if we should create a new export is true, we should not save it
if start is None and end is None:
export.save()
return export
and this is where I call the tasks in the celery beat schedule:
CELERY_BEAT_SCHEDULE = {
'download_csv': {
'task': 'onadata.libs.utils.export_tools.generate_export',
# There are 4 ways we can handle time, read further
'schedule': crontab(minute='*'),
# If you're using any arguments
'args': ()
}
}
how do I pass parameters into the arguments for the tasks??

Answer 1

There is no way to pass argument dynamically in Celery Beat. I think your function is not suitable with periodic task.
Instead of giving a factor directly to the generate_export function, it must be changed to get the required items within the function. Or change to a simple asynchronous operation.

Answer 2

I faced a similar problem. The args field in beat_schedule is fixed at startup and does not change afterward.
But there is a hackish way to pass different arguments to your task.
Use the before_task_publish signal to add custom data in headers.
from celery.signals import before_task_publish
#before_task_publish.connect
def before_publish(sender=None, headers=None, body=None, **kwargs):
if sender == "tasks.generate_export":
headers["custom_args"] = {
"export_type": "some_val"
"xform": "some_val"
"export_id": get_export_id()
"options": options_dict
}
By default, Celery uses JSON serializer. So, make sure the data you add to headers are JSON serializable. Alternatively, you can use pickle to serialize the data, but it brings security concerns with it.
Now you can access these headers in a bound task.
#task(bind=True)
def generate_export(self):
args = self.request.get("custom_args", None)
# do something with args