Tutorial

[tylo]

Hey there,

I'm pretty new to Node.JS and had a difficult time understanding your example of how to use ReJSON.

I had to do hours of googling before I found something that worked for me. I first discovered that yield statements only work inside of generator functions. That was easy enough to find out. Of course afterwards I also read about Promises. However, I had a very difficult time finding out how to get your Promises to resolve.

I ended up finding someone who had this code that lets me pass in a generator function, and it resolves all your promises returned in your yield statements.

I'm unsure if there is a better way, but for now it is what I am doing.

reference: https://developers.google.com/web/fundamentals/getting-started/primers/promises

Wrapper code:

function spawn(generatorFunc) {
  function continuer(verb, arg) {
    var result;
    try {
      result = generator[verb](arg);
    } catch (err) {
      return Promise.reject(err);
    }
    if (result.done) {
      return result.value;
    } else {
      return Promise.resolve(result.value).then(onFulfilled, onRejected);
    }
  }
  var generator = generatorFunc();
  var onFulfilled = continuer.bind(continuer, "next");
  var onRejected = continuer.bind(continuer, "throw");
  return onFulfilled();
}

Example code:

spawn(function* example(){
    try{
        var instance = new Rejson();
        yield instance.connect();
        yield instance.set('foo', '.', {
        bar: {
            hello: 'world'
        }
        });

        value = yield instance.get('foo', '.');
    }
    catch(e){
        console.log(e);

    }
    console.log(value);
});

[evanhuang8]

Thanks for the feedback! I agree that generator is a bit confusing and the language itself is moving away from it as well (with the whole async/await).

Technically, everything just returns a promise, so you can yield it or you can just do the good old promise way:

var instance = new Rejson();
instance.connect().then(function() {
  instance.set('foo', '.', {
    bar: {
      hello: 'world'
    }
  }).then(function() {
    instance.get('foo', '.').then(function(value) {
      console.log(value);
    });
  });
});

[lassebenni]

I totally agree with tylo. Thank you evan for the code above, it helped me as I was unfamiliar with the yield keyword. Maybe add a note on the README?

[Gurpret7]

Unhandled rejection ReplyError: WRONGTYPE Operation against a key holding the wrong kind of value at JavascriptReplyParser.returnError (/home/gurpreet/projects/pcm-edge/node_modules/iorejson/node_modules/ioredis/lib/redis/parser.js:25:25) at JavascriptReplyParser.run (/home/gurpreet/projects/pcm-edge/node_modules/iorejson/node_modules/redis-parser/lib/javascript.js:135:18) at JavascriptReplyParser.execute (/home/gurpreet/projects/pcm-edge/node_modules/iorejson/node_modules/redis-parser/lib/javascript.js:112:10) at Socket. (/home/gurpreet/projects/pcm-edge/node_modules/iorejson/node_modules/ioredis/lib/redis/event_handler.js:107:22) at Socket.emit (events.js:182:13) at addChunk (_stream_readable.js:283:12) at readableAddChunk (_stream_readable.js:264:11) at Socket.Readable.push (_stream_readable.js:219:10) at TCP.onread (net.js:639:20)