问题描述
必须有一种简单的方法来获取文件大小(密钥大小)而无需拉取整个文件.我可以在 AWS S3 浏览器的属性中看到它.我想我可以从HEAD"请求的Content-length"标头中得到它.但我并没有把如何用 boto 做到这一点的要点联系起来.如果您发布了一些比标准 boto 文档 中更全面的示例的链接，请多加夸奖.
There must be an easy way to get the file size (key size) without pulling over a whole file. I can see it in the Properties of the AWS S3 browser. And I think I can get it off the "Content-length" header of a "HEAD" request. But I'm not connecting the dots about how to do this with boto. Extra kudos if you post a link to some more comprehensive examples than are in the standard boto docs.
因此以下内容似乎可以解决问题(尽管从查看源代码时我并不完全确定.):
So the following seems to do the trick (though from looking at source code I'm not completely sure.):
bk = conn.get_bucket('my_bucket_name')
ky = boto.s3.key.Key(bk)
ky.open_read() ## This sends a GET request.
print ky.size
现在，我将把问题留待评论、更好的解决方案或指向示例的指针.
For now I'll leave the question open for comments, better solutions, or pointers to examples.
推荐答案
这行得通:
bk = conn.get_bucket('my_bucket_name')
key = bk.lookup('my_key_name')
print key.size
查找方法只是在存储桶上对键名执行 HEAD 请求，因此它将返回键的所有标头(包括内容长度)，但不会传输键的任何实际内容.
The lookup method simply does a HEAD request on the bucket for the keyname so it will return all of the headers (including content-length) for the key but will not transfer any of the actual content of the key.
S3 教程l 提到了这一点，但不是很明确，也不是在这个确切的上下文中.我会在这方面添加一个部分，以便于查找.
The S3 tutorial mentions this but not very explicitly and not in this exact context. I'll add a section on this to help make it easier to find.
注意:对于像 http://boto.cloudhackers.com/s3_tut.html 这样返回 404 的旧链接，添加 "/en/latest"在 ".com" 之后: http://boto.cloudhackers.com/en/latest/s3_tut.html .(需要有人探索 mod_rewrite...)
Note: for every old link like http://boto.cloudhackers.com/s3_tut.html that returns a 404, add in "/en/latest" right after the ".com" : http://boto.cloudhackers.com/en/latest/s3_tut.html . (Someone needs to explore mod_rewrite...)
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