use []byte or custom type for pubsub Message data

[codyoss]

Expected Behavior

// Option 1
type Message struct {
	Data        []byte        `json:"data,omitempty"`        // The binary data in the message.
}

// Option 2
type Message struct {
	Data        ByteData        `json:"data,omitempty"`        // The binary data in the message.
}

Actual Behavior

type Message struct {
	Data        *string        `json:"data,omitempty"`        // The binary data in the message.
}

Details

The choice to use a string was also made in our HTTP/REST libraries. We did not respect the ”format”: “byte”. We have an open issue around how it would have been nice to generate these types as []byte.

Option 2 might be nice do you could provide a custom mashaller for the type that auto encodes/decodes base64 values so the user of this library does not have to.

[grant]

Ideally we modify quicktype to support generating []bytes with a native JSON schema base64 type.

glideapps/quicktype#1317

---

An alternative would be to look for all the "binaryEncoding": "base64" fields in our schemas and convert the respective golang field types.

[grant]

The implementation of this will be rather complicated. I'll have to check with @grayside on how we can make this possible.

This is one of the cases where using proto/protoc would be nice instead of jsonschema. Proto generation produces a []byte appropriately. There are some upstream jsonschema & jsonschema tooling fixes we'd need to do to natively generate the same base64 []byte from jsonschema.

google-cloudevents-go/src/google/events/cloud/pubsub/v1/data.pb.go

Line 109 in 990cec1

Data []byte `protobuf:"bytes,1,opt,name=data,proto3" json:"data,omitempty"`

[grant]

Here are the instances of protos with bytes:

• Cloud Build: repeated bytes build_step_outputs
• Cloud Build: bytes value
• Cloud Firestore: bytes bytes_value
• Cloud Pub/Sub: bytes data
• Cloud Scheduler: bytes custom_data

[grant]

Should be fixed with the above PR! :)