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Downloading Objects
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Last updated: 2024-02-04 17:20:25
Downloading Objects
Last updated: 2024-02-04 17:20:25
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Overview

This document provides an overview of APIs and SDK code samples related to object downloads.
API
Operation
Description
Downloading an object
Downloads an object to the local file system.

Description

This API (GET Object) is used to get the content, in string format, of a specified file in a bucket.

Sample code

cos.getObject({
    Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
    Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
    Key: '1.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
}, function(err, data) {
    console.log(err || data.Body);
});
Getting file content with Range specified
cos.getObject({
    Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
    Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
    Key: '1.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
    Range: 'bytes=1-3', /*Optional*/
}, function(err, data) {
    console.log(err || data.Body);
});
Downloading an object (limiting single-URL speed):
Note:
For more information about the speed limits on object downloads, please see Single-URL Speed Limits.
cos.getObject({
    Bucket: 'examplebucket-1250000000', /* Required */
    Region: 'COS_REGION',     /* Bucket region. Required */
    Key: 'exampleobject', /* Required */
    Headers: {
      'x-cos-traffic-limit': 819200, // The speed range is 819200 to 838860800, that is 100 KB/s to 100 MB/s. If the value is not within this range, 400 will be returned.
    },
}, function(err, data) {
    console.log(err || data.Body);
});
Downloading an object (via getObjectUrl): 
cos.getObjectUrl({
    Bucket: 'examplebucket-1250000000', /* Your bucket name. Required. */
    Region: 'COS_REGION',  /* Bucket region, such as `ap-beijing`. Required. */
    Key: '1.jpg',  /* Object key stored in the bucket (such as `1.jpg` and `a/b/test.txt`). Required. */
    Sign: true
}, function (err, data) {
    if (err) return console.log(err);
    wx.downloadFile({
        url: data.Url, // The “url” domain name needs to be added to the download allowlist
        success (res) {
            console.log(res.statusCode, res.tempFilePath);
        },
        fail: function (err) {
            console.log(err);
        },
    });
});

Parameter description

Parameter
Description
Type
Required
Bucket
Bucket name in the format of BucketName-APPID
String
Yes
Region
Bucket region. For the enumerated values, please see Regions and Access Endpoints.
String
Yes
Key
Object key (object name), the unique ID of an object in a bucket. For more information, please see Object Overview.
String
Yes
ResponseContentType
Content-Type parameter in the response header
String
No
ResponseContentLanguage
Content-Language in the response header
String
No
ResponseExpires
Content-Expires in the response header
String
No
ResponseCacheControl
Cache-Control in the response header
String
No
ResponseContentDisposition
Content-Disposition in the response header
String
No
ResponseContentEncoding
Content-Encoding in the response header
String
No
Range
Byte range of the object as defined in RFC 2616. The range value must be in the format of bytes=first-last, where both first and last are offsets starting from 0. For example, bytes=0-9 means to download the first 10 bytes of the object. If this parameter is not specified, the entire object will be downloaded.
String
No
If-Modified-Since
If the object is modified after the specified time, the corresponding object metadata will be returned; otherwise, "304 (not modified)" will be returned.
String
No
If-Unmodified-Since
Required unmodified time. The object is downloaded only if it has not been modified since the specified time. Otherwise, 412 (precondition failed) will be returned.
String
No
IfMatch
Returns the object only if the ETag matches the specified content; otherwise, an HTTP 412 (Precondition Failed) status code is returned
String
No
IfNoneMatch
Returns the object only if the ETag does not match the specified content; otherwise, an HTTP 304 (Not Modified) status code is returned
String
No
VersionId
Version ID of the object to download
String
No
onProgress
Progress callback. The attributes of the response object progressData are as follows.
Function
No
- progressData.loaded
Size of the downloaded parts, in bytes
Number
No
- progressData.total
Size of the entire object, in bytes
Number
No
- progressData.speed
Download speed, in bytes/s
Number
No
- progressData.percent
Percentage of the file download progress; for example, 0.5 means 50% downloaded
Number
No

Callback function description

function(err, data) { ... }
Parameter
Description
Type
err
Object returned when an error (network error or service error) occurs. If the request is successful, this is null. For more information, see Error Codes.
Object
- statusCode
HTTP status code, such as 200, 403, and 404.
Number
- headers
Headers.
Object
data
Content returned when the request is successful. If the request fails, this parameter is empty.
Object
- statusCode
Returns an HTTP status code, such as 200, 304, 403, and 404
Number
- headers
Headers.
Object
- Cache-Control
Cache directives as defined in RFC 2616. It will be returned only if it is contained in the object metadata or specified through the request parameter.
String
- Content-Disposition
Filename as defined in RFC 2616. It will be returned only if it is contained in the object metadata or specified through the request parameter.
String
- ContentEncoding
Encoding format as defined in RFC 2616. It will be returned only if it is contained in the object metadata or specified through the request parameter.
String
- Expires
Cache expiration time as defined in RFC 2616. It will be returned only if it is contained in the object metadata or specified through the request parameter.
string
- x-cos-storage-class
Storage class of the object. For the enumerated values, such as STANDARD (default), STANDARD_IA, and ARCHIVE, please see Storage Class Overview.
Note: If this header is not returned, the storage class of the object is STANDARD.
String
- x-cos-meta-*
User-defined metadata
String
- NotModified
This attribute will be returned if the request contains IfModifiedSince. If the file has been modified, false will be returned. If not, true will be returned.
Boolean
- ETag
MD5 checksum of the object. The value of ETag can be used to check whether the object was corrupted during the upload.
Example: "09cba091df696af91549de27b8e7d0f6"
Note that double quotation marks are required at the beginning and the end.
String
- VersionId
Version ID of the uploaded object if versioning is enabled for its bucket. If versioning is not enabled, this parameter is not returned.
String
- Body
Returned file content. Uses the String format by default.
String
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