Round trip s3api get/put-bucket-lifecycle

[jamesls]

An s3api get-bucket-lifecycle response with an xml node prefix of <prefix></prefix> is parsed as None, which shows up in JSON as null:

$ aws s3api get-bucket-lifecycle --bucket bucket
{
    "Rules": [
        {
            "Status": "Enabled",
            "Prefix": null,  # <--- parsed as null

However, if you try to round trip this response with an s3api put-bucket-lifecycle you'll get a validation error as prefix is expected to be a string:

Invalid type for parameter LifecycleConfiguration.Rules[0].Prefix, value: None, type: <type 'NoneType'>, valid types: <type 'basestring'>

Ideally we should parse an xml node that comes across the wire as <foo></foo> as an empty string if the associated output shape is modeled as a string.

We'll need to evaluate that this is not a breaking change, but the consequence of this change is that there may be fields that previously parsed as null will now show up as an empty string.

Filing this issue for now to track progress.

[jamesls]

Just to follow up here, after discussing this I went ahead and merged the changes. The expected behavior of an empty xml node that's modeled as a string type should default to an empty string instead of null, so this is a bug fix. This also allows for round tripping requests which is a nice side benefit.