TypeError("'bool' object is not iterable",) when trying to return a Boolean

Question

I am having a strange problem. I have a method that returns a boolean. In turn I need the result of that function returned again since I cant directly call the method from the front-end. Here's my code:

# this uses bottle py framework and should return a value to the html front-end
@get('/create/additive/<name>')
def createAdditive(name):
    return pump.createAdditive(name)



 def createAdditive(self, name):
        additiveInsertQuery = """ INSERT INTO additives
                                  SET         name = '""" + name + """'"""
        try:
            self.cursor.execute(additiveInsertQuery)
            self.db.commit()
            return True
        except:
            self.db.rollback()
            return False

This throws an exception: TypeError("'bool' object is not iterable",)

I don't get this error at all since I am not attempting to "iterate" the bool value, only to return it.

If I return a string instead of boolean or int it works as expected. What could be an issue here?

Traceback:

Traceback (most recent call last):
  File "C:\Python33\lib\site-packages\bottle.py", line 821, in _cast
    out = iter(out)
TypeError: 'bool' object is not iterable

Answer 1

Look at the traceback:

Traceback (most recent call last):
  File "C:\Python33\lib\site-packages\bottle.py", line 821, in _cast
    out = iter(out)
TypeError: 'bool' object is not iterable

Your code isn't iterating the value, but the code receiving it is.

The solution is: return an iterable. I suggest that you either convert the bool to a string (str(False)) or enclose it in a tuple ((False,)).

Always read the traceback: it's correct, and it's helpful.