I need to run through db using recursion and get a list of results at the end. Function works correct (if print unrem) but I cann't return the list of results.
def find_locks(item, ids):
if item.video_id:
#print (item.video_id, ids)
return (item.video_id, ids)
for i in CatalogItem.objects.filter(parent=item):
if i.is_lock:
find_locks(i, ids.append(i.id))
else:
find_locks(i, ids)
How can I get the list results?
I'd use a recursive generator instead of building a list:
def find_locks(item, ids):
if item.video_id:
yield (item.video_id, ids)
for i in CatalogItem.objects.filter(parent=item):
nxt = ids + [i.id] if i.is_lock else ids
for x in find_locks(i, nxt):
yield x
In python 3.3 you can use yield from for the last part.
Try something like the following:
def find_locks(item, ids):
if item.video_id:
return [(item.video_id, ids)]
res = []
for i in CatalogItem.objects.filter(parent=item):
if i.is_lock:
res.extend(find_locks(i, ids + [i.id]))
else:
res.extend(find_locks(i, ids))
return res
In the base case you return list with the only one item included. If it's not the base case, you make a new list, execute recursive call, extend the list with result of recursive call and return this list.
ids.append(i.id) will return None, which is probably not what he had in mind.You can simply store each result in a list and return that at the end:
def find_locks(item, ids):
if item.video_id:
return [(item.video_id, ids)]
result = []
for i in CatalogItem.objects.filter(parent=item):
if i.is_lock:
result.extend(find_locks(i, ids + [i.id]))
else:
result.extend(find_locks(i, ids))
return result
Note that you need to return each item in a list as well because other calls to find_locks expect to receive a list as return value.
ids.append(i.id) will return None, which is probably not what he had in mind.