Why does except not allow me to enter correct value after catching error?-CodePudding

I have a variable 'action' which I want to input from the user and validate, I have a while loop and a try-except block to catch the values which raise an error or are invalid according to the functionality of the rest of the code

while True: # Input and validation of 'action'
        try:
            action = int(input('Please enter what you would like to do: '))
            if action < 0:
                negativeError = ValueError('This value is negative')
                raise negativeError
            if action != 1 or action != 6:
                invalidValueError = ValueError('Not a valid option')
                raise invalidValueError
            break
        except:
            ValueError or TypeError
            print('That is invalid, please enter a valid number corresponding to one of the actions above')
            continue

If I input for example 1 on the first iteration, it breaks out of the loop as expected, but if I input -5 (which except catches) on the first iteration THEN input 1 in the second iteration it catches it as if 1 is an invalid value and does not break out of the loop and keeps iterating. I am new to error handling so any help would be appreciated.

CodePudding user response：

I think it should look like this:

while True: # Input and validation of 'action'
        try:
            action = int(input('Please enter what you would like to do: '))
            if action < 0:
                negativeError = ValueError('This value is negative')
                raise negativeError
            if action not in [1, 6]:
                invalidValueError = ValueError('Not a valid option')
                raise invalidValueError
            break
        except ValueError or TypeError:
            print('That is invalid, please enter a valid number corresponding to one of the actions above')
            continue

action != 1 or action != 6 is always true.

CodePudding user response：

Your if statement is not correct.
Print the message generated during the except raising instead of creating a new message.

while True: # Input and validation of 'action'
    try:
        action = int(input('Please enter what you would like to do: '))
        if action < 0:
            negativeError = ValueError('This value is negative')
            raise negativeError
        if not (action == 1 or action == 6):
            invalidValueError = ValueError('Not a valid option')
            raise invalidValueError
        break
    except (ValueError,TypeError ) as e:
        print(e)

CodePudding user response：

Try something like this. We'll use a default parameter value for now. This can be modified later (i.e., passed by the caller) thus obviating the need to modify this code:

def get_action(valid_actions=[1,6]):
    action_list = ','.join(map(str, valid_actions))
    while True:
        try:
            input_ = input(f'Please select an action from this list {action_list}: ')
            response = int(input_)
            if response in valid_actions:
                return response
            raise ValueError
        except ValueError:
            print('Invalid response. Try again')

get_action()

Subsequently you might want to add another action - say 3. In which case:

get_action([1,3,6])

...is all that you'd need