Question

我想链接下载S3存储的文件。

<a href="https://s3.region.amazonaws.com/bucket/file.txt" download>DownLoad</a> 它仅在浏览器上显示file.txt。所以我找到了下载方式。它是将Content-Disposition : attachment元标记添加到文件。

但是我需要将此meta标签自动添加到新文件中。所以我用python制作了lambda function。

import json
import urllib.parse
import boto3

print('Loading function')

s3 = boto3.client('s3')


def lambda_handler(event, context):
    #print("Received event: " + json.dumps(event, indent=2))

    # Get the object from the event and show its content type
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.parse.unquote_plus(event['Records'][0]['s3']['object']['key'], encoding='utf-8')
    try:
        response = s3.get_object(Bucket=bucket, Key=key)
        print("CONTENT TYPE: " + response['ContentType'])

    except Exception as e:
        print(e)
        print('Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as this function.'.format(key, bucket))
        raise e

    try:
        s3_2 = boto3.resource('s3')
        s3_object = s3_2.Object(bucket, key)
        print(s3_object.metadata)
        s3_object.metadata.update({'ContentDisposition':'attachment'})

        print(bucket, key)

        s3_object.copy_from(CopySource={'Bucket':bucket, 'Key':key}, Metadata=s3_object.metadata, MetadataDirective='REPLACE')

    except:
        print(s3_object.metadata)

    return response['ContentType']

但是此函数添加user defined metatag而不是system metatag。。。

我该怎么办？

Answer 1

Content-Disposition被S3视为（某种程度上）类似于系统元数据，而不是自定义/用户定义的元数据，因此它具有自己的参数。

s3_object.copy_from(CopySource={'Bucket':bucket, 'Key':key}, ContentDisposition='attachment',  Metadata=s3_object.metadata, MetadataDirective='REPLACE')

请注意，您仍然需要如图所示的Metadata和MetadataDirective才能起作用，但是由于您没有更改自定义元数据，因此不需要s3_object.metadata.update()。

如何链接到S3文件下载

1 个答案: