Flickrapi giving a TypeError: __init__() takes at least 3 arguments (3 given) - class

Question

I am going back and working through old coursework from my intro to comp sci class, and on one of the labs I'm supposed to use the flickrapi module to scrape flickr for a set of pictures to use for the rest of the lab. The project was assigned with some code to scrape flickr that I know should work, but whenever I run the code it throws a TypeError. The function that is returning an error is:
def getphotos(apicode, query, num_images):
''' Return a list of URLs that have a tag that
matches the query code. '''
# Form the object that will interact with the Flickr website
flickr = flickrapi.FlickrAPI(apicode, format='etree')
# Get each matching photo and store in a list, stopping when we
# reach the target number of images
photos = []
for photo in flickr.walk(tags = query, tag_mode = 'all', safe_search = '0', sort = 'interestingness-desc'):
url = "http://farm" + photo.get('farm') + ".staticflickr.com/" + \
photo.get('server') + "/" + photo.get('id') + "_" + \
photo.get('secret') + ".jpg"
print url
photos.append(url)
if len(photos) >= num_images:
break
return photos
The line that throws the error is flickr = flickrapi.FlickrAPI(apicode, format='etree') where apicode represents an apicode key given to me by flickr and I'm not quite sure what the format ='etree' does. When I go look at the flickrapi module and go into core.py, I get to the FlickrAPI class. The part of the class that seems to be of interest is given as:
class FlickrAPI(object):
"""Encapsulates Flickr functionality.
Example usage::
flickr = flickrapi.FlickrAPI(api_key)
photos = flickr.photos_search(user_id='73509078#N00', per_page='10')
sets = flickr.photosets_getList(user_id='73509078#N00')
"""
REST_URL = 'https://api.flickr.com/services/rest/'
UPLOAD_URL = 'https://up.flickr.com/services/upload/'
REPLACE_URL = 'https://up.flickr.com/services/replace/'
def __init__(self, api_key, secret, username=None,
token=None, format='etree', store_token=True,
cache=False):
...(followed by logic statements involving the inputs for __init__ and class methods)
When flickr gives me an apicode key, it also gives me a secret key which I have stored in a .txt file in the same directory as the program I'm working on.
Now obviously the call on the FlickrAPI class is being passed 3 arguments, 2 of which are the apicode key and the format ='etree', but I'm a little bit unsure as to what the third one is. Is the class somehow calling on the secret key through flickr, or is it one of the other inputs for init? How do I got about fixing the type error that the code is giving me?

Answer 1

The three required arguments are self, api_key and secret (arguments that have no default value), the example given in the docstring of the FlickrAPI does not work.
Here, the first argument, self, is implicit (it's the instance of the FlickrAPI being constructed itself), you are giving the second argument, api_key, with apicode, but the third required argument, secret, is missing. format is the third argument you give, but it doesn't count in the three required arguments, as it has a default value.

Answer 2

The problem is that you don't pass anything for secret.
Take a look at this example
class Test():
def __init__(self, one, two, three=3):
print one, two, three
Test(1, three=3)
Test.__init__ takes four arguments, of which one (three) has a default value, so it needs at least self, one and two passed to it. self is passed automatically because it is a class method, so that's the first. Then you pass something for one and something for three. You do pass three arguments, which is the minimum, but you pass nothing for two, which doesn't have any default value. That's where the error comes from. You could call Test(1, 2) which has the same number of arguments because then all arguments without a default value are provided.
In your code, you are passing an argument for api_key and an argument for format, but nothing for secret, which doesn't have a default value.