Feature request: query_string_parameters should never be None

Use case

When there are no query string params, app.current_event.query_string_parameters is None which is unexpected.

Solution/User Experience

Proper solution is to make it to behave like an empty dict or to be an actual empty dict.

• avoids extra None checks
• removes one point of surprise which was totally unnecessary

Alternative solutions

No response

Acknowledgment

• This feature request meets Lambda Powertools Tenets
• Should this be considered in other Lambda Powertools languages? i.e. Java, TypeScript

[sthuber90]

I understand it would be a nicer experience if you could always do app.current_event.query_string_parameters.get("id") and not experience his error:

AttributeError: ‘NoneType’ object has no attribute ‘get’

However, I see the or {} as a good enough solution. Alternatively, you can also use get_query_string_value. Even if no query parameters have been provided this call will not fail and you can set a default value to return if the value would be None.

# returns ""
app.current_event.get_query_string_value(name="id", default_value="")

# returns "dummy_id"
app.current_event.get_query_string_value(name="id", default_value="dummy_id")

[peterschutt]

As @a3kov is thinking about it from a web framework perspective, an analogous solution could be a method on the resolver that always returns a dict, e.g., APIGatewayResolver.query_parameters() -> dict. However, I can’t see a precedent for that kind of thing, and it could be a slippery slope of needing to add methods for accessing other things like path params, headers, etc.

maybe need more customer demand for this, and can update the docs with an or {} when accessing query strings in the meantime

Always harder to remove code than to add it:)