Object Storage Service:Manage object metadata

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS by using other Alibaba Cloud services in the same region as OSS, use an internal endpoint For more information about the regions and endpoints supported by OSS, see Regions and endpoints.
• 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 STS, see Initialization.
• To configure object metadata, you must have the oss:PutObject permission. To query object metadata, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

Configure HTTP headers

The following code provides an example on how to configure HTTP headers for the exampleobject.txt object in the exampledir directory of the examplebucket bucket.

# -*- coding: utf-8 -*-
import oss2
# The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in OSS is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
auth = oss2.Auth('yourAccessKeyId', 'yourAccessKeySecret')
# 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 the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'yourEndpoint', 'examplebucket')
# Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
object_name = 'exampledir/exampleobject.txt'
# Specify the string that you want to upload. 
content = '{"age": 1}'
# Configure HTTP headers. For example, set the Content-Type header to 'application/json; charset=utf-8'. 
bucket.put_object(object_name, content, headers={'Content-Type': 'application/json; charset=utf-8'})

Configure user metadata

You can configure user metadata of an object to describe the object.

The following code provides an example on how to configure the user metadata of the exampleobject.txt object in the exampledir directory of the examplebucket bucket:

# -*- coding: utf-8 -*-
import oss2

# The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in OSS is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
auth = oss2.Auth('yourAccessKeyId', 'yourAccessKeySecret')
# 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 the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'yourEndpoint', 'examplebucket')
# Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
object_name = 'exampledir/exampleobject.txt'
# Specify the string that you want to upload. 
content = 'a novel'
# Configure the user metadata that must be prefixed with x-oss-meta-. For example, set the x-oss-meta-author metadata to 'O. Henry'.  
bucket.put_object(object_name, content, headers={'x-oss-meta-author': 'O. Henry', 'Content-Type': 'application/json; charset=utf-8'})

Modify object metadata

The following code provides an example on how to modify the metadata of the exampleobject.txt object in the exampledir directory of the examplebucket bucket:

# -*- coding: utf-8 -*-
import oss2

# The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in OSS is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
auth = oss2.Auth('yourAccessKeyId', 'yourAccessKeySecret')
# 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 the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'yourEndpoint', 'examplebucket')
# Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
object_name = 'exampledir/exampleobject.txt'

bucket.update_object_meta(object_name, {'x-oss-meta-author': 'O. Henry'})
# Each time you call bucket.update_object_meta, the existing user metadata is updated. 
bucket.update_object_meta(object_name, {'x-oss-meta-price': '100 dollar'})

The following code provides an example on how to modify object metadata such as Content-Type:

# -*- coding: utf-8 -*-
import oss2

# The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in OSS is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
auth = oss2.Auth('yourAccessKeyId', 'yourAccessKeySecret')
# 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 the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'yourEndpoint', 'examplebucket')
# Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
object_name = 'exampledir/exampleobject.txt'

bucket.update_object_meta(object_name, {'x-oss-meta-author': 'O. Henry'})
# Each time you call bucket.update_object_meta, the existing user metadata is updated. 
bucket.update_object_meta(object_name, {'Content-Type': 'text/plain'})

Query object metadata

You can use the methods provided by OSS SDK for Python to query object metadata.

The following code provides an example on how to query the metadata of the exampleobject.txt object in the exampledir directory of the examplebucket bucket:

# -*- coding: utf-8 -*-
import oss2

# The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in OSS is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. 
auth = oss2.Auth('yourAccessKeyId', 'yourAccessKeySecret')
# 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 the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'yourEndpoint', 'examplebucket')
# Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. 
object_name = 'exampledir/exampleobject.txt'

# Query part of the object metadata by using the get_object_meta method. 
simplifiedmeta = bucket.get_object_meta(object_name)
print(simplifiedmeta.headers['Last-Modified']) 
print(simplifiedmeta.headers['Content-Length']) 
print(simplifiedmeta.headers['ETag']) 

# Query all object metadata by using the head_object method. 
objectmeta = bucket.head_object(object_name)
# In this example, the returned part of the object metadata is displayed. You can add the code to display all object metadata. 
print(objectmeta.headers['Content-Type']) 
print(objectmeta.headers['Last-Modified']) 
print(objectmeta.headers['x-oss-object-type'])

References

• For the complete sample code that is used to configure and query object metadata, visit GitHub.
• For more information about the API operation that you can call to configure object metadata, see PutObject.
• For more information about the API operation that you can call to query object metadata, see GetObjectMeta.