Call exported function koajs

Question

I have a koa app which has a bunch of functions split up into separate files. When one route is called I need to pass the context this to another function (which is also a route) in an separate file.

File a.js route - http://127.0.0.1:3000/foo

exports.foo = function *() {
  this.body = 'Some Value';
}

File b.jsroute - http://127.0.0.1:3000/bar

var a = require('a');

exports.bar = function *() {
  this.body = yield a.foo(); // this obviously doesn't work.
}

I want to be able to yield a.foo() with the current context (this) and have it operate like it is being called by the normal router.

I think your shared functionality is better placed in a middleware where both `/foo` and `/bar` routes can call `yield this.sharedFeature(opts)`. If you want to go your way, then just do `yield a.foo.bind(this)` — kilianc, Jun 22 '14 at 13:25
Hmmmm, @kilianc seems like doing `yield a.foo.bind(this)` doesn't actually call the function nor return from the function? Is there something special you need to do in `a.foo` ? — sbarow, Jun 22 '14 at 13:31
a.foo is a generator right? then you don't have to do anything in particular, try `a.foo.call(this)` but `.bind` should work too — kilianc, Jun 22 '14 at 15:45
@kilianc you were right, that actually works. If you put that as an answer I will accept. Thanks for your help. — sbarow, Jun 22 '14 at 16:04

kilianc · Accepted Answer · 2014-07-08T13:09:04.260

2

I think your shared functionality is better placed in a middleware where both /foo and /bar routes can call yield this.sharedFeature(opts).

If you want to go your way, then just do yield a.foo.call(this)

edited Jul 08 '14 at 13:09

answered Jun 22 '14 at 16:10

kilianc

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`yield a.foo.call(this)` is better. no need to bind – Jonathan Ong Jun 23 '14 at 22:24

Ben · Answer 2 · 2014-06-20T16:42:28.490

There are few problems there. one is you have to return the value (or pass the value back in the callback). Also there is a problem how a.js is required. You need to add the path to it "./a" (or where ever you store it), not "a". Here is the revision (Note that I'm not including koajs in the code since this is just javascript/nodejs issue):

// a.js
exports.foo = function() {
  this.body = 'Some Value';
  return this;
}

// b.js
var a = require('./a');  // assumes a.js is in same directory as b.js

exports.bar = function () {
  var aThis =a.foo(); 
  console.log(aThis.body);
};

// c.js
var b = require('./b');

b.bar();   // <<<<< prints "Some Value"

This is how the context of bar() can be passed to foo():

// a.js
exports.foo = function(bScope) {
  console.log("this is bValue of b scope: %s", bScope.bValue);
}

// b.js
var a = require('./a');

exports.bar = function () {
  this.bValue = "value of b";
  a.foo(this);
}

// c.js
var b = require('./b');

b.bar();   // <<<<<<<< prints "this is bValue of b scope: value of b"

Not really what I am looking for, specifically I need the context from bar to be passed to foo. Regarding how `a` is required, its just an example. — sbarow, Jun 20 '14 at 16:22

Call exported function koajs

2 Answers2