# react-native-fetch-blob [![npm version](https://badge.fury.io/js/react-native-fetch-blob.svg)](https://badge.fury.io/js/react-native-fetch-blob)

A react-native module for fetch file/image with custom headers, supports blob response data.

If you're dealing with image or file server that requires an `Authorization` token in the header, or you're having problem with `fetch` API when receiving blob data, you might try this module (this is also the reason why I made this).

See [[fetch] Does fetch with blob() marshal data across the bridge?](https://github.com/facebook/react-native/issues/854).

This module enables you upload/download binary data in js, see [Examples](#user-content-usage) bellow.

The source code is very simple, just an implementation of native HTTP request, supports both Android (uses awesome native library  [AsyncHttpClient](https://github.com/AsyncHttpClient/async-http-client])) and IOS.

## Usage

* [Installation](#user-content-installation)
* [Examples](#user-content-usage)
 * [Download file](#user-content-download-example--fetch-files-that-needs-authorization-token)
 * [Upload file](#user-content-upload-example--dropbox-files-upload-api)
 * [Multipart/form upload](#user-content-multipartform-data-example--post-form-data-with-file-and-data)
* [API](#user-content-api)
* [Test and Development](#user-content-test-and-development)
* [Milestones](#user-content-milestones)

## Installation

Install package from npm

```sh
npm install --save react-native-fetch-blob
```

Link package using [rnpm](https://github.com/rnpm/rnpm)

```sh
rnpm link
```

## Usage

```js
import RNFetchBlob from 'react-native-fetch-blob'
```
#### Download example : Fetch files that needs authorization token

```js

// send http request in a new thread (using native code)
RNFetchBlob.fetch('GET', 'http://www.example.com/images/img1.png', {
    Authorization : 'Bearer access-token...',
    // more headers  ..
  })
  // when response status code is 200
  .then((res) => {
    // the conversion is done in native code
    let base64Str = res.base64()
    // the following conversions are done in js, it's SYNC
    let text = res.text()
    let json = res.json()

  })
  // Status code is not 200
  .catch((errorMessage, statusCode) => {
    // error handling
  })
```

####  Upload example : Dropbox [files-upload](https://www.dropbox.com/developers/documentation/http/documentation#files-upload) API

`react-native-fetch-blob` will convert the base64 string in `body` to binary format using native API, this process will be  done in a new thread, so it's async.

```js

RNFetchBlob.fetch('POST', 'https://content.dropboxapi.com/2/files/upload', {
    Authorization : "Bearer access-token...",
    'Dropbox-API-Arg': JSON.stringify({
      path : '/img-from-react-native.png',
      mode : 'add',
      autorename : true,
      mute : false
    }),
    'Content-Type' : 'application/octet-stream',
  }, base64ImageString)
  .then((res) => {
    console.log(res.text())
  })
  .catch((err) => {
    // error handling ..
  })
```

#### Multipart/form-data example : Post form data with file and data

In `version >= 0.3.0` you can also post files with form data,  just put an array in `body`, with object elements with property `name`, `data`, and `filename`(optional).

Elements have property `filename` will be transformed into binary format, otherwise it turns into utf8 string.

```js

  RNFetchBlob.fetch('POST', 'http://www.example.com/upload-form', {
    Authorization : "Bearer access-token",
    otherHeader : "foo",
    'Content-Type' : 'multipart/form-data',
  }, [
    // element with property `filename` will be transformed into `file` in form data
    { name : 'avatar', filename : 'avatar.png', data: binaryDataInBase64},
    // elements without property `filename` will be sent as plain text
    { name : 'name', data : 'user'},
    { name : 'info', data : JSON.stringify({
      mail : 'example@example.com',
      tel : '12345678'
    })},
  ]).then((resp) => {
    // ...
  }).catch((err) => {
    // ...
  })
```

## API

#### `fetch(method, url, headers, body):Promise<FetchBlobResponse> `

Send a HTTP request uses given headers and body, and return a Promise.

#### method:`string` Required
HTTP request method, can be one of `get`, `post`, `delete`, and `put`, case-insensitive.
#### url:`string` Required
HTTP request destination url.
#### headers:`object` (Optional)
Headers of HTTP request, value of headers should be `stringified`, if you're uploading binary files, content-type should be `application/octet-stream` or `multipart/form-data`(see examples above).
#### body:`string | Array<Object>` (Optional)
Body of the HTTP request, body can either be a BASE64 string, or an array contains object elements, each element have 2  required property `name`, and `data`, and 1 optional property `filename`, once `filename` is set, content in `data` property will be consider as BASE64 string that will be converted into byte array later.

When body is a base64 string , this string will be converted into byte array in native code, and the request body will be sent as `application/octet-stream`.

#### `base64`

A helper object simply uses [base-64](https://github.com/mathiasbynens/base64) for decode and encode BASE64 data.

```js
RNFetchBlob.base64.encode(data)
RNFetchBlob.base64.decode(data)
```

### FetchBlobResponse

When `fetch` success, it resolve a `FetchBlobResponse` object as first argument. `FetchBlobResponse` object has the following methods (these method are synchronous, so you might take quite a performance impact if the file is big)

#### base64():string
  returns base64 string of response data (done in native context)
#### json():object
  returns json parsed object (done in js context)
#### text():string
  returns decoded base64 string (done in js context)


### Test and Development

Check our [development guide](https://github.com/wkh237/react-native-fetch-blob/wiki/Development-Guide)

### Milestones

[V0.5 milestone](https://github.com/wkh237/react-native-fetch-blob/milestones/v0.5)

* Save file to storage directly
* Custom MIME type in form data
* Upload/Download progress report