Proto3 canonical JSON support

[johncsnyder]

There are a number of open issues related to this. According to #351:

Not yet supported:

"NaN", "Infinity" strings for floats
Any, Timestamp, Duration, Struct, Wrappers, FieldMask, ListValue, Value, NullValue are handled like messages
Feel free to reopen!

Any type url fix:

• handle 'type.googleapis.com/' string #850
• PR fix: google.protobuf.Any type_url fixes #1068 seems to fix that issue

Struct, Value:

• Well-known types support (Struct, Value) #839

Related:

• Reading from the proto3 json standard #916
• proto3 JSON serialization #1108

[johncsnyder]

I have a working implementation that supports Timestamp and Duration well-known types here johncsnyder@a6eddb4

It probably needs a bit of work before making a PR, as it does not support all the cases covered under https://developers.google.com/protocol-buffers/docs/proto3#json and it changes the default toJSON functionality to output Timestamp and Duration as their string representations. Would appreciate some guidance here and how to incorporate this into protobufjs without breaking existing usage.

It creates the following wrappers

// Custom wrapper for Timestamp
wrappers[".google.protobuf.Timestamp"] = {
    fromObject: function(object) {
        if (typeof object === "string") {
            const ts = new Date(object);
            const seconds = Math.floor(ts.getTime() / 1000);
            const nanos = ts.getMilliseconds() * 1000000;
            return this.create({
                seconds: seconds,
                nanos: nanos
            });
        } else if (object instanceof Date) {
            const seconds = Math.floor(object.getTime() / 1000);
            const nanos = object.getMilliseconds() * 1000000;
            return this.create({
                seconds: seconds,
                nanos: nanos
            });
        }

        return this.fromObject(object);
    },

    toObject: function(message, options) {
        if (options && options.json) {
            return new Date(message.seconds * 1000 + message.nanos / 1000000);
        }
        return this.toObject(message, options);
    }
};

// Custom wrapper for Duration
wrappers[".google.protobuf.Duration"] = {
    fromObject: function(object) {
        if (typeof object === "string") {
            const unit = function() {
                if (object.slice(-1) == "s") return 1;
                if (object.slice(-1) == "m") return 60;
                if (object.slice(-1) == "h") return 60 * 60;
                if (object.slice(-1) == "d") return 60 * 60 * 24;
                throw new Error("invalid duration unit : must be one of s, m, h, or d")
            }();
            const value = parseInt(object.slice(0,-1));
            const seconds = value * unit;
            return this.create({
                seconds: seconds,
                nanos: 0,
            });
        }
        return this.fromObject(object);
    },

    toObject: function(message, options) {
        if (options && options.json && message.nanos == 0) {
            return message.seconds.toString() + "s"
        }
        return this.toObject(message, options);
    }
};

It also relaxes the object type check for Timestamp and Duration to support parsing the default message object structure as well as the string representation Eg parsing both {seconds: 1234, nanos: 5678} or 2019-01-01T00:00:00Z are supported for Timestamp.

[ntindall]

Related: #1258