npm package: @qccareerschool/axios-observable
Description: make axios return Observable as opposed to Promise
Author: Siyang Kern Zhao
Latest version: 1.3.0

# axios-observable
##### Observable (as opposed to Promise) based HTTP client for the browser and node.js
Want to use axios in a rxjs (observable) way? There we go!

This API of axios-observable is almost same as API of axios, giving you smooth transition. So the documentation mirrors the one of axios (A few exceptions will be cleared pointed out).

## Features

- Make [XMLHttpRequests](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest) from the browser
- Make [http](http://nodejs.org/api/http.html) requests from node.js
- Supports the **Observable** API
- Intercept request and response
- Transform request and response data
- (NEW in v1.1.0) Cancel requests through unsubscribe
- Automatic transforms for JSON data
- Client side support for protecting against [XSRF](http://en.wikipedia.org/wiki/Cross-site_request_forgery)

## Installing

Using npm:
note: `axios` and `rxjs` are peer dependencies.

```bash
$ npm install axios rxjs axios-observable
```

## Example

Performing a `GET` request

```js
import Axios from  'axios-observable';
// or const Axios = require('axios-observable').Axios;

// Make a request for a user with a given ID
Axios.get('/user?ID=12345')
  .subscribe(
    response => console.log(response),
    error => console.log(error)
  );

// Optionally the request above could also be done as
Axios.get('/user?ID=12345'), {
    params: {
      ID: 12345
    }
  })
  .subscribe(
    response => console.log(response),
    error => console.log(error)
  );
```

Performing a `POST` request

```js
Axios.post('/user', {
    firstName: 'Fred',
    lastName: 'Flintstone'
  })
   .subscribe(
    response => console.log(response),
    error => console.log(error)
  );
```

## Why observable is better than Promise?
You can do much more! rxjs provides tons of operators to let you gracefully control your request.
##### Example, retry 3 times after failures.
```js
Axios.post('/user', {
    firstName: 'Fred',
    lastName: 'Flintstone'
  })
  .pipe(
  	retry(3)
  )
   .subscribe(
    response => console.log(response),
    error => console.log(error)
  );
```

## axios-observable API

### Yeah! We use the exact same config object as axios.

##### Axios.request(config) (We don't support using Axios as a function as opposed to axios library)
The example below is wrong!
```js
// Send a POST request
Axios({
  method: 'post',
  url: '/user/12345',
  data: {
    firstName: 'Fred',
    lastName: 'Flintstone'
  }
});
```
use Axios.request(config) instead
```js
// Send a POST request
Axios.request({
  method: 'post',
  url: '/user/12345',
  data: {
    firstName: 'Fred',
    lastName: 'Flintstone'
  }
});
```

```js
// GET request for remote image
Axios.request({
  method:'get',
  url:'http://bit.ly/2mTM3nY',
  responseType:'stream'
})
  .subscribe(response => {
  response.data.pipe(fs.createWriteStream('ada_lovelace.jpg'))
});
```

### Request method aliases

For convenience aliases have been provided for all supported request methods.

##### Axios.request(config)
##### Axios.get(url[, config])
##### Axios.delete(url[, config])
##### Axios.head(url[, config])
##### Axios.post(url[, data[, config]])
##### Axios.put(url[, data[, config]])
##### Axios.patch(url[, data[, config]])

###### NOTE
When using the alias methods `url`, `method`, and `data` properties don't need to be specified in config.

### Concurrency

as opposed to axios using `all` and `spread`, rxjs has a much better way of handling concurrency.

### Creating an instance

You can create a new instance of Axios with a custom config.

##### Axios.create([config])

```js
const instance = Axios.create({
  baseURL: 'https://some-domain.com/api/',
  timeout: 1000,
  headers: {'X-Custom-Header': 'foobar'}
});
```

### Instance methods

The available instance methods are listed below. The specified config will be merged with the instance config.

##### Axios#request(config)
##### Axios#get(url[, config])
##### Axios#delete(url[, config])
##### Axios#head(url[, config])
##### Axios#post(url[, data[, config]])
##### Axios#put(url[, data[, config]])
##### Axios#patch(url[, data[, config]])

## Request Config (same as axios, typed with `AxiosRequestConfig` if using TypeScript)

These are the available config options for making requests. Only the `url` is required. Requests will default to `GET` if `method` is not specified.

```js
{
  // `url` is the server URL that will be used for the request
  url: '/user',

  // `method` is the request method to be used when making the request
  method: 'get', // default

  // `baseURL` will be prepended to `url` unless `url` is absolute.
  // It can be convenient to set `baseURL` for an instance of axios to pass relative URLs
  // to methods of that instance.
  baseURL: 'https://some-domain.com/api/',

  // `transformRequest` allows changes to the request data before it is sent to the server
  // This is only applicable for request methods 'PUT', 'POST', and 'PATCH'
  // The last function in the array must return a string or an instance of Buffer, ArrayBuffer,
  // FormData or Stream
  // You may modify the headers object.
  transformRequest: [function (data, headers) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `transformResponse` allows changes to the response data to be made before
  // it is passed to then/catch
  transformResponse: [function (data) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `headers` are custom headers to be sent
  headers: {'X-Requested-With': 'XMLHttpRequest'},

  // `params` are the URL parameters to be sent with the request
  // Must be a plain object or a URLSearchParams object
  params: {
    ID: 12345
  },

  // `paramsSerializer` is an optional function in charge of serializing `params`
  // (e.g. https://www.npmjs.com/package/qs, http://api.jquery.com/jquery.param/)
  paramsSerializer: function(params) {
    return Qs.stringify(params, {arrayFormat: 'brackets'})
  },

  // `data` is the data to be sent as the request body
  // Only applicable for request methods 'PUT', 'POST', and 'PATCH'
  // When no `transformRequest` is set, must be of one of the following types:
  // - string, plain object, ArrayBuffer, ArrayBufferView, URLSearchParams
  // - Browser only: FormData, File, Blob
  // - Node only: Stream, Buffer
  data: {
    firstName: 'Fred'
  },

  // `timeout` specifies the number of milliseconds before the request times out.
  // If the request takes longer than `timeout`, the request will be aborted.
  timeout: 1000,

  // `withCredentials` indicates whether or not cross-site Access-Control requests
  // should be made using credentials
  withCredentials: false, // default

  // `adapter` allows custom handling of requests which makes testing easier.
  // Return a promise and supply a valid response (see lib/adapters/README.md).
  adapter: function (config) {
    /* ... */
  },

  // `auth` indicates that HTTP Basic auth should be used, and supplies credentials.
  // This will set an `Authorization` header, overwriting any existing
  // `Authorization` custom headers you have set using `headers`.
  auth: {
    username: 'janedoe',
    password: 's00pers3cret'
  },

  // `responseType` indicates the type of data that the server will respond with
  // options are 'arraybuffer', 'blob', 'document', 'json', 'text', 'stream'
  responseType: 'json', // default

  // `responseEncoding` indicates encoding to use for decoding responses
  // Note: Ignored for `responseType` of 'stream' or client-side requests
  responseEncoding: 'utf8', // default

  // `xsrfCookieName` is the name of the cookie to use as a value for xsrf token
  xsrfCookieName: 'XSRF-TOKEN', // default

  // `xsrfHeaderName` is the name of the http header that carries the xsrf token value
  xsrfHeaderName: 'X-XSRF-TOKEN', // default

  // `onUploadProgress` allows handling of progress events for uploads
  onUploadProgress: function (progressEvent) {
    // Do whatever you want with the native progress event
  },

  // `onDownloadProgress` allows handling of progress events for downloads
  onDownloadProgress: function (progressEvent) {
    // Do whatever you want with the native progress event
  },

  // `maxContentLength` defines the max size of the http response content in bytes allowed
  maxContentLength: 2000,

  // `validateStatus` defines whether to resolve or reject the promise for a given
  // HTTP response status code. If `validateStatus` returns `true` (or is set to `null`
  // or `undefined`), the promise will be resolved; otherwise, the promise will be
  // rejected.
  validateStatus: function (status) {
    return status >= 200 && status < 300; // default
  },

  // `maxRedirects` defines the maximum number of redirects to follow in node.js.
  // If set to 0, no redirects will be followed.
  maxRedirects: 5, // default

  // `socketPath` defines a UNIX Socket to be used in node.js.
  // e.g. '/var/run/docker.sock' to send requests to the docker daemon.
  // Only either `socketPath` or `proxy` can be specified.
  // If both are specified, `socketPath` is used.
  socketPath: null, // default

  // `httpAgent` and `httpsAgent` define a custom agent to be used when performing http
  // and https requests, respectively, in node.js. This allows options to be added like
  // `keepAlive` that are not enabled by default.
  httpAgent: new http.Agent({ keepAlive: true }),
  httpsAgent: new https.Agent({ keepAlive: true }),

  // 'proxy' defines the hostname and port of the proxy server
  // Use `false` to disable proxies, ignoring environment variables.
  // `auth` indicates that HTTP Basic auth should be used to connect to the proxy, and
  // supplies credentials.
  // This will set an `Proxy-Authorization` header, overwriting any existing
  // `Proxy-Authorization` custom headers you have set using `headers`.
  proxy: {
    host: '127.0.0.1',
    port: 9000,
    auth: {
      username: 'mikeymike',
      password: 'rapunz3l'
    }
  },

  // `cancelToken` specifies a cancel token that can be used to cancel the request
  // (see Cancellation section below for details)
  cancelToken: new CancelToken(function (cancel) {
  })
}
```

## Response Schema (same as axios, typed with `AxiosResponse<T>` if using TypeScript)

The response for a request contains the following information.

```js
{
  // `data` is the response that was provided by the server
  data: {},

  // `status` is the HTTP status code from the server response
  status: 200,

  // `statusText` is the HTTP status message from the server response
  statusText: 'OK',

  // `headers` the headers that the server responded with
  // All header names are lower cased
  headers: {},

  // `config` is the config that was provided to `axios` for the request
  config: {},

  // `request` is the request that generated this response
  // It is the last ClientRequest instance in node.js (in redirects)
  // and an XMLHttpRequest instance the browser
  request: {}
}
```

## Config Defaults

You can specify config defaults that will be applied to every request.

### Global axios defaults

```js
Axios.defaults.baseURL = 'https://api.example.com';
Axios.defaults.headers.common['Authorization'] = AUTH_TOKEN;
Axios.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';
```

### Custom instance defaults

```js
// Set config defaults when creating the instance
const instance = Axios.create({
  baseURL: 'https://api.example.com'
});

// Alter defaults after instance has been created
instance.defaults.headers.common['Authorization'] = AUTH_TOKEN;
```

### Config order of precedence

Config will be merged with an order of precedence. The order is library defaults found in [lib/defaults.js](https://github.com/axios/axios/blob/master/lib/defaults.js#L28), then `defaults` property of the instance, and finally `config` argument for the request. The latter will take precedence over the former. Here's an example.

```js
// Create an instance using the config defaults provided by the library
// At this point the timeout config value is `0` as is the default for the library
const instance = Axios.create();

// Override timeout default for the library
// Now all requests using this instance will wait 2.5 seconds before timing out
instance.defaults.timeout = 2500;

// Override timeout for this request as it's known to take a long time
instance.get('/longRequest', {
  timeout: 5000
});
```

## Interceptors

You can intercept requests or responses before they are handled by `then` or `catch`.

```js
// Add a request interceptor
Axios.interceptors.request.use(function (config) {
    // Do something before request is sent
    return config;
  }, function (error) {
    // Do something with request error
    return Promise.reject(error);
  });

// Add a response interceptor
Axios.interceptors.response.use(function (response) {
    // Do something with response data
    return response;
  }, function (error) {
    // Do something with response error
    return Promise.reject(error);
  });
```

If you may need to remove an interceptor later you can.

```js
const myInterceptor = Axios.interceptors.request.use(function () {/*...*/});
Axios.interceptors.request.eject(myInterceptor);
```

You can add interceptors to a custom instance of axios.

```js
const instance = Axios.create();
instance.interceptors.request.use(function () {/*...*/});
```



You can define a custom HTTP status code error range using the `validateStatus` config option.

```js
Axios.get('/user/12345', {
  validateStatus: function (status) {
    return status < 500; // Reject only if the status code is greater than or equal to 500
  }
})
```

## Cancellation (Big win for axios-observable)
As opposed to axios which using cancel token, rxjs comes with a more natural way - unsubscribe


```js

const subscription = Axios.get('/user/12345').subscribe(response => console.log(response));

subscription.unsubscribe();
```

## Using application/x-www-form-urlencoded format

By default, axios serializes JavaScript objects to `JSON`. To send data in the `application/x-www-form-urlencoded` format instead, you can use one of the following options.

### Browser

In a browser, you can use the [`URLSearchParams`](https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams) API as follows:

```js
const params = new URLSearchParams();
params.append('param1', 'value1');
params.append('param2', 'value2');
Axios.post('/foo', params);
```

> Note that `URLSearchParams` is not supported by all browsers (see [caniuse.com](http://www.caniuse.com/#feat=urlsearchparams)), but there is a [polyfill](https://github.com/WebReflection/url-search-params) available (make sure to polyfill the global environment).

Alternatively, you can encode data using the [`qs`](https://github.com/ljharb/qs) library:

```js
const qs = require('qs');
Axios.post('/foo', qs.stringify({ 'bar': 123 }));
```

Or in another way (ES6),

```js
import qs from 'qs';
const data = { 'bar': 123 };
const options = {
  method: 'POST',
  headers: { 'content-type': 'application/x-www-form-urlencoded' },
  data: qs.stringify(data),
  url,
};
Axios.request(options);
```

### Node.js

In node.js, you can use the [`querystring`](https://nodejs.org/api/querystring.html) module as follows:

```js
const querystring = require('querystring');
Axios.post('http://something.com/', querystring.stringify({ foo: 'bar' }));
```

You can also use the [`qs`](https://github.com/ljharb/qs) library.

## TypeScript
axios-observable includes [TypeScript](http://typescriptlang.org) definitions.
```typescript
import Axios from 'axios-observable';
// or import {Axios} from 'axios-observable';
Axios.get('/user?ID=12345');
```


## License

MIT