service/iam: AssumeRolePolicyDocument is a JSON string and requires unescaping

[pete911]

Version of AWS SDK for Go v2.0.0-preview.5

Version of Go (1.11)

Assume role policy document response from iam.GetRoleRequest is url encoded

Steps to reproduce

out, _ := svc.GetRoleRequest(&iam.GetRoleInput{RoleName: aws.String(roleName)}).Send()
document := aws.StringValue(out.Role.AssumeRolePolicyDocument)
// document is url encoded need to decode it
decodedDocument, _ := url.PathUnescape(document)

Decoding/unescaping should be done before the struct is returned. User should NOT know/care about these things.

[pete911]

I don't mind creating PR, but need some pointers, because service/iam/api.go (where the code needs to be added) says Code generated by private/model/cli/gen-api/main.go. DO NOT EDIT.
But cannot find what is calling that main.go. I had a quick look at Makefile ... Can you point me to some docs about project structure etc.

[jasdel]

Thanks for the feature request @pete911. The SDK does not currently have the metadata available to know that the AssumeRolePolicyDocument member's value is a JSON string. I suggest using strconv.Unqoute instead of url.PathUnescape. I think this will ensure consistent results without any side effects.

[pete911]

@jasdel is this because the library is generated from templates? quicker/easier to keep multiple libraries written in different languages up to date? Because to me this seems like quick fix.

[jasdel]

The AWS SDKs for Go (v1 and v2) are generated from models defined by the API service teams. The SDK will consume these models to generate the SDK's API clients, operation methods, and types. Given the current model information the AssumeRolePolicyDocument field is a string value, and the SDK doesn't have a way to know that the value should be unescaped, and is a document. I'll forward this issue onto the service team.

I think what one way we'd like to solve this issue is for fields like AssumeRolePolicyDocument to be decorated in a way that allow the SDK to know they are a JSON document, or at a minimum that the SDK should unescape the field's value during unmarshal.

Also, I mistakenly suggested strconv.Unquote. url.PathUnescape does look to be best workaround for this issue.

[github-actions]

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