proxy-adapter [![Build Status](https://travis-ci.org/leahciMic/proxy-adapter.svg?branch=master)](https://travis-ci.org/leahciMic/proxy-adapter)
=============

A Node.js proxy that allows modification of requests and responses.

## Installation

```bash
npm install --save proxy-adapter
```

## A quick example:

```js
var app = require('express')(),
    proxyAdapter = require('proxy-adapter');

var adapter = proxyAdapter({
    to: 'http://path.to/remote/api',
    context: 'api'
}).get('/person/:id')
  .replaceUrl(function(url, params) {
    return '/user/' + params.id;
  })
  .replaceIncomingData(function(data) {
    return {
        firstName: data.name[0],
        lastName: data.name[1]
    };
  });

app.use(adapter.use());
```

## API

### Create an instance of proxyAdapter
```js
var proxyAdapter = require('proxy-adapter')({to: 'http://path.to/remote'});
```

#### Options

#### to

The endpoint to proxy requests to.

#### context

The API path to listen on, can be an array.

### proxyAdapter.VERB(url)

Creates an adapter for the http VERB, could be one of (`post`, `get`, `put`, `delete`) and url supplied. Url can contain paramaters exactly like Express.

#### Example

```js
proxyAdapter.get('/foo/:name');
```

### proxyAdapter.replaceUrl(callback)

Gives the ability to replace URLs outgoing to the remote server. Your callback will be supplied (url, params).
You are responsible for returning a new url.

#### Example
```js
proxyAdapter.replaceUrl(function(url, params) {
  return '/bar/' + params.name;
});
```

### proxyAdapter.replaceIncomingHeaders(callback)

Gives the ability to replace headers coming from the remote server. Your callback will be supplied the headers
from the remote server, modify the headers and return the new set of headers to be relayed back to the client.

#### Example

```js
proxyAdapter.replaceIncomingHeaders(function(headers) {
  headers['x-auth-token'] = headers.authToken;
  delete headers.authToken;
  return headers;
});
```

### proxyAdapter.replaceOutgoingHeaders(callback)

Gives the ability to replace headers outgoing to the remote server. Your callback will be supplied the headers
from the incoming request, modify the headers and return the new set of headers that will be sent to the proxy.

#### Example

```js
proxyAdapter.replaceOutgoingHeaders(function(headers) {
  headers['x-auth-token'] = headers.authToken;
  delete headers.authToken;
  return headers;
});
```

### proxyAdapter.replaceOutgoingData(callback)

Replace the outgoing data with the modified data returned via the callback. The callback will be supplied with the
data that is being sent to the proxy, and will be expected to return modified data to send to the proxy.

#### Example

```js
proxyAdapter.replaceOutgoingData(function(data) {
  return {
    firstName: data.firstName,
    lastName: data.lastName
  };
});
```

### proxyAdapter.replaceIncomingData(callback)

Replace the incoming data with the modified data returned via the callback. The callback will be supplied with the
data that comes from the proxy, and will be expected to return modified data to send back to the client.

#### Example

```js
proxyAdapter.replaceIncomingData(function(data, req, res) {
  return {
    firstName: data.name.firstName,
    lastName: data.name.lastName
  };
});
```

## Running tests

To run the tests simply run `npm test` from a clone of this repo.