Checking Whether an Object Exists (SDK for Python)

Function

This API checks whether an object exists. If the returned HTTP status code is 200, the object exists. If the returned HTTP status code is 404, the object or bucket does not exist.

Restrictions

To check whether an object exists, you must be the bucket owner or have the required permission (obs:bucket:ListBucket in IAM or ListBucket in a bucket policy). For details, see Introduction to OBS Access Control, IAM Custom Policies, and Configuring an Object Policy.
The mapping between OBS regions and endpoints must comply with what is listed in Regions and Endpoints.

Method

ObsClient.headObject(bucketName, objectKey, versionId, extensionHeaders)

Request Parameters

**Table 1** List of request parameters
Parameter	Type	Mandatory (Yes/No)	Description
bucketName	str	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 with the same name in the same region, no error will be reported and the bucket properties comply with those set in the first creation request. Default value: None
objectKey	str	Yes	Object name 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	str	No	Explanation: Object version ID, for example, G001117FCE89978B0000401205D5DC9 Value range: The value must contain 32 characters. Default value: None. If this parameter is not specified, the latest version of the object is specified by default.
extensionHeaders	dict	No	Explanation: Extension headers Value range: See User-defined Headers (SDK for Python). Default value: None

Responses

**Table 2** List of returned results
Type	Description
GetResult	Explanation: SDK common results

**Table 3** GetResult
Parameter	Type	Description
status	int	Explanation: HTTP status code Value range: A status code is a group of digits indicating the status of a response. It ranges from 2xx (indicating successes) to 4xx or 5xx (indicating errors). For more information, see Status Code. Default value: None
reason	str	Explanation: Reason description Default value: None
errorCode	str	Explanation: Error code returned by the OBS server. If the value of status is less than 300, this parameter is left blank. Default value: None
errorMessage	str	Explanation: Error message returned by the OBS server. If the value of status is less than 300, this parameter is left blank. Default value: None
requestId	str	Explanation: Request ID returned by the OBS server Default value: None
indicator	str	Explanation: Error indicator returned by the OBS server Default value: None
hostId	str	Explanation: Requested server ID. If the value of status is less than 300, this parameter is left blank. Default value: None
resource	str	Explanation: Error source (a bucket or an object). If the value of status is less than 300, this parameter is left blank. Default value: None
header	list	Explanation: Response header list, composed of tuples. Each tuple consists of two elements, respectively corresponding to the key and value of a response header. Default value: None
body	object	Explanation: Result content returned after the operation is successful. If the value of status is larger than 300, this parameter is left blank. The value varies with the API being called. For details, see the sections "Bucket-Related APIs" and "Object-Related APIs". Default value: None

Sample Code

     try:
    resp = obs_client.headObject("bucketname","objectkey")

    if resp.status < 300:
        print("Object exists")
    elif resp.status == 404:
        error_code = dict(resp.header).get("error-code")
        if error_code is not None and error_code == "NoSuchKey":
            print("Object does not exist")
            print("errorCode:", error_code)
except Exception:
    import traceback
    print(traceback.format_exc())
 
 
  