Issue with the order of as: and default: options on param declarations

[schinery]

Am fairly new to Grape, so apologies if this has come up elsewhere already but doing a quick scan I couldn't see anything covering this issue I was having with using both as and default param options.

If I use the following to set an endDate param with a default value and convert it to end_date then the default value behaviour works as expected.

params do
  optional :endDate, type: Date, default: (Date.current + 50.days).end_of_month, as: :end_date
end

Would result in the default param value being set when no param was sent:

(byebug) params
{"end_date"=>Wed, 30 Sep 2020}

However if I use following for the same request, and specify the as option first, the default value is never set on the params, even when using declared (although not sure this would make a difference anyway).

params do
  optional :endDate, as: :end_date, type: Date, default: (Date.current + 50.days).end_of_month
end

Would result in:

(byebug) params
{}
(byebug) declared(params)
{"end_date"=>nil}

I'm assuming this might be a bug with how the param options are being parsed by Grape but wanted to also make sure I wasn't doing something dumb.

[schinery]

As a side note, if there is a better way to convert all incoming camelcase params to snake case without having to use the as option when declaring a param I'd love to know 👍

[dblock]

This looks like a possible bug indeed, try turning it into a spec?

Regarding camelcase, I would try swapping the parameter builder to a Hashie extension that underscores all keys treats all camel case keys indifferently with underscore keys. I believe Rash does that, but it's built on top of Mash and I wouldn't use that because that's crazy. My recommendation would be to write a Hashie extension that only does that. I'd be interested in seeing the results, including both a contribution to hashie and documentation in Grape/blog post for how to accomplish this.

Btw, you probably want a lambda to evaluate on every request, default: -> { (Date.current + 50.days).end_of_month }.

[schinery]

Hey @dblock, I can certainly try putting a spec together for this when I get some time to, same as the Hashie extension.

Regarding the default: -> { (Date.current + 50.days).end_of_month }, I had mine set as this originally, but this produced "default": { } in the Swagger JSON so I thought I had set it up wrong and removed the lambda. The Swagger JSON looked like:

{
  "in": "query",
  "name": "endDate",
  "description": "End date of query",
  "type": "string",
  "format": "date",
  "default": { },
  "required": false
}

Which then sets in the Swagger UI (using https://petstore.swagger.io) the default value to Default value : OrderedMap {}

If this is another bug I can put this in another ticket if that helps keep things separated?

[dblock]

If this is another bug I can put this in another ticket if that helps keep things separated?

That's a grape-swagger issue, so you should probably open a bug there. That said, it's not supposed to interpret a dynamic default value into some kind of documentation. Not sure what one would expect here.

For your API, I suspect you don't want Date.current to be some value every time your server starts/grape loads, but actually change on every request, hence you need a ->.