descriptor 'join' requires a 'unicode' object but received a 'str'

Question

Code adapted from here:

#from 'foo_bar' to 'Foo.Bar'
def lower_case_underscore_to_camel_case(self, string):
  print string
  class_ = string.__class__
  return class_.join('.', map(class_.capitalize, string.split('_')))

Output:

client_area
TypeError: descriptor 'join' requires a 'unicode' object but received a 'str'

Especially disappointing since the source code states:

"""Convert string or unicode from lower-case underscore to camel-case"""

How to fix this?

---

Easy fix:

return str.join('.', map(class_.capitalize, string.split('_')))

Could anyone explain me the overall process?

Answer 1

The code seems to introduce unnecessary complexity, but you can do it like that:

#from 'foo_bar' to 'FooBar'
def lower_case_underscore_to_camel_case(self, string):
  print string
  class_ = string.__class__
  return class_.join(class_('.'), map(class_.capitalize, string.split('_')))

And you could actually shorten the last line to be:

return class_('.').join(map(class_.capitalize, string.split('_')))

Also, judging from the code, you will receive something like "Foo.Bar" (notice a dot) from "foo_bar".