Boto: S3: set_metadata does not set metadata remotely in the simplest case.

[acrefoot]

S3: set_metadata doesn't actually update metadata unless you call one of the set_contents_from_* command.

It will keep it in the key that you have in memory, but if you restart python and get that key again, it won't have that metadata.

[garnaat]

Metadata can only be set at the time the object is written to S3 or when it is copied. There really isn't anything boto can do about this.

[mfschwartz]

Hi Mitch,

I don't think that's correct. You can do copy-in-the-cloud from an object to itself, specifying x-amz-copy-source to point to the origin object and x-amz-metadata-directive:REPLACE, and then setting headers (which has the effect of just updating the metadata/headers). For example, running the following command:

gsutil -d setmeta -h Content-Type:text/html s3://mfsbucket/abc

here's the HTTP that's sent:

send: 'PUT /mfsbucket/abc HTTP/1.1\r\nHost: s3.amazonaws.com\r\nAccept-Encoding: identity\r\nContent-Length: 0\r\nx-amz-storage-class: STANDARD\r\nUser-Agent: Boto/2.6.0-dev (darwin) gsutil/3.19_PRE (darwin)\r\nx-amz-copy-source: mfsbucket/abc\r\nDate: Wed, 14 Nov 2012 22:05:27 GMT\r\ncontent-type: text/html\r\nAuthorization: ....=\r\nx-amz-metadata-directive: REPLACE\r\n\r\n'

And after running the command, I verified that the Content-Type was indeed updated.

(I implemented this command for Google Cloud Storage, but it works for S3 as well.)

Mike

[garnaat]

I agree that you can do that but I don't think you should do that every time someone changes a value in the local object, do you?

[mfschwartz]

Oh, sorry, I didn't realize the context here - acrefoot@ was asking about
setting metadata in the in-memory object, and expecting that it would sync
through to the storage service. I agree, you don't want to do that every
time someone changes a value in the local object.

Mike

On Wed, Nov 14, 2012 at 3:17 PM, Mitch Garnaat [email protected]:

I agree that you can do that but I don't think you should do that every
time someone changes a value in the local object, do you?

—
Reply to this email directly or view it on GitHubhttps://github.com/boto/boto/issues/1007#issuecomment-10388313.

[xiongchiamiov]

I agree that you can do that but I don't think you should do that every time someone changes a value in the local object, do you?

It would be nice, however, to have a save() method that does this on-demand, as with most ORMs. Right now, the lack of something like this or a disclaimer in the docs makes it _seem_ like calling set_metadata() will, well, set the metadata on s3. This is particularly non-obvious because of the perceived symmetry between the various set_* methods.

I guess some additional documentation would be an easier solution, although save() would be rather convenient as a user. :)

[alexmadjar]

+1 to @xiongchiamiov