Is there a better way to ask if an argument exists AND does it match what I expect?

Question

I’m new to python and I am sure there’s a better way to do this. For my specific issue I have stored an API key. I’ve given the user means to send an argument with a new API key if needed. Otherwise the argument is set as False. So if the user sends an API key, I first want to find out if it’s different from the one I already have. And if it is different I then want to update it in my secret manager.

There’s one addtl layer of possible complication. It’s a header in a webhook.

So I’m writing an if function but it feels very inelegant. This is what I currently have written. I’m also using Flask, hence request.

This is my code:

if request.headers['x-api-key'] and request.headers['x-api-key'] not in stored_api_key:
    # do something

Would love to know how I should be writing this. Thank you.

Asked By: coreyzev

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Source

Answer 1

Flask’s request.headers acts like a dictionary, and so if you do

request.headers['x-api-key']

And the key x-api-key does not exist in the user’s request, this will throw an error. Similar to dict, you can use the .get() method to default to a value in the case it does not exist. In this case, your code would look like so:

api_key = request.headers.get('x-api-key')
if api_key and api_key not in stored_api_key:
    # do something

Otherwise, you must do the following:

if 'x-api-key' in request.headers and request.headers['x-api-key'] not in stored_api_key:

Answered By: Felipe

Answer 2

I wouldn’t try to jam this into a single if statement. You have two checks where one check can use the output of the last. IMO it reads much more clearly to me to have two if statements. You could use an assignment expression to help simplify your logic:

if api_key := request.headers.get('x-api-key'):
    if api_key not in stored_api_key:
        ...

The first if assigns api_key and checks for truthiness. get is used to avoid KeyErrors. The second if uses the value from above where we know api_key is not None.

You could also one liner this if you really want to, but is definitely less readable:

if (key := request.headers.get('x-api-key')) and key not in stored_api_key:
   ...

Answered By: flakes

Is there a better way to ask if an argument exists AND does it match what I expect?

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