Performing a Partial Download

If you have any questions during development, post them on the Issues page of GitHub. For details about parameters and usage of each API, see the API Reference.

When only partial data of an object is required, you can download data falling within a specific range. If the specified range is 0 to 1000, data at the zeroth to the thousandth bytes, 1001 bytes in total, will be returned. If the specified range is invalid, data of the whole object will be returned. Sample code is as follows:

// Import the OBS library.
// Use npm to install the client.
var ObsClient = require('esdk-obs-nodejs');
// Use the source code to install the client.
// var ObsClient = require('./lib/obs');

// Create an ObsClient instance.
var obsClient = new ObsClient({
       //Obtain an AK/SK pair using environment variables or import the AK/SK pair in other ways. Using hard coding may result in leakage.
       //Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/intl/en-us/usermanual-ca/ca_01_0003.html.
       access_key_id: process.env.ACCESS_KEY_ID,
       secret_access_key: process.env.SECRET_ACCESS_KEY,
       server : 'https://your-endpoint'
});

obsClient.getObject({
       Bucket : 'bucketname',
       Key : 'objectname',
       // Set the start position and end position for downloading.
       Range : 'bytes=0-1000'
}, (err, result) => {
       if(err){
              console.error('Error-->' + err);
       }else{
              console.log('Status-->' + result.CommonMsg.Status);
              if(result.CommonMsg.Status < 300 && result.InterfaceResult){
                   // Obtain the object content.
                   console.log('Object Content:'); 
                   console.log(result.InterfaceResult.Content.toString()); 
              }
       }
});

• Use the Range parameter to specify the download range in the "bytes=x-y" format.
• If the specified range is invalid (because the start or end position is set to a negative integer or the range is larger than the object length), data of the whole object will be returned.
• This download method also can be used to concurrently download parts of a large object. For details about the sample code, see concurrent-download-object-sample.