Object Storage Service:Append upload

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions, endpoints and open ports.

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Initialization.

• To use append upload, you must have the oss:PutObject permission. For more information, see Attach a custom policy to a RAM user.

• If the object to which you want to append content does not exist, the AppendObject operation creates an appendable object.

• If the object to which you want to append content exists:

  • If the object is an appendable object and the specified position from which the append operation starts is equal to the current object size, the data is appended to the end of the object.

  • If the object is an appendable object and the specified position from which the append operation starts is not equal to the current object size, the PositionNotEqualToLength error is returned.

  • If the object is not an appendable object, the ObjectNotAppendable error is returned.

Examples

The following sample code provides an example on how to perform an append upload operation:

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

# Obtain access credentials from environment variables. Before you run the code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())

# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"

# Specify the ID of the region that maps to the endpoint. Example: cn-hangzhou. This parameter is required if you use the signature algorithm V4.
region = "cn-hangzhou"

# Specify the name of your bucket.
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)

# The following code provides an example on how to specify headers for the append upload: 
# headers = dict()
# Specify the caching behavior of the web page for the object. 
# headers['Cache-Control'] = 'no-cache'
# Specify the name of the object when the object is downloaded. 
# headers['Content-Disposition'] = 'oss_MultipartUpload.txt'
# Specify the encoding format for the content of the object. 
# headers['Content-Encoding'] = 'utf-8'
# Specify the request header that is used to check whether the content of the received message is the same as the content of the sent message. 
# headers['Content-MD5'] = 'ohhnqLBJFiKkPSBO1eNaUA=='
# Specify the expiration time. 
# headers['Expires'] = 'Wed, 08 Jul 2022 16:57:01 GMT'
# Specify the access control list (ACL) of the object. In this example, the ACL is set to OBJECT_ACL_PRIVATE. 
# headers['x-oss-object-acl'] = oss2.OBJECT_ACL_PRIVATE
# Specify whether to overwrite the object with the same name in the append upload. 
# headers['x-oss-forbid-overwrite'] = 'true'
# Specify the server-side encryption method. In this example, SSE-OSS is specified for server-side encryption. 
# headers[OSS_SERVER_SIDE_ENCRYPTION] = SERVER_SIDE_ENCRYPTION_AES256
# Specify the storage class of the object. 
# headers['x-oss-storage-class'] = oss2.BUCKET_STORAGE_CLASS_STANDARD
# You can add parameters whose names are prefixed with x-oss-meta- when you call the AppendObject operation to create an appendable object. These parameters cannot be included in the requests when you append content to an existing appendable object. Parameters whose names are prefixed with x-oss-meta- are considered the metadata of the object. 
# headers['x-oss-meta-author'] = 'Alice'
# result = bucket.append_object(exampledir/exampleobject.txt, 0, 'content of first append', headers=headers)

# Set the position from which the first append operation starts to 0. 
# Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. 
result = bucket.append_object('exampledir/exampleobject.txt', 0, 'content of first append')
# If you have appended content to the object, you can obtain the position from which the current append operation starts from the next_position field in the response returned by the last operation or by using bucket.head_object. 
bucket.append_object('<yourObjectName>', result.next_position, 'content of second append')        

References

• For the complete sample code for append upload, visit GitHub.

• For more information about the API operation that you can call to perform append upload, see AppendObject.