You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@couchdb.apache.org by Paul Carey <pa...@gmail.com> on 2009/01/08 23:25:38 UTC
HTTP response codes on conflict
I was wondering about the error codes returned by CouchDB in case of
database conflict and document conflict.
An attempt to create an already existing database returns a 409.
$ curl -v -s -X PUT localhost:5984/shiny_new_db 2>&1 | grep '< HTTP'
< HTTP/1.1 201 Created
$ curl -v -s -X PUT localhost:5984/shiny_new_db 2>&1 | grep '< HTTP'
< HTTP/1.1 409 Conflict
>From the 409 section of the HTTP spec [1]
"This code is only allowed in situations where it is expected that the
user might be able to resolve the conflict and resubmit the request."
But the database already exists - there is no resolution, so I'm not
sure a 409 is the best response code here.
The 412 section of the spec states
"The precondition given in one or more of the request-header fields
evaluated to false"
Arguably, this is what should be returned when an attempt is made to
re-create a pre-existing database - the precondition is that you can
PUT to a database URI at most once.
As for document conflict, CouchDB returns a 412.
$ curl -v -s -X PUT -d '{"_id":"foo"}' localhost:5984/shiny_new_db/foo
2>&1 | grep '< HTTP'
< HTTP/1.1 201 Created
$ curl -v -s -X PUT -d '{"_id":"foo"}' localhost:5984/shiny_new_db/foo
2>&1 | grep '< HTTP'
< HTTP/1.1 412 Precondition Failed
I think a document conflict might have returned a 409 at some point in
the past. In fact this is what the Document API wiki page [2] states
it returns. Given that the user may resolve the conflict and resubmit
the request, a 409 makes sense here.
To clarify, unless I'm missing something, I think an attempt to create
an already existing database should return a 412 and an attempt to
update a document that results in a conflict should return a 409.
All the best
Paul
[1] http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
[2] http://wiki.apache.org/couchdb/HTTP_Document_API