rn-fetch-blob

react-native-fetch-blob []()

A module provides upload, download, and files access API. Supports file stream read/write for process large files.

Why do we need this

React Native does not support Blob object at this moment, which means if you’re going to send/receive binary data via fetch API, that might not work as you expect. See facebook/react-native#854.

For some use cases, you might get into trouble. For example, displaying an image that requires a specific field in headers (ex. “Authorization : Bearer …”) or body, so you can’t just pass the image uri to Image component because that will probably returns a 401 response. Or you’re going to upload binary data which generated from JS, the server will get an empry body due to this issue. With help of APIs provided by this module, you can send HTTP request with any headers, and decide how to handle the response/reqeust data without worry about if it is not supported by fetch API. The response data can be just simply converted into BASE64 string, or stored to a file directly so that you can read it by using file access APIs such as readFile, readStream.

This module was designed to be a substitution of Blob, there’s a set of APIs including basic file system CRUD method, and file stream reader/writer. Also it has a special fetch implementation that supports binary request/response body.

Backward Compatible

All updates are backward-compatible generally you don’t have to change existing code unless you’re going to use new APIs. But we recommend pre 0.5.0 users consider upgrade the package to latest version, since we have introduced new APIs can either upload or download files simply using a file path. It’s much more memory efficent in some use case. We’ve also introduced fs APIs for access files, and file stream API that helps you read/write files (especially for large ones), see Examples bellow. This module implements native methods, supports both Android (uses awesome native library AsyncHttpClient) and IOS.

TOC

• Installation
• Recipes
  • Download file
  • Upload file
  • Multipart/form upload
  • Upload/Download progress
  • Android Media Scanner, and Download Manager Support
  • File access
  • File stream
  • Manage cached files
  • Self-Signed SSL Server
• API References
• Development

Installation

Install package from npm

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

Link package using rnpm

rnpm link

Grant Permission to External storage for Android 5.0 or lower

Mechanism about granting Android permissions has slightly different since Android 6.0 released, please refer to Officail Document.

If you’re going to access external storage (say, SD card storage) for Android 5.0 (or lower) devices, you might have to add the following line to AndroidManifetst.xml.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rnfetchblobtest"
    android:versionCode="1"
    android:versionName="1.0">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
+   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />                                               
+   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />                                              

    ...

Also, if you’re going to use Android Download Manager you have to add this to AndroidManifetst.xml

    <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
+           <action android:name="android.intent.action.DOWNLOAD_COMPLETE"/>                          
    </intent-filter>

Grant Access Permission for Android 6.0

Beginning in Android 6.0 (API level 23), users grant permissions to apps while the app is running, not when they install the app. So adding permissions in AndroidManifest.xml won’t work in Android 6.0 devices. To grant permissions in runtime, you might use modules like react-native-android-permissions.

Recipes

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

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.

These files won’t be removed automatically, please refer to Cache File Management

RNFetchBlob
  .config({
    // add this option that makes response data to be stored as a file,
    // this is much more performant.
    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())
  })

Set Temp File Extension

Sometimes you might need a file extension for some reason. For instance, when using file path as source of Image component, the path should end with something like .png or .jpg, you can do this by add appendExt option to config.

RNFetchBlob
  .config({
    fileCache : true,
    // by adding this option, the temp files will have a file extension
    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() }}/>
  })

Use Specific File Path

If you prefer a specific path rather than random generated one, you can use path option. We’ve added a constant dirs in v0.5.0 that contains several common used directories.

let dirs = RNFetchBlob.fs.dirs
RNFetchBlob
.config({
  // response data will be saved to this path if it has access right.
  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())
})

These files won’t be removed automatically, please refer to Cache File Management

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',
    // here's the body you're going to send, should be a BASE64 encoded string
    // (you can use "base64" APIs to make one).
    // The data will be converted to "byte array"(say, blob) before request sent.  
  }, base64ImageString)
  .then((res) => {
    console.log(res.text())
  })
  .catch((err) => {
    // error handling ..
  })

Upload a file from storage

If you’re going to use a file request body, just wrap the path with wrap API.

RNFetchBlob.fetch('POST', 'https://content.dropboxapi.com/2/files/upload', {
    // dropbox upload headers
    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',
    // Change BASE64 encoded data to a file path with prefix `RNFetchBlob-file://`.
    // Or simply wrap the file path with RNFetchBlob.wrap().
  }, RNFetchBlob.wrap(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 elements have 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 you want to upload a file in some field ? Just like upload a file from storage example, wrap data by wrap API (this feature is only available for version >= v0.5.0)

  RNFetchBlob.fetch('POST', 'http://www.example.com/upload-form', {
    Authorization : "Bearer access-token",
    otherHeader : "foo",
    // this is required, otherwise it won't be process as a multipart/form-data request
    'Content-Type' : 'multipart/form-data',
  }, [
    // append field data from file path
    {
      name : 'avatar',
      filename : 'avatar.png',
      // Change BASE64 encoded data to a file path with prefix `RNFetchBlob-file://`.
      // Or simply wrap the file path with RNFetchBlob.wrap().
      data: RNFetchBlob.wrap(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) => {
      // ...
    })

Android Media Scanner, and Download Manager Support

If you want to make a file in External Storage becomes visible in Picture, Downloads, or other built-in apps, you will have to use Media Scanner or Download Manager.

Media Scanner

Media scanner scan the file and categorize by given MIME type, if MIME type not specified, it will try to resolve the file using its file extension.

RNFetchBlob
    .config({
        // DCIMDir is in external storage
        path : dirs.DCIMDir + '/music.mp3'
    })
    .fetch('GET', 'http://example.com/music.mp3')
    .then((res) => RNFetchBlob.fs.scanFile([ { path : res.path(), mime : 'audio/mpeg' } ]))
    .then(() => {
        // scan file success
    })
    .catch((err) => {
        // scan file error
    })

Download Manager

When download large files on Android it is recommended to use Download Manager, it supports lot of native features like progress bar, and notification, also the download task will be handled by OS, and more effective.

When using DownloadManager, fileCache and path properties in config will not take effect, because Android DownloadManager can only store files to external storage. When download complete, DownloadManager will generate a file path so that you can deal with it.

RNFetchBlob
    .config({
        addAdnroidDownloads : {
            useDownloadManager : true, // <-- this is the only thing required
            // Optional, override notification setting (default to true)
            notification : false,
            // Optional, but recommended since android DownloadManager will fail when
            // the url does not contains a file extension, by default the mime type will be text/plain
            mime : 'text/plain',
            description : 'File downloaded by download manager.'
        }
    })
    .fetch('GET', 'http://example.com/file/somefile')
    .then((resp) => {
      // the path of downloaded file
      resp.path()
    })

Download Notification and Visibiliy in Download App (Android Only)

If you want to display a notification when file’s completely download to storage (as the above), or make the downloaded file visible in “Downloads” app. You have to add some options to config.

RNFetchBlob.config({
  fileCache : true,
  // android only options, these options be a no-op on IOS
  addAndroidDownloads : {
    // Show notification when response data transmitted
    notification : true,
    // Title of download notification
    title : 'Great ! Download Success ! :O ',
    // File description (not notification description)
    description : 'An image file.',
    mime : 'image/png',
    // Make the file scannable  by media scanner
    meidaScannable : true,
  }
})
.fetch('GET', 'http://example.com/image1.png')
.then(...)

File Access

File access APIs were made when developing v0.5.0, which helping us write tests, and was not planned to be a part of this module. However I realized that, it’s hard to find a great solution to manage cached files, every one who use this moudle may need those APIs for there cases.

File Access APIs

• dirs
• createFile
• writeFile (0.6.0)
• appendFile (0.6.0)
• readFile (0.6.0)
• readStream
• writeStream
• unlink
• mkdir
• ls
• mv
• cp
• exists
• isDir
• stat
• lstat
• scanFile (Android only)

See File API for more information

File Stream

In v0.5.0 we’ve added writeStream and readStream, which allows your app read/write data from file path. This API creates a file stream, rather than convert whole data into BASE64 encoded string, it’s handy when processing large files.

When calling readStream method, you have to open the stream, and start to read data.

let data = ''
RNFetchBlob.fs.readStream(
    // encoding, should be one of `base64`, `utf8`, `ascii`
    'base64',
    // file path
    PATH_TO_THE_FILE,
    // (optional) buffer size, default to 4096 (4095 for BASE64 encoded data)
    // when reading file in BASE64 encoding, buffer size must be multiples of 3.
    4095)
.then((ifstream) => {
    ifstream.open()
    ifstream.onData((chunk) => {
      // when encoding is `ascii`, chunk will be an array contains numbers
      // otherwise it will be a string
      data += chunk
    })
    ifstream.onError((err) => {
      console.log('oops', err)
    })
    ifstream.onEnd(() => {  
      <Image source={{ uri : 'data:image/png,base64' + data }}
    })
})

When use writeStream, the stream is also opened immediately, but you have to write, and close by yourself.

RNFetchBlob.fs.writeStream(
    PATH_TO_FILE,
    // encoding, should be one of `base64`, `utf8`, `ascii`
    'utf8',
    // should data append to existing content ?
    true)
.then((ofstream) => {
    ofstream.write('foo')
    ofstream.write('bar')
    ofstream.close()
})

Cache File Management

When using fileCache or path options along with fetch API, response data will automatically stored into file system. The files will NOT removed unless you unlink it. There’re several ways to remove the files

  // remove file using RNFetchblobResponse.flush() object method
  RNFetchblob.config({
      fileCache : true
    })
    .fetch('GET', 'http://example.com/download/file')
    .then((res) => {
      // remove cached file from storage
      res.flush()
    })

  // remove file by specifying a path
  RNFetchBlob.fs.unlink('some-file-path').then(() => {
    // ...
  })

You can also grouping requests by using session API, and use dispose to remove them all when needed.

  RNFetchblob.config({
    fileCache : true
  })
  .fetch('GET', 'http://example.com/download/file')
  .then((res) => {
    // set session of a response
    res.session('foo')
  })  

  RNFetchblob.config({
    // you can also set session beforehand
    session : 'foo'
    fileCache : true
  })
  .fetch('GET', 'http://example.com/download/file')
  .then((res) => {
    // ...
  })  

  // or put an existing file path to the session
  RNFetchBlob.session('foo').add('some-file-path')
  // remove a file path from the session
  RNFetchBlob.session('foo').remove('some-file-path')
  // list paths of a session
  RNFetchBlob.session('foo').list()
  // remove all files in a session
  RNFetchBlob.session('foo').dispose().then(() => { ... })

Self-Signed SSL Server

By default, react-native-fetch-blob does NOT allow connection to unknown certification provider since it’s dangerous. If you’re going to connect a server with self-signed certification, add trusty to config. This function is available for version >= 0.5.3

RNFetchBlob.config({
  trusty : true
})
.then('GET', 'https://mysite.com')
.then((resp) => {
  // ...
})

Changes

Version
0.6.1	Fix #37 progress report API issue on IOS
0.6.0	Add readFile and writeFile API for easier file access, also added Android download manager support.
0.5.8	Fix #33 PUT request will always be sent as POST on Android
0.5.7	Fix #31 #30 Xcode pre 7.3 build error
0.5.6	Add support for IOS network status indicator. Fix file stream ASCII reader bug.
0.5.5	Remove work in progress code added in 0.5.2 which may cause memory leaks.
0.5.4	Fix #30 #31 build build error, and improve memory efficiency.
0.5.3	Add API for access untrusted SSL server
0.5.2	Fix improper url params bug #26 and change IOS HTTP implementation from NSURLConnection to NSURLSession
0.5.0	Upload/download with direct access to file storage, and also added file access APIs
0.4.2	Supports upload/download progress
0.4.1	Fix upload form-data missing file extension problem on Android
0.4.0	Add base-64 encode/decode library and API
~0.3.0	Upload/Download octet-stream and form-data

Development

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