Sorting a List of Complex Nested Dictionaries in Python - KeyError When Accessing Inner Values
I need help solving Quick question that's been bugging me - I'm stuck on something that should probably be simple... I'm currently trying to sort a list of nested dictionaries based on a specific key that resides a few levels deep in the structure. The dictionaries contain a mix of information about users, including their registration details and preferences. My goal is to sort them based on their registration date, which is stored as a string in the format 'YYYY-MM-DD'. However, I keep running into a `KeyError` when attempting to access the registration date. Here's a portion of the data I'm working with: ```python users = [ {'id': 1, 'info': {'name': 'Alice', 'registration': {'date': '2022-05-01'} }}, {'id': 2, 'info': {'name': 'Bob', 'registration': {'date': '2021-06-15'} }}, {'id': 3, 'info': {'name': 'Charlie', 'registration': {}}}, {'id': 4, 'info': {'name': 'David', 'registration': {'date': '2023-01-10'} }} ] ``` I tried to sort this list using a lambda function like this: ```python sorted_users = sorted(users, key=lambda x: x['info']['registration']['date']) ``` However, I'm getting the following behavior: ``` KeyError: 'date' ``` This behavior occurs for users who do not have the 'date' field in their registration dictionary, such as Charlie. I want to ensure that the sorting still works for users even if the 'date' key is missing. Ideally, I would like users with no registration date to appear at the end of the sorted list. I've tried using the `get` method to avoid the `KeyError`, but I'm not sure how to implement that properly within the sorting function: ```python sorted_users = sorted(users, key=lambda x: x['info']['registration'].get('date', '9999-12-31')) ``` While this approach prevents the behavior, it seems that it still doesn't sort the list as intended, especially since I'm now comparing strings instead of dates. Is there a better way to approach this question? Any advice would be greatly appreciated! I'm working on a application that needs to handle this. I'd really appreciate any guidance on this. This is part of a larger CLI tool I'm building. Is there a better approach? Any ideas how to fix this?