recursion - Python recursively appending list function -

having issues recursive function should relatively simple do, can`t seem right.

i have folder structure folders can contain other folders, images or files. associated each folder there permissions. want have function recursively build list of permissions associated each folder.

i have function has_read_permission(request) returns true if folder has permissions , false if not

i have built function so:

def get_child_perms(self, folder, request, perm_list):         # folder contains other folders         if folder.get_children():             # every sub-folder             subfolder in folder.get_children():                 return perm_list.append(self.get_child_perms(subfolder, request, perm_list))         else:             # if folder doesn't have sub-folders containing folders             return [folder.has_read_permission(request)] 

i keep getting none

given folders so:

folder (allowed) - wont check 1 |_first folder (allowed) | |_first sub folder (restricted) | | |_file | | |_file | | |_image | |__second sub folder (allowed) |_second folder (allowed) 

then running get_child_perms() return [true,false,true,true] or [true, [false, true], true]

edit

disregard edit -> asked other question python recursive function missing results

changed abit,

def get_child_perms(self, folder, request, perm_list):         if folder.get_children():             subfolder in folder.get_children():                 perm_list.append(self.get_child_perms(subfolder, request, perm_list))             return perm_list         else:             return [folder.has_read_permission(request)] 

getting:

[[true], [...], [true], [...], [...], [true], [true], [true], [true], [true], [true], [true], [true], [...], [true], [...]]   admin  -folder 1    - files  -folder 2    - files  -folder 3    - files   -folder 4    - subfolder 1       -subsubfolder 1          - files       - files    - subfolder 2       - subsubfolder 2            - files       - files  -folder 5    - subfolder 3        - files    - subfolder 4        - files    - subfolder 5        -files    - files  -folder 6    - files  -folder 7    - subfoler 6        - files    - files  -folder 8    - files 

as pointed out append inplace operation returns none, can avoid using append @ returning list comp:

def get_child_perms(self, folder, request, perm_list):     # folder contains other folders     children =  folder.get_children()     if children:         # every sub-folder         return [self.get_child_perms(subfolder, request, perm_list)                 subfolder in children]     return [folder.has_read_permission(request)] 

you don't need else either can return once function.