I have a dict which is formatted as {int:[]}
When I was trying to set value to a key-value pair where the value list is NULL, I got KeyError: 2
tags = {}
tags.setdefault(int,[])
for tag_id in (db.session.query(PostTagRel).filter(PostTagRel.id == post_id).first().tag_id.split(',')):
tag = db.session.query(Tag).filter(Tag.tag_id == tag_id).first().tag_name
tags[post_id].append(tag)
What should I do?
1 Answer
In order to set a general default value for all keys, you can use defaultdict:
from collections import defaultdict
d = defaultdict(list)
d[0].append(1)
