I get an error when I wanted to call an empty list of a value in a dictionary in Python-CodePudding

I have a dictionary like below

[{
  “a”: {
    “uuid”: “4458”,
    “created_at”: “2022-10-19 12:20”,
    “source_platform”: “abc”,
    “platform”: “UK”
  },
  “b”:[],
  “c”: [],
  “d”: [],
  “f”: [],
  “e”: [],
  “g”: [],
  “h”: [],
  “i”: [],
  “j”: {}
}]

and I need to return 'no_info' if the list of a key such as 'b' or 'j' is empty.

but when I use this function

def get_lead_first_platform(data: dict) -> str:
        try:
            if isinstance(data.get('b'), list):
                if data.get('b')[0].get('ad_source'):
                    return data.get('b')[0].get('ad_source')
                else:
                    return 'no_info'
        except Exception as e:
            print(f'{inspect.stack()[0][3]} -- {e}')
            return None

it gives me this error get_lead_first_platform -- 'list' object has no attribute 'get'

CodePudding user response：

You need to do the empty check before accessing the list.

def get_lead_first_platform(data: dict) -> str:
    try:
        if isinstance(data.get('b'), list):
            if len(data.get('b')[0]) > 0:
                return data.get('b')[0].get('ad_source')
            else:
                return 'no_info'
    except Exception as e:
        print(f'{inspect.stack()[0][3]} -- {e}')
        return None

CodePudding user response：

You do not "have a dictionary" as you stated. What you have here is a list with a dictionary within it. Hence if you pass it to your function you are actually calling .get() on a list.

So data.get("b") would be

   [{
  “a”: {
    “uuid”: “4458”,
    “created_at”: “2022-10-19 12:20”,
    “source_platform”: “abc”,
    “platform”: “UK”
  },
  “b”:[],
  “c”: [],
  “d”: [],
  “f”: [],
  “e”: [],
  “g”: [],
  “h”: [],
  “i”: [],
  “j”: {}
}].get("b")

Maybe try executing get_lead_first_platform(data[0]).

Edit:

After fixing the error with .get() you will run into an "index out of range" error with the statement data.get('b')[0] if the list "b" is empty.

CodePudding user response：

yes list has no attribute get you should try with join.