Retrieve the revision

[lpatiny]

It should be possible to make this kind of query:

let url='https://mydb.cheminfo.org/db/eln/entry/b8d44e7857fac800ae119b7671a9c9f3';

let result=await fetch(url, {
	method: 'HEAD',
    mode: 'cors',
    credentials: 'include',
});
console.log(result.headers);

When in all the cases the result.headers is empty while in the network console the ETag containing the revision is correctly return.

It could be related to CORS and I also tried to add on the server the following line:

Header set Access-Control-Allow-Headers "ETag, Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With"

In all my trials the result.headersis an empty object.

Any idea what I'm doing wrong ?

The goal here is to implement a monitoring system to warn the end-users when there is a new revision on the server.

[targos]

This query is not possible in roc and wouldn't be much more efficient than a normal GET because we need to do a full query for permissions

[lpatiny]

In the API documentation there is:

HEAD | /db/:dbname/entry/:uuid | Get HTTP headers about the document | Similar to HEAD /:dbname/:docid in CouchDB

And if I check the network connection in the browser I really retrieve my ETag (revision of couchdb). It is just that from javascript I never could retrieve the header field.

Do you think there should be an new url like:

/db/:dbname/entry/:uuid/_rev

to retrieve revision ?

[targos]

Please read the documentation of fetch. The headers object is not what you think. I confirm result.headers.get('etag') returns the expected value

[lpatiny]

Actually it was not working with cors but I finally found the solution. You need to add in the header an 'Access-Control-Allow-Headers' entry.

Header set Access-Control-Allow-Headers "ETag"

I changed this on our server and it works correctly now.