New functions, fixes for various parameters, and contributing more generally?

[kenny-evitt]

There are some nice new functions in the two open PRs – any chance that those could be merged sometime soonish?

I have also written a few others that, after being cleaned-up a little, would make nice additions too.

I also ran into an issue like #8 but for ExAws.RDS.modify_db_instance/2:

iex(29)> with instance_id     = "some-instance-id",
...(29)>      new_instance_id = "#{instance_id}-new" do
...(29)> 
...(29)>   ExAws.RDS.modify_db_instance(
...(29)>     instance_id,
...(29)>     new_db_instance_identifier: new_instance_id
...(29)>   )
...(29)> 
...(29)> end
%ExAws.Operation.RestQuery{
  action: nil,
  body: "",
  http_method: :patch,
  params: %{
    "Action" => "ModifyDBInstance",
    "DBInstanceIdentifier" => "some-instance-id",
    "NewDbInstanceIdentifier" => "some-instance-id-new",
    "Version" => "2014-10-31"
  },
  parser: &ExAws.Utils.identity/2,
  path: "/",
  service: :rds
}

Per the AWS RDS API docs, the parameter should be named "NewDBInstanceIdentifier".

That seems to be a somewhat common issue with parameter names that include an acronym, e.g. "DB", or "AZ".

I also had some trouble with the "VpcSecurityGroupIds.*" parameter(s) for the AWS RDS API action "RestoreDBInstanceFromDBSnapshot". Those are also used by create_db_instance/7 but normalize_opts doesn't seem to handle them correctly. Some code I wrote for those parameters:

          vpc_security_group_ids
          |> Enum.with_index(
            fn group_id, index ->
              {
                "VpcSecurityGroupIds.VpcSecurityGroupId.#{index + 1}",
                group_id
              }
            end
          )
          |> Enum.into(%{})

That also seems like a possibly somewhat common pattern for the various 'collection' parameters for different functions, and probably in any other AWS API with 'AWS API Query' actions/endpoints.

I'm currently working with this library pretty heavily and this would be a good time – for me – to contribute, if you're open to contributions.