Add modularity to your hapi route handlers.

Install via npm

npm install hapi-next

Important !!

Series.promise has been added back since version 0.4.0. Also Series.execute function and its function signature has been changed. See below example for changes.

data as a third argument has been removed since version 0.3.0. Install version 0.2.6 and below if you still want to use it.

.continue has been removed for version 0.2.7 and 0.3.1 onwards. This is because of conflict with hapi's inbuild reply.continue(). Use reply.next() for version 0.2.7 and 0.3.1 onwards.

Deprecation Warning !!

Calling reply.next(err) since 0.4.0 needs either an object or just an error message(string). See example for details

Module that allows to inject next() in your route handler

Consider the following route handler in hapi:

handler : function(request, reply) {
    controller.someFunc();
}

and in the controller:

someFunc : function(request,reply) {

    validator.validate(request) 
             .then(function(err,response){
             
                if(err) {
                  return reply({status : '422', error : err});
                }
                
                return controller.someFuncToGetData();
             })
             .then(function(response) {
                
                if(response.err) {
                  return reply({status : 422, 'error' : response.err });
                }
                
                var data = controller.processTheData(response);
                reply(data);
                
             })
             .catch(function(e) {
                reply({'status' : 422,'error' : e});
             });
}

We have the following problem in the above:

1. Violation of SRP.

2. Code gets complex over time.

3. Changing of any function requires checking the whole handler function invocation again.

4. No default error/response sending mechanism. Each function has to explicitly send error/response.

What we can do about it?

Frameworks like Express.JS have a beautiful feature called next() that allows user to invoke functions in any order and completely independent of each other. While this feature is a part of ExpressJS, this can also be implemented as a separate npm module using hapi-next

hapi-next can be used in the following way

Require hapi-next

var Series = require('hapi-next');

and in the handler

handler : function(request,reply) {
    
    var funcArray = [
      validator.validate,
      controller.someFuncToGetData,
      controller.processSomeData
    ];
    
    var series = new Series(funcArray);
    series.execute(request,reply);
}

your functions:

function validate(request,reply) {
  reply.next();
}

function someFuncToGetData(request,reply) {
  db.persons.queryAsync(request.query,function(err,persons) {
    if(err) {
      return reply.next({message : err, status : 422});
    }
    reply.data = persons;
    reply.next();
  });
}

function processSomeData(request,reply) {
  var processed = [];
  reply.data.forEach(function(dataObj) {
    processed.push(dataObj.name);
  });
  reply.data = processed;
  reply.next();
}

Methods

reply.next(err,config) This tells hapi-next to continue executing the next function in the chain. If error is passed as a non-null value, this will break the execution chain and will send the error response back to client. Also the config object is optional. As of now, it only supports sending status, but I'm willing to support more configuration in the future.

reply.data Object used to pass data between functions in the chain. (see function signature in the above example). This defaults to object {success : true}.

What about reply() ?

You're free to call reply() anywhere in the function chain. This will just stop calling the next function in the chain and send the response directly to the client. hapi-next DOES NOT overrides the reply() method.

Change log

0.4.0 Added back series.promise as a new method of passing values in between. This is useful when we don't necessarily need to use callbacks, instead simply return promise frome each function.

0.3.0 Removed data as a third argument from the functions. Use reply.data instead for passing data between functions.

0.2.1 Removed Series.promise and its related componenets

TODO

1. Add Series.parallel() to make functions execute in parallel that are independent and can immediately send a response.