koa-json-filter

Middleware allowing the client to filter the response to only what they need, reducing the amount of traffic over the wire using the ?filter=foo,bar,baz querystring parameter.

JSONSelect would also be great for this but I find it's a little too complicated for the average use-case, so this is just a simple key filter.

Installation

$ npm install koa-json-filter

Options

• name querystring param defaulting to "filter"

Filtering customization

You may also set ctx.filter to an array of names to filter on, for example by using a header field X-Filter: name,email.

Example

Object responses

Script:

var filter = require('koa-filter');
var koa = require('koa');
 
var app = koa();
 
app.use(filter());
 
app.use(function *(){
  this.body = {
    name: 'tobi',
    email: '[e-mail]',
    packages: 5,
    friends: ['abby', 'loki', 'jane']
  }
});
 
app.listen(3000);
console.log('app listening on port 3000');

Response:

$ GET /?filter=name
{
  "name": "tobi"
}

Array responses

Script:

var filter = require('koa-filter');
var koa = require('koa');
 
var app = koa();
 
app.use(filter());
 
app.use(function *(){
  this.body = [
    {
      name: 'tobi',
      email: '[e-mail]',
      packages: 5,
      friends: ['abby', 'loki', 'jane']
    },
    {
      name: 'loki',
      email: '[e-mail]',
      packages: 2,
      friends: ['loki', 'jane']
    },
    {
      name: 'jane',
      email: '[e-mail]',
      packages: 2,
      friends: []
    },
    {
      name: 'ewald',
      email: '[e-mail]',
      packages: 2,
      friends: ['tobi']
    }
  ]
});
 
app.listen(3000);
console.log('app listening on port 3000');

Response:

$ GET /?filter=name,email
[
  {
    "name": "tobi",
    "email": "[e-mail]"
  },
  {
    "name": "loki",
    "email": "[e-mail]"
  },
  {
    "name": "jane",
    "email": "[e-mail]"
  },
  {
    "name": "ewald",
    "email": "[e-mail]"
  }
]

License

MIT