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Download Files ​

  • In cloud functions, download files via await aircode.files.download(file, [options])
  • In the browser, download files using a third-party HTTP library

Download with _id ​

Because each uploaded file corresponds to a record in the _files data table, a file can be downloaded by specifying the value of its _id field. E.g:

js
const content = await aircode.files.download({
  // Replace the _id value with your file's
  _id: '63637d4807e4d5f7c24b195d'
});

const content = await aircode.files.download({
  // Replace the _id value with your file's
  _id: '63637d4807e4d5f7c24b195d'
});

The system will first look for the _id value from the _files table, and then obtain the file content by sending a request to the URL of the file.

Note

Please make sure that there is a record having the corresponding _id in the _files table, otherwise the download will fail.

Download with url ​

In addition to _id, you can also directly specify the URL address of the file to download it. E.g:

js
const content = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});

const content = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});

Tips

Each uploaded file will have a CDN-accelerated access address, which is stored in the url field of the _files table.

It should be noted that if _id and url are set at the same time, _id shall prevail.

Download as Buffer ​

By default, downloaded file content returns its binary data as a Buffer. E.g:

js
// Download the content as Buffer
const contentAsBuffer = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});
console.log('Buffer size:', contentAsBuffer.length);

// Download the content as Buffer
const contentAsBuffer = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});
console.log('Buffer size:', contentAsBuffer.length);

Tips

Buffer is a class provided by Node.js, which inherits from JavaScript's Unit8Array class. For more details, please refer to Node.js Doc.

When downloading as Buffer, the entire file content will be stored in memory. If the file size is too large, it may affect the running efficiency of the instance, or even cause memory overflow. Generally for files over 30 MB, it is recommended to Download as Stream.

Download as String Content ​

By setting dataType in the second parameter of the download function to 'string', the file content can be returned as a UTF-8 string, which is extremely convenient when downloading and processing text files. E.g:

js
// Download the content as UTF-8 string
const contentAsString = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  dataType: 'string',
});
console.log('The content of this text file is:', contentAsString);

// Download the content as UTF-8 string
const contentAsString = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  dataType: 'string',
});
console.log('The content of this text file is:', contentAsString);

If you want to get the text content in other encodings, you can download it as Buffer first, and then use the toString method to convert it. E.g:

js
// Download the content as Buffer
const contentAsBuffer = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});
// Then transform it to a latin string
const contentAsLatin = contentAsBuffer.toString('latin1');
console.log('The content as latin string is:', contentAsLatin);

// Download the content as Buffer
const contentAsBuffer = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
});
// Then transform it to a latin string
const contentAsLatin = contentAsBuffer.toString('latin1');
console.log('The content as latin string is:', contentAsLatin);

Download as Stream ​

When the downloaded file is large, we recommend downloading the file content as a data Stream. This can save memory when processing data and prevent memory overflow due to excessive content size. E.g:

js
const fs = require('node:fs');

// Download the content as Stream
const contentAsStream = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  dataType: 'stream'
});

// Handle stream events
contentAsStream.on('data', chunk => {
  console.log(`Received ${chunk.length} bytes of data`);
});
contentAsStream.on('end', () => {
  console.log('There will be no more data');
});

// Or pipe the stream into a local file
const localFile = fs.createWriteStream('/tmp/file.txt');
contentAsStream.pipe(localFile);

const fs = require('node:fs');

// Download the content as Stream
const contentAsStream = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  dataType: 'stream'
});

// Handle stream events
contentAsStream.on('data', chunk => {
  console.log(`Received ${chunk.length} bytes of data`);
});
contentAsStream.on('end', () => {
  console.log('There will be no more data');
});

// Or pipe the stream into a local file
const localFile = fs.createWriteStream('/tmp/file.txt');
contentAsStream.pipe(localFile);

Tips

Stream is a class provided by Node.js. For details, please refer to Node.js Doc.

Monitor ​

By passing an onProgress callback function to the second parameter, real-time progress can be monitored during the download process. E.g:

js
const content = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  onProgress: (percentage, remainSize) => {
    console.log(`Downloaded ${percentage}% of the file`);
    console.log(`Remain size: ${remainSize} bytes`);
  }
});

const content = await aircode.files.download({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt'
}, {
  onProgress: (percentage, remainSize) => {
    console.log(`Downloaded ${percentage}% of the file`);
    console.log(`Remain size: ${remainSize} bytes`);
  }
});

Download in Browser ​

The aircode.files.download method can only be called in cloud functions. If you want to download the binary data of the file and process it in the browser, you can use any HTTP library to send a GET request to get it.

Tips

Each uploaded file will have a CDN-accelerated access address, which is stored in the url field of the _files table.

For example, we use the axios library to get a file and set the return value to be of type ArrayBuffer:

js
import axios from 'axios';

axios({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt',
  method: 'GET',
  responseType: 'arraybuffer'
}).then(response => {
  console.log(`Downloaded ${response.data.byteLength} bytes of data`);
});

import axios from 'axios';

axios({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt',
  method: 'GET',
  responseType: 'arraybuffer'
}).then(response => {
  console.log(`Downloaded ${response.data.byteLength} bytes of data`);
});

If you want to download the file locally, you can set the return value to Blob type and use the third-party library js-file-download to download and save. E.g:

js
import axios from 'axios';
import fileDownload from 'js-file-download';

axios({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt',
  method: 'GET',
  responseType: 'blob'  // Important
}).then(response => {
  // Trigger browser to save data to file as if it was downloaded
  fileDownload(response.data, 'filename.txt');
});

import axios from 'axios';
import fileDownload from 'js-file-download';

axios({
  // Replace the url value with your file's
  url: 'https://sample.aircodecdn.com/hello.b10a8db164e07541.txt',
  method: 'GET',
  responseType: 'blob'  // Important
}).then(response => {
  // Trigger browser to save data to file as if it was downloaded
  fileDownload(response.data, 'filename.txt');
});