react-native-fetch-blob

Since react-native fetch API does not marshals Blob data in request/response body, I made this plugin which send/receive HTTP request/response that have Blob body content.

This plugin simply convert given base64 string into blob format and send the request in a new thread. The process is done in native code, it supports both Android (uses awesome library AsyncHttpClient) and IOS.

If you're dealing with image or file server that requires an Authorization token in the header, you might try this plugin (this is also the reason why I made this plugin), the source code is very simple, just an implementation of native HTTP request.

Installation

Install package from npm

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

Link package using rnpm

rnpm link

Usage

import RNFetchBlob from 'react-native-fetch-blob'

Download example : Fetch files that needs authorization token

// 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 blob = res.blob()
    let text = res.text()
    let json = res.json()

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

Upload example : Dropbox files-upload API

react-native-fetch-blob will convert the base64 string in body to binary format in native code.

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.

  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 sent as plain text
    { name : 'name', data : 'user'},
    { name : 'info', data : JSON.stringify({
      mail : 'example@example.com',
      tel : '12345678'
    })},
  ]).then((resp) => {
    // ...
  }).catch((err) => {
    // ...
  })

The above code will become something like this in your request body

--RNFetchBlob-79338624
Content-Disposition: form-data; name="avatar"; filename="avatar.png"
Content-Type: application/octet-stream
�PNG


IHDR
G���ʣIDATx�흋s���/Ծl���رӧmu괝�kڙ��{���Q��@@��JQ[j�TA���,�Z"�
���$…��	!B `_�ٲ�9���7����B��ݻ��w���s��u��F�6nr@��9 G��
�#r@��9 G@��9 G��
�#r@��9 G����9 Ǩ�����ᝲg�*������Z���$��������9�.�c�%��U�wn5�hO��{���@?�=@����?~Wvo^�"ő���"͏ޒ��*�r,=�f�$����-E���_���n�^ �Ҡ㞏}��Jq5�����Iv�5<\�1�ɖ��3���*1Z�����O?��
�K-�
--RNFetchBlob-79338624
Content-Disposition: form-data; name="name";
Content-Type: text/plain

user
--RNFetchBlob-79338624
Content-Disposition: form-data; name="info";
Content-Type: text/plain

{"mail" : "example@example.com", "tel" : "12345678"}
--RNFetchBlob-79338624--

API

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

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 should use the following format.

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.

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)

blob():Blob

returns Blob object (one in js context)

TODO

• Save file to storage
• Native async format conversion
• Custom MIME type in form data

I'm not very new to native module development in RN, if there's any problem, please feel free to contact with me :D