TypeError：函数缺少1个必需的位置参数：“ path”烧瓶Python

Question

I have a static folder and my main usage is a sub-directory there that is found in root/static/images/monkeys

I have a flask app and I have a variable like so:

app = Flask(__name__)
monkeys_folder_path = os.path.join(app.static_folder, 'images', 'monkeys')

I use it in two functions, one function serves a static image in that folder, this function works:

@app.route('/monkey/<address>')
def serve_static(address):
    # this creates an image in /static/images/monkeys
    monkey_generator.create_monkey_from_address(address)
    filename = address + ".png"
    return send_from_directory(monkeys_folder_path,filename)

I also have another function that uses this path, this function deletes images after X seconds from the folder

def remove_monkey_images(path):
  threading.Timer(5.0, remove_monkey_images).start()
  # this function iterates in a loop over the files in the path and deletes them
  helper_functions.delete_images(path)

This function does not work, when I run the server locally I get

 File "C:\Users\user\AppData\Local\Programs\Python\Python36-32\lib\threading.py", line 1182, in run
    self.function(*self.args, **self.kwargs)
TypeError: remove_monkey_images() missing 1 required positional argument: 'path'

I call the function like so:

remove_monkey_images(path=monkeys_folder_path)

Thanks.

Answer 1

Python function can have positional or keyword parameters . Your function definition

def remove_monkey_images(path)

describe function with one positional parameter. This function could be called only with one positional argument like

remove_monkey_images(monkeys_folder_path)

If you want to use keyword argument you needs

def remove_monkey_images(path='/some_default_path')

In this case you could call function both with

remove_monkey_images(monkeys_folder_path)

and

remove_monkey_images(path=monkeys_folder_path)

and

remove_monkey_images()

In latter case inside function argument path will have default value '/some_default_path'.

Answer 2

When you create the Timer , you have to pass it the called function's arguments, like this:

threading.Timer(5.0, remove_monkey_images, (path,)).start()

Source

As for the rest of your code I don't really know if it's consistent, but at least that's the cause of the error you're getting.

Answer 3

there is a syntax issue with your problem.

Either do this:

remove_monkey_images(monkeys_folder_path)

instead of

remove_monkey_images(path=monkeys_folder_path)

or

Update your function definition as:

def remove_monkey_images(path=None):
  threading.Timer(5.0, remove_monkey_images).start()
  # this function iterates in a loop over the files in the path and deletes them
  helper_functions.delete_images(path)