Overview

The SDK for WeChat Mini Program provides samples for calculating signatures and getting object URLs and pre-signed request URLs.

Signature Calculation

In all COS XML API requests, the authentication credential Authorization is required for all operations on private resources for COS to determine whether a request is valid.

There are two ways to use the authentication credential:

1. Put it in the header parameter; field name: authorization.
2. Put it in the URL parameter; field name: sign.

The COS.getAuthorization method is used to calculate the authentication credential (Authorization), which is the signing information used to verify the request validity.

Note：

It is recommended that this method is only used for frontend debugging but not in actual projects, as it may disclose keys.

Use case

Obtain the authentication credential for object download:

// You can obtain/manage SECRETID and SECRETKEY at https://console.cloud.tencent.com/cam/capi
var Authorization = COS.getAuthorization({
   SecretId: 'SECRETID',
   SecretKey: 'SECRETKEY',
   Method: 'get',
   Key: 'picture.jpg',
   Expires: 60,
   Query: {},
   Headers: {}
});

Parameter description

Parameter Name	Description	Type	Required
SecretId	User SecretId	String	No
SecretKey	User's SecretKey	String	Yes
Method	HTTP request method such as GET, POST, DELETE, or HEAD	String	Yes
Key	Object key (object name), a unique ID of an object in a bucket. If the request operation is to be performed on a file, this parameter is required and should be a filename. If the operation is on a bucket, this parameter should be left empty	String	No
Query	Query parameter object of the request	Object	No
Headers	Header parameter object of the request	Object	No
Expires	Signature expiration time in seconds. Default value: 900 seconds	Number	No

Returned value

The returned value is the calculated authentication credential string authorization.

Obtaining pre-signed URL used for requests

Upload Request Description

In a WeChat Mini Program, you can only upload files via the POST Object API. Getting a pre-signed URL is not applicable to this API. If you need to upload files by yourself, please refer to Uploading Directly Through a WeChat Mini Program.

Samples for download requests

Sample 1. Get an unsigned object URL

var url = cos.getObjectUrl({
   Bucket: 'examplebucket-1250000000',
   Region: 'ap-beijing',
   Key: 'picture.jpg',
   Sign: false
});

Sample 2. Get a signed object URL

var url = cos.getObjectUrl({
   Bucket: 'examplebucket-1250000000',
   Region: 'ap-beijing',
   Key: 'picture.jpg'
});

Sample 3. Get a signed URL through callback

Note：

If the signing process is asynchronous, you need to get the signed URL through a callback.

cos.getObjectUrl({
   Bucket: 'examplebucket-1250000000',
   Region: 'ap-beijing',
   Key: 'picture.jpg',
   Sign: false
}, function (err, data) {
   console.log(err || data.Url);
});

Sample 4. Specify the validity period of the link

cos.getObjectUrl({
   Bucket: 'examplebucket-1250000000',
   Region: 'ap-beijing',
   Key: 'picture.jpg',
   Sign: true,
   Expires: 3600, // Unit: second
}, function (err, data) {
   console.log(err || data.Url);
});

Sample 5. Get an object URL and download the object

cos.getObjectUrl({
   Bucket: 'examplebucket-1250000000',
   Region: 'ap-beijing',
   Key: 'picture.jpg',
   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 whitelist
       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), a unique ID of an object in a bucket. If the request operation is to be performed on a file, this parameter is required and should be a filename. If the operation is on a bucket, this parameter should be left empty	String	Yes
Sign	Whether to return a signed URL. Default value: true	Boolean	No
Protocol	It can be http: (default) or https:	String	No
Domain	Bucket access domain. Default value: {BucketName-APPID}.cos.{Region}.myqcloud.com	String	No
Method	HTTP request method such as GET, POST, DELETE, or HEAD. Default value: GET	String	No
Query	Query parameter object used in the signature calculation	Object	No
Headers	Header parameter object used in the signature calculation	Object	No
Expires	Signature expiration time in seconds. Default value: 900 seconds	Number	No

Returned value description

The returned value is a string. There are two possible scenarios:

1. If the signature can be calculated synchronously (for example, the SecretId and SecretKey have been passed in during instantiation), the signed URL will be returned by default.
2. Otherwise; a URL without a signature will be returned.

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
data	Object returned when the request is successful. If the request fails, this parameter is left empty.	Object
- Url	Calculated URL	String