rn-fetch-blob

react-native-fetch-blob

v0.5.0 Work In Progress README.md

A react-native module for upload, and download file with custom headers. Supports blob response data, upload/download progress, and file reader API that enables you process file content in js context (such as display image data, string or image process).

If you’re dealing with image or file server that requires special field in the header, or you’re having problem with fetch API when receiving blob data, you might try this module.

See [fetch] Does fetch with blob() marshal data across the bridge? for the reason why we made this module.

In latest version (v0.5.0), you can upload/download files directly with file path. We’ve also introduced file stream API for reading large files from storage, see Examples bellow.

This module implements native HTTP request, supports both Android (uses awesome native library AsyncHttpClient) and IOS.

Usage

• Installation
• Examples
  • Download file
  • Upload file
  • Multipart/form upload
  • Upload/Download progress
  • Deal with files in storage
  • Release cache files
• API

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

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

Download to storage directly

If you want to save the response data directly into file storage rather than convert response data into base64 for some reason.

Put a config before calling fetch. There’re three options which are path, fileCache, and appendExt that let you decide how and where to save the file.

The simplest way is give a fileCach option to config, and set it to true. This will let the incoming response data stored in a temporary path wihout any file extension.

RNFetchBlob
  .config({
    fileCache : true,
  })
  .fetch('GET', 'http://www.example.com/file/example.zip', {
    some headers ..
  })
  .then((res) => {
    // the temp file path
    console.log('The file saved to ', res.path())
  })

But in some cases, you might need a file extension even the file is temporary cached. For instance, when use the file path as source of Image element the path should end with something like .png or .jpg, you can do this by put one more option in to config.

RNFetchBlob
  .config({
    fileCache : true,
    appendExt : 'png'
  })
  .fetch('GET', 'http://www.example.com/file/example.zip', {
    some headers ..
  })
  .then((res) => {
    // the temp file path with file extension `png`
    console.log('The file saved to ', res.path())
    // Beware that when using a file path as Image source on Android,
    // you must prepend "file://"" before the file path
    imageView = <Image source={{ uri : Platform.OS === 'android' ? 'file://' : '' + res.path() }}/>
  })

What’s more, if you prefer a specific path, rather a random generated path, you can use path option. We’ve added a getSystemDirs API in v0.5.0 that lists several common used directories.

RNFetchBlob.getSystemDirs().then((dirs) => {
  RNFetchBlob
    .config({
      path : dirs.DocumentDir + 'path-to-file.anything'
    })
    .fetch('GET', 'http://www.example.com/file/example.zip', {
      some headers ..
    })
    .then((res) => {
      // the path should be dirs.DocumentDir + 'path-to-file.anything'
      console.log('The file saved to ', res.path())
    })
})

Upload example : Dropbox 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.

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 ..
  })

Upload a file from storage

If you’re going to use a file in file system as request body, just push the path with prefix RNFetchBlob-file://.

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

What if some fields contains a file in file storage ? Just like upload a file from storage example, change the data to path of the file with a prefix RNFetchBlob-file://

  RNFetchBlob.fetch('POST', 'http://www.example.com/upload-form', {
    Authorization : "Bearer access-token",
    otherHeader : "foo",
    'Content-Type' : 'multipart/form-data',
  }, [
    // append field data from file path
    { name : 'avatar', filename : 'avatar.png', data: 'RNFetchBlob-file://' + PATH_TO_THE_FILE},
    // 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) => {
    // ...
  })

Upload/Download progress

In version >= 0.4.2 it is possible to know the upload/download progress.

  RNFetchBlob.fetch('POST', 'http://www.example.com/upload', {
      ... some headers,
      'Content-Type' : 'octet-stream'
    }, base64DataString)
    .progress((received, total) => {
        console.log('progress', received / total)
    })
    .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.

fetch(...).progress(eventListener):Promise<FetchBlobResponse> added in 0.4.2

Register on progress event handler for a fetch request.

eventListener:(sendOrReceivedBytes:number, totalBytes:number)

A function that triggers when there’s data received/sent, first argument is the number of sent/received bytes, and second argument is expected total bytes number.

base64

A helper object simply uses base-64 for decode and encode BASE64 data.

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)

Major Changes

Version
~0.3.0	Upload/Download octet-stream and form-data
0.4.0	Add base-64 encode/decode library and API
0.4.1	Fixe upload form-data missing file extension problem on Android
0.4.2	Supports upload/download progress
0.5.0	Upload/download with direct access to file storage, and also supports read file with file stream

Upcoming Features

We are now working on v0.5.0, there will be some new features.

• Save file to storage directly
• Upload file from storage directly
• Custom MIME type in form data

Development

If you’re insterested in hacking this module, check our development guide, there might be something helpful. Please feel free to make a PR or file an issue.