同じ名前のオブジェクトの上書きを防止する - Object Storage Service

既定では、既存のオブジェクトと同じ名前のオブジェクトをアップロードすると、既存のオブジェクトはアップロードされたオブジェクトによって上書きされます。このトピックでは、x-oss-forbid-overwriteリクエストヘッダーを設定して、オブジェクトをコピーするとき、または単純なアップロードまたはマルチパートアップロードを実行するときに、既存のオブジェクトが同じ名前のオブジェクトによって上書きされないようにする方法について説明します。

使用上の注意

このトピックでは、中国 (杭州) リージョンのパブリックエンドポイントを使用します。 OSSと同じリージョンにある他のAlibaba CloudサービスからOSSにアクセスする場合は、内部エンドポイントを使用します。 OSSリージョンとエンドポイントの詳細については、「リージョン、エンドポイント、オープンポート」をご参照ください。
このトピックでは、アクセス資格情報は環境変数から取得します。アクセス資格情報の設定方法の詳細については、「アクセス資格情報の設定」をご参照ください。
このトピックでは、OSSエンドポイントを使用してOSSClientインスタンスを作成します。カスタムドメイン名またはSTS (Security Token Service) を使用してOSSClientインスタンスを作成する場合は、「初期化」をご参照ください。

単純なアップロードタスクでの上書きの防止

次のサンプルコードは、単純なアップロードを実行するときに、既存のオブジェクトが同じ名前のオブジェクトによって上書きされないようにする方法の例を示しています。

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Obtain access credentials from environment variables. Before you run the sample 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)

# Upload the object. 
# Specify whether the object that is uploaded by calling the PutObject operation overwrites the existing object that has the same name. 
# By default, if x-oss-forbid-overwrite is not specified, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to false, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to true, the object that is uploaded cannot overwrite the existing object that has the same name. If an object that has the same name exists in the bucket, OSS returns an error. 
headers = {'x-oss-forbid-overwrite': 'true'}
result = bucket.put_object('yourObjectName', 'content of object', headers=headers)

# Display the returned HTTP status code. 
print('http status: {0}'.format(result.status))
# Display the request ID. A request ID uniquely identifies a request. We recommend that you add this parameter to the logs. 
print('request_id: {0}'.format(result.request_id))
# Display the ETag value returned by the put_object method. 
print('ETag: {0}'.format(result.etag))
# Display the HTTP response headers. 
print('date: {0}'.format(result.headers['date']))

オブジェクトコピータスクでの上書きの防止

小さなオブジェクトをコピーする

次のサンプルコードでは、同じ名前の既存のオブジェクトを上書きせずに小さなオブジェクトをコピーする方法の例を示します。

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
auth = oss2.ProviderAuth(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. 
# Specify the name of your bucket.
bucket = oss2.Bucket(auth, 'https://oss-cn-hangzhou.aliyuncs.com', 'yourBucketName')

# Specify whether the object that is copied by calling the copy_object operation overwrites the existing object that has the same name. 
# By default, if x-oss-forbid-overwrite is not specified, an existing object is overwritten by a copied object with the same name. 
# If x-oss-forbid-overwrite is set to false, an existing object is overwritten by a copied object with the same name. 
# If x-oss-forbid-overwrite is set to true, an existing object is not overwritten by a copied object with the same name. If the existing object has the same name as the copied object, an error is reported. 
headers = dict()
headers = {'x-oss-forbid-overwrite':'true'}
bucket.copy_object('yourSourceBucketName', 'yourSourceObjectName', 'yourDestinationObjectName', headers=headers)

大きなオブジェクトをコピーする

次のサンプルコードは、マルチパートコピーを使用してラージオブジェクトをコピーするときに、既存のオブジェクトが同じ名前のラージオブジェクトによって上書きされないようにする方法の例を示しています。

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
from oss2.models import PartInfo
from oss2 import determine_part_size
# Obtain access credentials from environment variables. Before you run the sample 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)

src_object = 'yourSourceObjectName'
dst_object = 'yourDestinationObjectName'

total_size = bucket.head_object(src_object).content_length
part_size = determine_part_size(total_size, preferred_size=100 * 1024)

# Initiate a multipart upload task. 
# Specify whether to overwrite an object that has the same name when you copy an object. 
# By default, if x-oss-forbid-overwrite is not specified, the object that is copied overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to false, the object that is copied overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to true, an existing object is not overwritten by a copied object with the same name. If the existing object has the same name as the copied object, an error is reported. 
headers = dict()
headers = {'x-oss-forbid-overwrite': 'true'}
upload_id = bucket.init_multipart_upload(dst_object, headers=headers).upload_id
parts = []

# Copy each part. 
part_number = 1
offset = 0
while offset < total_size:
    num_to_upload = min(part_size, total_size - offset)
    byte_range = (offset, offset + num_to_upload - 1)

    result = bucket.upload_part_copy(bucket.bucket_name, src_object, byte_range,dst_object, upload_id, part_number)
    parts.append(PartInfo(part_number, result.etag))

    offset += num_to_upload
    part_number += 1

# Complete the multipart copy task. 
# Specify whether to overwrite an object that has the same name when you copy an object. 
# By default, if x-oss-forbid-overwrite is not specified, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to false, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to true, an existing object is not overwritten by a copied object with the same name. If the existing object has the same name as the copied object, an error is reported. 
headers = dict()
headers = {'x-oss-forbid-overwrite':'true'}
bucket.complete_multipart_upload(dst_object, upload_id, parts, headers=headers)

マルチパートアップロードタスクでの上書きの防止

次のサンプルコードは、マルチパートアップロードを使用してオブジェクトをアップロードするときに、既存のオブジェクトが同じ名前のオブジェクトによって上書きされないようにする方法の例を示しています。

# -*- coding: utf-8 -*-
import os
from oss2 import SizedFileAdapter, determine_part_size
from oss2.models import PartInfo
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Obtain access credentials from environment variables. Before you run the sample 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)

key = 'yourObjectName'
filename = 'yourLocalFile'

total_size = os.path.getsize(filename)
# Specify the determine_part_size method to determine the part size. 
part_size = determine_part_size(total_size, preferred_size=100 * 1024)

# Initiate a multipart upload task. 
# Specify whether to overwrite the existing object that has the same name when you perform multipart upload. 
# By default, if x-oss-forbid-overwrite is not specified, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to false, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to true, the object that is uploaded cannot overwrite the existing object that has the same name. If an object that has the same name exists in the bucket, OSS returns an error. 
headers = {'x-oss-forbid-overwrite': 'true'}
upload_id = bucket.init_multipart_upload(key, headers=headers).upload_id
parts = []

# Upload the parts. 
with open(filename, 'rb') as fileobj:
    part_number = 1
    offset = 0
    while offset < total_size:
        num_to_upload = min(part_size, total_size - offset)
        # The SizedFileAdapter(fileobj, size) method generates a new object and recalculates the position from which the append operation starts. 
        result = bucket.upload_part(key, upload_id, part_number,
                                    SizedFileAdapter(fileobj, num_to_upload))
        parts.append(PartInfo(part_number, result.etag))

        offset += num_to_upload
        part_number += 1

# Complete the multipart upload task. 
# Specify whether to overwrite the existing object that has the same name when you perform multipart upload. 
# By default, if x-oss-forbid-overwrite is not specified, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to false, the object that is uploaded overwrites the existing object that has the same name. 
# If x-oss-forbid-overwrite is set to true, the object that is uploaded cannot overwrite the existing object that has the same name. If an object that has the same name exists in the bucket, OSS returns an error. 
headers = {'x-oss-forbid-overwrite': 'true'}
bucket.complete_multipart_upload(key, upload_id, parts, headers=headers)

# Verify the result of the multipart upload task. 
with open(filename, 'rb') as fileobj:
    assert bucket.get_object(key).read() == fileobj.read()

Object Storage Service:同じ名前のオブジェクトの上書きを防止する

使用上の注意

単純なアップロードタスクでの上書きの防止

オブジェクトコピータスクでの上書きの防止

マルチパートアップロードタスクでの上書きの防止

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