object-stream-map

object-stream-map

Perform a map on a stream of objects.

Let's say you are consuming an array of objects in the form of a stream. This node module lets you return a named property for each object in the stream, in reality performing a map on the entire array.

In other words it can convert this:

[{ foo: 1 }, { foo: 2 }, { foo: 3 }]

To this:

[1, 2, 3]

Installation

npm install object-stream-map

Example usage

var map = require('object-stream-map');

objectStream        // `objectStream` is a Readable stream pushing an array of objects
  .pipe(map('foo')) // `map('foo')` will forward the `foo` property for each object
  .pipe(process.stdout);

Real world example

Let's say you have a MongoDB database with a collection of users:

{ _id: 1, name: 'Tobias', age: 42 }
{ _id: 2, name: 'Thomas', age: 32 }
{ _id: 3, name: 'Mathias', age: 30 }
{ _id: 4, name: 'Ed', age: 24 }

Now let's say you want to pipe all their names to STDOUT. With object-stream-map you could quickly write it like this:

var map = require('object-stream-map');
var db = require('mongojs')('my-database', ['users']);

db.users.find({}).pipe(map('name')).pipe(process.stdout);

The above code will pipe the following to STDOUT:

Tobias
Thomas
Mathias
Ed

License

MIT