How to process bytes field

[mattygiedt]

How do I obtain the data of a 'bytes' field (shown as msg.delegate) into a Buffer?

new Buffer( msg.delegate ); ==> TypeError: First argument needs to be a number, array or string.

[chrisdew]

I'll have a look at this and get back to you in a day or two...

[mattygiedt]

Hi Chris -- just wondering if you had a chance to look at it. The 'delegate' field is actually another protobuf message, if that helps in your testing.

Didn't mean to close issue, thought that closed the comment box.

Regards, -m

On Wed, Jul 24, 2013 at 10:14 AM, Chris Dew notifications@github.comwrote:

I'll have a look at this and get back to you in a day or two...

— Reply to this email directly or view it on GitHubhttps://github.com/chrisdew/protobuf/issues/29#issuecomment-21491973 .

[chrisdew]

Sorry for the delay, I will look this evening.

On 29 July 2013 12:39, mattygiedt notifications@github.com wrote:

Hi Chris -- just wondering if you had a chance to look at it. The 'delegate' field is actually another protobuf message, if that helps in your testing.

Didn't mean to close issue, thought that closed the comment box.

Regards, -m

On Wed, Jul 24, 2013 at 10:14 AM, Chris Dew notifications@github.comwrote:

I'll have a look at this and get back to you in a day or two...

— Reply to this email directly or view it on GitHub< https://github.com/chrisdew/protobuf/issues/29#issuecomment-21491973> .

— Reply to this email directly or view it on GitHubhttps://github.com/chrisdew/protobuf/issues/29#issuecomment-21714154 .

[chrisdew]

Here's how I do it - I hope I've answered your question.

buftest.proto

package com.chrisdew.buftest;

message BufTest {
  optional float num  = 1;
  optional bytes payload = 2;
}

buftest.js

var fs = require('fs');
var Schema = require('protobuf').Schema;

// "schema" contains all message types defined in buftest.proto|desc.
var schema = new Schema(fs.readFileSync('buftest.desc'));

// The "BufTest" message.
var BufTest = schema['com.chrisdew.buftest.BufTest'];

var ob = { num: 42 };
ob.payload = new Buffer("Hello World");

var proto = BufTest.serialize(ob);
console.log('proto.length:', proto.length);

var outOb = BufTest.parse(proto);
console.log('unserialised:', JSON.stringify(outOb));

var payload = new Buffer(outOb.payload);
console.log(payload);

Makefile: (second line begins with a TAB not spaces)

all:
    protoc --descriptor_set_out=buftest.desc --include_imports buftest.proto

output:

$ node buftest.js 
proto.length: 18
unserialised: {"num":42,"payload":{"0":72,"1":101,"2":108,"3":108,"4":111,"5":32,"6":87,"7":111,"8":114,"9":108,"10":100,"length":11}}
payload: <Buffer 48 65 6c 6c 6f 20 57 6f 72 6c 64>

[chrisdew]

P.S. Turning bytes into a JS object and then back into a buffer looks wasteful. Is there a more efficient way to get the (original) buffer?

[mattygiedt]

Thanks Chris. It was actually obvious user error all along. Thanks for the protobuf node library!