Listing Object Versions in a Bucket (SDK for Go)

Updated on 2024-06-21 GMT+08:00

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Function

This API returns some or all of the object versions in a bucket. You can use parameters such as the prefix, number of returned object versions, and start position to return the object versions that meet specified criteria. Returned object versions are listed in alphabetical order.

Restrictions

To list object versions in a bucket, you must be the bucket owner or have the required permission (obs:bucket:ListBucketVersions in IAM or ListBucketVersions in a bucket policy). For details, see Introduction to OBS Access Control, IAM Custom Policies, and Creating a Custom Bucket Policy.
The mapping between OBS regions and endpoints must comply with what is listed in Regions and Endpoints.

Method

func (obsClient ObsClient) ListVersions(input *ListVersionsInput) (output *ListVersionsOutput, err error)

Request Parameters

**Table 1** List of request parameters
Parameter	Type	Mandatory (Yes/No)	Description
input	*ListVersionsInput	Yes	Explanation: Input parameters for listing object versions in a bucket. For details, see Table 2.

**Table 2** ListVersionsInput
Parameter	Type	Mandatory (Yes/No)	Description
Bucket	string	Yes	Explanation: Bucket name Restrictions: A bucket name must be unique across all accounts and regions. A bucket name: Must be 3 to 63 characters long and start with a digit or letter. Lowercase letters, digits, hyphens (-), and periods (.) are allowed. Cannot be formatted as an IP address. Cannot start or end with a hyphen (-) or period (.). Cannot contain two consecutive periods (..), for example, my..bucket. Cannot contain a period (.) and a hyphen (-) adjacent to each other, for example, my-.bucket or my.-bucket. If you repeatedly create buckets of the same name in the same region, no error will be reported and the bucket attributes comply with those set in the first creation request. Default value: None
KeyMarker	string	No	Explanation: Object name to start with when listing object versions in a bucket. All object versions following the value specified by this parameter are listed in alphabetical order by object name. Restrictions: This parameter is only used for listing objects with multiple versions. Value range: Value of NextKeyMarker in the response body of the last request Default value: None
VersionIdMarker	string	No	Explanation: This parameter is used together with KeyMarker. Version ID you want to start listing from. All object versions following the value specified by this parameter are listed in alphabetical order by object name and version ID. KeyMarker specifies the object name, and VersionIdMarker specifies the version ID of the specified object. Restrictions: This parameter is only used for listing objects with multiple versions. If the object specified by KeyMarker does not have the version specified by VersionIdMarker, this parameter is invalid. Value range: Object version ID, that is, the value of NextVersionIdMarker in the response body of the last request Default value: None
Prefix	string	No	Explanation: Name prefix that the objects to be listed must contain Assume that you have the following objects: logs/day1, logs/day2, logs/day3, and ExampleObject.jpg. If you specify logs/ as the prefix, logs/day1, logs/day2, and logs/day3 will be returned. If you leave this parameter blank, all objects in the bucket will be returned. Value range: The value must contain 1 to 1,024 characters. Default value: None
MaxKeys	int	No	Explanation: The maximum number of objects returned in the response in alphabetical order Value range: The value ranges from 1 to 1000. If the specified value is beyond this range, only 1,000 objects are returned. Default value: 1000
Delimiter	string	No	Explanation: Object names are grouped by this parameter, which is often used with Prefix. If a prefix is specified, objects with the same string from the prefix to the first delimiter are grouped into one CommonPrefixes. If no prefix is specified, objects with the same string from the first character to the first delimiter are grouped into one CommonPrefixes. Assume that a bucket has objects abcd, abcde, and bbcde in it. If delimiter is set to d and prefix is set to a, objects abcd and abcde are grouped into a CommonPrefixes with abcd as the prefix. If only delimiter is set to d, objects abcd and abcde are grouped into a CommonPrefixes with abcd as the prefix, and bbcde is grouped separately into another CommonPrefixes with bbcd as the prefix. For a parallel file system, if this parameter is not specified, all the content in the current directory is recursively listed by default, and subdirectories are also listed. In big data scenarios, parallel file systems usually have deep directory levels and each directory has a large number of files. In such case, you are advised to configure [delimiter=/] to list the content in the current directory, but not list subdirectories, thereby improving the listing efficiency. Value range: The value must contain 1 to 1,024 characters. Default value: None
EncodingType	string	No	Explanation: Encoding type for some elements in the response. If Delimiter, KeyMarker, Prefix, CommonPrefixes, NextKeyMarker, and Key contain control characters that are not supported by the XML 1.0 standard, you can use EncodingType to encode Delimiter, KeyMarker, Prefix, CommonPrefixes, NextKeyMarker, and Key in the response. Value range: Value option: url Default value: None. If you leave this parameter blank, encoding is not applied to elements.

Responses

**Table 3** List of returned results
Parameter	Type	Description
output	*ListVersionsOutput	Explanation: Returned parameters for listing object versions in a bucket. For details, see Table 4.
err	error	Explanation: Error messages returned by the API

**Table 4** ListVersionsOutput
Parameter	Type	Description
StatusCode	int	Explanation: HTTP status code Value range: A status code is a group of digits that can be 2xx (indicating successes) or 4xx or 5xx (indicating errors). It indicates the status of a response. For more information, see Status Code. Default value: None
RequestId	string	Explanation: Request ID returned by the OBS server Default value: None
ResponseHeaders	map[string][]string	Explanation: HTTP response headers Default value: None
Location	string	Explanation: Region where a bucket is located Restrictions: If the used endpoint is obs.myhuaweicloud.com, this parameter is not required. If any other endpoint is used, this parameter is required. Value range: To learn about valid regions and endpoints, see Regions and Endpoints. An endpoint is the request address for calling an API. Endpoints vary depending on services and regions. To obtain the regions and endpoints, contact the enterprise administrator. Default value: If obs.myhuaweicloud.com is used as the endpoint and no region is specified, cn-north-1 (the CN North-Beijing1 region) is used by default.
Name	string	Explanation: Bucket name Restrictions: A bucket name must be unique across all accounts and regions. A bucket name: Must be 3 to 63 characters long and start with a digit or letter. Lowercase letters, digits, hyphens (-), and periods (.) are allowed. Cannot be formatted as an IP address. Cannot start or end with a hyphen (-) or period (.). Cannot contain two consecutive periods (..), for example, my..bucket. Cannot contain a period (.) and a hyphen (-) adjacent to each other, for example, my-.bucket or my.-bucket. If you repeatedly create buckets of the same name in the same region, no error will be reported and the bucket attributes comply with those set in the first creation request. Value range: The value must contain 3 to 63 characters.
Prefix	string	Explanation: Object name prefix, which is consistent with that set in the request Assume that you have the following objects: logs/day1, logs/day2, logs/day3, and ExampleObject.jpg. If you specify logs/ as the prefix, logs/day1, logs/day2, and logs/day3 will be returned. If you leave this parameter blank, all objects in the bucket will be returned. Value range: The value must contain 1 to 1,024 characters. Default value: None
KeyMarker	string	Explanation: Object name to start listing from. All object versions following the value specified by this parameter are listed in alphabetical order by object name. Restrictions: This parameter is only used for listing objects with multiple versions. Value range: The value must contain 1 to 1,024 characters. Default value: None
VersionIdMarker	string	Explanation: Version ID of the object specified by keyMarker. This parameter is used together with KeyMarker. All object versions following the value specified by this parameter are listed in alphabetical order by object name and version ID. KeyMarker specifies the object name, and VersionIdMarker specifies the version ID of the specified object. Restrictions: This parameter is only used for listing objects with multiple versions. If the object specified by KeyMarker does not have the version specified by VersionIdMarker, this parameter is invalid. Value range: The value must contain 32 characters. Default value: None
Delimiter	string	Explanation: Object names are grouped by this parameter, which is often used with Prefix. If a prefix is specified, objects with the same string from the prefix to the first delimiter are grouped into one CommonPrefixes. If no prefix is specified, objects with the same string from the first character to the first delimiter are grouped into one CommonPrefixes. Assume that a bucket has objects abcd, abcde, and bbcde in it. If delimiter is set to d and prefix is set to a, objects abcd and abcde are grouped into a CommonPrefixes with abcd as the prefix. If only delimiter is set to d, objects abcd and abcde are grouped into a CommonPrefixes with abcd as the prefix, and bbcde is grouped separately into another CommonPrefixes with bbcd as the prefix. For a parallel file system, if this parameter is not specified, all the content in the current directory is recursively listed by default, and subdirectories are also listed. In big data scenarios, parallel file systems usually have deep directory levels and each directory has a large number of files. In such case, you are advised to configure [delimiter=/] to list the content in the current directory, but not list subdirectories, thereby improving the listing efficiency. Value range: The value must contain 1 to 1,024 characters. Default value: None
MaxKeys	int	Explanation: Maximum number of objects to list The maximum number of objects returned in the response in alphabetical order Value range: The value ranges from 1 to 1000. If the specified value is beyond this range, only 1,000 objects are returned. Default value: 1000
IsTruncated	bool	Explanation: Whether all results are returned in the response. A maximum of 1,000 objects can be listed at a time. If the number of objects is greater than 1,000, the objects beyond 1,000 cannot be returned. Value range: true: Not all results are returned. false: All results are returned. Default value: None
NextKeyMarker	string	Explanation: Object name to start with in the next request for listing object versions Key marker for the last returned object in the list. NextKeyMarker is returned when not all the objects are listed. You can set KeyMarker to this value in the next request to list the remaining objects. Restrictions: This parameter is only used for listing objects with multiple versions. Value range: The value must contain 1 to 1,024 characters. Default value: None
NextVersionIdMarker	string	Explanation: Version ID to start with in the next request for listing object versions. It must be used together with NextKeyMarker. NextVersionIdMarker is returned when not all the objects are listed. You can set VersionIdMarker to this value in the next request to list the remaining objects. Restrictions: This parameter is only used for listing objects with multiple versions. Value range: The value must contain 32 characters. Default value: None
Versions	[]Version	Explanation: List of object versions in the bucket. For details, see Table 5.
DeleteMarkers	[]DeleteMarker	Explanation: List of delete markers in the bucket. For details, see Table 6.
CommonPrefixes	[]string	Explanation: List of object name prefixes grouped according to the Delimiter parameter (if specified) Value range: The value must contain 1 to 1,024 characters. Default value: None
EncodingType	string	Explanation: Encoding type for some elements in the response. If Delimiter, KeyMarker, Prefix, CommonPrefixes, NextKeyMarker, and Key contain control characters that are not supported by the XML 1.0 standard, you can use EncodingType to encode Delimiter, KeyMarker, Prefix, CommonPrefixes, NextKeyMarker, and Key in the response. Value range: Value option: url Default value: None

**Table 5** Version
Parameter	Type	Description
Key	string	Explanation: Object name. An object is uniquely identified by an object name in a bucket. An object name is a complete path that does not contain the bucket name. For example, if the address for accessing an object is examplebucket.obs.ap-southeast-1.myhuaweicloud.com/folder/test.txt, the object name is folder/test.txt. Value range: The value must contain 1 to 1,024 characters. Default value: None
VersionId	string	Explanation: Object version ID Value range: The value must contain 32 characters. Default value: None
LastModified	time.Time	Explanation: Time (UTC) when an object was last modified Value range: UTC time Default value: None
ETag	string	Explanation: Base64-encoded, 128-bit MD5 value of an object. ETag is the unique identifier of the object content. It can be used to determine whether the object content is changed. For example, if ETag value is A when an object is uploaded but changes to B when the object is downloaded, it indicates that the object content is changed. The ETag reflects changes to the object content, rather than the object metadata. An uploaded object or copied object has a unique ETag. Restrictions: If an object is encrypted using server-side encryption, the ETag is not the MD5 value of the object. Value range: The value must contain 32 characters. Default value: None
Size	int64	Explanation: Object size in bytes Value range: The value ranges from 0 TB to 48.8 TB, in bytes. Default value: None
Owner	Owner	Explanation: Object owner. For details, see Table 7.
StorageClass	StorageClassType	Explanation: Storage class of the object. For details, see Table 8.
IsLatest	bool	Explanation: Whether the object is of the current version Value range: true: The object is the latest version. false: The object is not the latest version. Default value: false

**Table 6** DeleteMarker
Parameter	Type	Description
Key	string	Explanation: Object name. An object is uniquely identified by an object name in a bucket. An object name is a complete path that does not contain the bucket name. For example, if the address for accessing the object is examplebucket.obs.ap-southeast-1.myhuaweicloud.com/folder/test.txt, the object name is folder/test.txt. Value range: The value must contain 1 to 1,024 characters. Default value: None
VersionId	string	Explanation: Object version ID Value range: The value must contain 32 characters. Default value: None
IsLatest	bool	Explanation: Whether the object is of the current version Value range: true: The object is the latest version. false: The object is not the latest version. Default value: false
LastModified	time.Time	Explanation: Time (UTC) when an object was last modified Value range: UTC time Default value: None
Owner	Owner	Explanation: Object owner. This parameter contains the domain ID and name of the object owner. For details, see Table 7.
StorageClass	StorageClassType	Explanation: Object storage class Value range: For details about storage classes, see Table 8. Default value: None

**Table 7** Owner
Parameter	Type	Mandatory (Yes/No)	Description
ID	string	Yes if used as a request parameter	Explanation: Account (domain) ID of the owner Value range: To obtain the account ID, see How Do I Get My Account ID and User ID? Default value: None

**Table 8** StorageClassType
Constant	Default Value	Description
StorageClassStandard	STANDARD	OBS Standard Features low access latency and high throughput and is used for storing massive, frequently accessed (multiple times a month) or small objects (< 1 MB) requiring quick response.
StorageClassWarm	WARM	OBS Infrequent Access Used for storing data that is semi-frequently accessed (fewer than 12 times a year) but is instantly available when needed.
StorageClassCold	COLD	OBS Archive Used for storing rarely accessed (once a year) data.

Code Examples

This example returns object versions in bucket examplebucket.

    
     
       
       package main
import (
    "fmt"
    "os"
    obs "github.com/huaweicloud/huaweicloud-sdk-go-obs/obs"
)
func main() {
    //Obtain an AK/SK pair using environment variables or import an 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.
    ak := os.Getenv("AccessKeyID")
    sk := os.Getenv("SecretAccessKey")
    // (Optional) If you use a temporary AK/SK pair and a security token to access OBS, you are advised not to use hard coding to reduce leakage risks. You can obtain an AK/SK pair using environment variables or import an AK/SK pair in other ways.
    // securityToken := os.Getenv("SecurityToken")
    // Enter the endpoint corresponding to the bucket. CN-Hong Kong is used here as an example. Replace it with the one currently in use.
    endPoint := "https://obs.ap-southeast-1.myhuaweicloud.com"
    // Create an obsClient instance.
    // If you use a temporary AK/SK pair and a security token to access OBS, use the obs.WithSecurityToken method to specify a security token when creating an instance.
    obsClient, err := obs.New(ak, sk, endPoint/*, obs.WithSecurityToken(securityToken)*/)
    if err != nil {
        fmt.Printf("Create obsClient error, errMsg: %s", err.Error())
    }
    input := &obs.ListVersionsInput{}
    // Specify a bucket name.
    input.Bucket = "examplebucket"
    // Specify an object prefix (test/ as an example). Objects whose names contain the specified prefix will be listed.
    input.Prefix = "test/"
    // Specify the maximum number of objects to be returned. 100 is used as an example. Returned objects are listed in alphabetic order. The default value is 1000.
    input.MaxKeys = 100
    // Specify the position (test/test2 as an example) where the version listing starts.
    input.KeyMarker = "test/test2"
    // VersionIdMarker must be used together with KeyMarker. If there is no VersionIdMarker mapping to the specified KeyMarker, ignore VersionIdMarker.
    input.VersionIdMarker = "G001117FCE89978B0000401205D5DC9A"
    // Specify an encoding type. url is used as an example. If the objects to list contain special characters, this parameter must be passed.
    input.EncodingType = "url"
    // List object versions in the bucket.
    output, err := obsClient.ListVersions(input)
    if err == nil {
        fmt.Printf("List version objects under the bucket(%s) successful!\n", input.Bucket)
        fmt.Printf("RequestId:%s\n", output.RequestId)
        for index, val := range output.Versions {
            fmt.Printf("Version[%d]-OwnerId:%s, ETag:%s, Key:%s, VersionId:%s, LastModified:%s, Size:%d\n",
                index, val.Owner.ID, val.ETag, val.Key, val.VersionId, val.LastModified, val.Size)
        }
        for index, val := range output.DeleteMarkers {
            fmt.Printf("DeleteMarker[%d]-OwnerId:%s, Key:%s, VersionId:%s, LastModified:%s\n",
                index, val.Owner.ID, val.Key, val.VersionId, val.LastModified)
        }
        return
    }
    fmt.Printf("List version objects under the bucket(%s) fail!\n", input.Bucket)
    if obsError, ok := err.(obs.ObsError); ok {
        fmt.Println("An ObsError was found, which means your request sent to OBS was rejected with an error response.")
        fmt.Println(obsError.Error())
    } else {
        fmt.Println("An Exception was found, which means the client encountered an internal problem when attempting to communicate with OBS, for example, the client was unable to access the network.")
        fmt.Println(err)
    }
}

      

    
   

Helpful Links

Parent topic: Buckets (SDK for Go)

Previous topic: Listing Objects in a Bucket (SDK for Go)

Next topic: Obtaining Bucket Metadata (SDK for Go)

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