def fetch_and_create_tags(tag_names):
# copy the tag_names list
new_tag_names = tag_names[:]
# find tag names that already exist (case insensitive match)
# and remove those names from our list
lower_case_tags = [t.lower() for t in new_tag_names]
existing_tags = DBSession.query(Tag).\
filter(
func.lower(Tag.name).in_(lower_case_tags)
).all()
for t in existing_tags:
for n in new_tag_names[:]:
if n.lower() == t.name.lower():
new_tag_names.remove(n)
break
# create the tags that don't yet exist
if new_tag_names:
new_tags = [{'name': n, 'slug': slugify(n)} for n in new_tag_names]
DBSession.connection().execute(tags.insert(), new_tags)
DBSession.flush()
existing_tags += DBSession.query(Tag)\
.filter(
Tag.slug.in_([t['slug'] for t in new_tags])
).all()
return existing_tags
