Working with loguru in order to write a list back to the configuration file, and received the dreaded unsupported operand type(s) for +: 'NoneType' and 'list' error. I know the error came from attempting to combine a literal and a list. I attempted to break down the line by using a variable to represent the literal, and this only generated the same error.
def update_config(config: dict):
"""
Update exisitng configuration file.
Parameters
----------
config: dict
Configuraiton to be written into config file.
"""
config["ids_to_retry"] = list(set(config["ids_to_retry"] + FAILED_IDS))
with open("config.yaml", "w") as yaml_file:
yaml.dump(config, yaml_file, default_flow_style=False)
logger.info("Updated last read message_id to config file")
Traceback (most recent call last):
File "/telegram-downloader-quackified/media_downloader.py", line 359, in <module>
main()
File "/telegram-downloader-quackified/media_downloader.py", line 343, in main
updated_config = asyncio.get_event_loop().run_until_complete(
File "/miniconda3/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
return future.result()
File "/telegram-downloader-quackified/media_downloader.py", line 324, in begin_import
update_config(config)
File "/telegram-downloader-quackified/media_downloader.py", line 35, in update_config
config["ids_to_retry"] = list(set(config["ids_to_retry"] + FAILED_IDS))
I know something needs to change in the phrase list(set(config["ids_to_retry"] + FAILED_IDS)), I just am not sure what.
FAILED_IDS is a list generated when the script encounters an exception and cannot successfully complete the download. When this occurs the message id is stored in memory like so FAILED_IDS.append(message.message_id). Then it is written to the configuration file with the following statement:
if FAILED_IDS:
logger.info(
"Downloading of %d files failed. "
"Failed message ids are added to config file.\n",
len(set(FAILED_IDS)),
)
update_config(updated_config)
It's original value is:
FAILED_IDS: list = []
Where "ids_to_retry" is more or less just a label used in the configuration file. It is just a literal string, and is the nonetype. The ends result is for the two to be written in the configuration file to resemble something like the following:
ids_to_retry:
- 26125
- 2063
- 2065
- 2080
- 2081
- 22052
- 21029
- 553
- 554
- 555
- 2102
- 22074
I hope this clarifies the nature of the variables we are working with.
The reason for failure is config["ids_to_retry"] = None and you are trying to extend a Nonetype to a list. You can use something like
config["ids_to_retry"] = list(set(config["ids_to_retry"] + FAILED_IDS)) if config["ids_to_retry"] else FAILED_IDS
So if config["ids_to_retry"] is None it would take config["ids_to_retry"] = FAILED_IDS, Without trying to extending it.
Assumption made that FAILED_IDS is a list if not you can type cast it to a list.