!clean command returns malformed API request

[jb3]

Since we added attachments to the deleted message logs the clean command was not updated to store this.

When running a clean command the following error is returned:

web_1       | Bad Request: /bot/deleted-messages
web_1       | "POST /bot/deleted-messages HTTP/1.1" 400 792
bot_1       | 2020-02-25 19:32:41,081 | bot.cogs.error_handler | DEBUG | API responded with 400 for command clean all: {'deletedmessage_set': [{'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}, {'attachments': ['This field may not be null.']}]}.

This is not critical since the clean command still operates, it just does not store deleted messages like intended.

[SebastiaanZ]

The issue is caused by a small oversight in how ModLog.upload_log handles empty attachment lists. Normally, attachments is a list of lists, with each sublist containing the attachments for that particular message

However, if the attachments kwarg isn't used (i.e., gets the default None value), we initialize attachments with an empty outer list. That results in us adding None from the default value of zip_longests in the request part instead of an empty list indicating that a message had no attachments:

        # here it attaches an empty list
        if attachments is None:
            # Empty list
            attachments = []

        response = await self.bot.api_client.post(
            'bot/deleted-messages',
            json={
                'actor': actor_id,
                'creation': datetime.utcnow().isoformat(),
                'deletedmessage_set': [
                    {
                        'id': message.id,
                        'author': message.author.id,
                        'channel_id': message.channel.id,
                        'content': message.content,
                        'embeds': [embed.to_dict() for embed in message.embeds],
                        'attachments': attachment,
                    }
                    # attachment here will get `None` from `zip_longest` if attachments is an empty list
                    for message, attachment in zip_longest(messages, attachments)
                ]
            }
        )

        return f"{URLs.site_logs_view}/{response['id']}"