Open S3 object as a string with Boto3

问题:

I'm aware that with Boto 2 it's possible to open an S3 object as a string with:

get_contents_as_string() http://boto.readthedocs.org/en/latest/ref/file.html?highlight=contents%20string#boto.file.key.Key.get_contents_as_string

Is there an equivalent function in boto3 ?

回答1:

read will return bytes. At least for Python 3, if you want to return a string, you have to decode using the right encoding:

import boto3

s3 = boto3.resource('s3')

obj = s3.Object(bucket, key)
obj.get()['Body'].read().decode('utf-8') 

回答2:

This isn't in the boto3 documentation. This worked for me:

object.get()["Body"].read()

object being an s3 object: http://boto3.readthedocs.org/en/latest/reference/services/s3.html#object

回答3:

I had a problem to read/parse the object from S3 because of .get() using Python 2.7 inside an AWS Lambda.

I added json to the example to show it became parsable :)

import boto3
import json

s3 = boto3.client('s3')

obj = s3.get_object(Bucket=bucket, Key=key)
j = json.loads(obj['Body'].read())

NOTE (for python 2.7): My object is all ascii, so I don't need .decode('utf-8')

NOTE (for python 3.6+): We moved to python 3.6 and discovered that read() now returns bytes so if you want to get a string out of it, you must use:

j = json.loads(obj['Body'].read().decode('utf-8'))

回答4:

If body contains a io.StringIO, you have to do like below:

object.get()['Body'].getvalue()