Python递归追加列表函数

Question

有递归函数的问题，应该相对简单做，但似乎不能得到正确的。

我有一个文件夹结构，它的文件夹可以包含其他文件夹、图像或文件。每个文件夹都有权限。我想让我的函数递归地构建一个与每个文件夹关联的权限列表。

def get_child_perms(self, folder, request, perm_list):
        # Folder contains other folders
        if folder.get_children():
            # For every sub-folder
            for 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)]

Folder (allowed) - Wont check this one
|_First Folder (allowed)
| |_First sub Folder (restricted)
| | |_File
| | |_File
| | |_Image
| |__Second Sub Folder (allowed)
|_Second Folder (allowed)

改了号，

def get_child_perms(self, folder, request, perm_list):
        if folder.get_children():
            for 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)]

得到：

[[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

Answer 1

for subfolder in folder.get_children():
    perm_list.append(self.get_child_perms(subfolder, request, perm_list))
return perm_list

.append就位。它不返回任何东西。所以您得到的是none