[MESOS-8656] Improve stout JSON -> protobuf message conversion to handle more valid JSONs

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.6.0
• Target Version/s: 1.6.0
• Sprint: Mesosphere Sprint 76
• Story Points: 2
• Assignee: Qian Zhang
• Reporter: Qian Zhang
• Shepherd: Benjamin Mahler
• Created: 09/Mar/18 08:32
• Updated: 14/Mar/18 03:34
• Resolved: 14/Mar/18 03:34

Description

The followings are valid in JSON which can be successfully parsed by Google's protobuf utility function JsonStringToMessage() but can NOT be parsed our stout, i.e., call JSON::parse() to convert the JSON to a stout JSON object and then call protobuf::parse() to parse the JSON object to a protobuf message.

"int32": "-2147483647"
"int64": "-9223372036854775807"
"bool": "true"

The second step (protobuf::parse()) will fail with an error like this:

Not expecting a JSON string for field 'int32'

This error comes from Try<Nothing> operator()(const JSON::String& string) which currently can only convert JSON::String to protobuf string/bytes/enum, so we need to enhance it to be able to convert JSON::String to bools and integers.

What we can parse currently are:

"int32": -2147483647
"int64": -9223372036854775807
"bool": true

We should make the behavior of our stout JSON -> protobuf conversion consistent with Google's.