Hi Simon, Thanks for the quick reply. This might serve my use case. I'll try this out and post back if required.
Thanks, Chirayu. On Wed, Oct 20, 2010 at 6:28 PM, Simon Metson <[email protected]>wrote: > Hi, > http://guide.couchdb.org/draft/notifications.html#filters > > I think you'd want to query _changes with a filter to check that the > doc.name is the same as that from the query string, slightly modifying the > example from the book: > > function(doc, req) > { > if(doc.id == req.query.id && doc.name != req.query.name) { > return true; > } > > return false; > } > > You'd then query http://localhost:5984/helloworld/_changes with something > like _changes?filter=myapp/myfilter&id=app1&name=Hello which would return > all changes for documents with id=app1 where the name differs from what you > set. > > I don't think you can filter what the change is reliably, though. For > instance the filter above would miss someone changing the name back to > "Hello" unless you change the query string, which means your application > will need to hold that piece of state information. You can easily see all > changes for a given document, and then further filter later on, though, > maybe that's sufficient? > Cheers > Simon > > > On 20 Oct 2010, at 13:31, chirayu shah wrote: > > Hi, >> >> The output that we get with the _changes database API tells us which >> document was changed and its revision information. >> Is there a way to get the notification when a particular key of a document >> is changed? >> >> Basically is there a way to listen to a specific key of a document of a >> database? >> >> For eg: Suppose I have a database as "helloworld", which has 2 documents >> "app1" and "app2" whose contents are as follows: >> >> app1 : >> >> { >> "_id": "app1", >> "_rev": "2-c1765690ce0ba5c4d51bd6e06f6d63e1", >> "name": "Hello", >> "title": "World" >> } >> >> >> app2: >> >> { >> "_id": "1", >> "_rev": "2-95ca949e944d55bdb0dc79b8d8223f05", >> "a": 2, >> "b": 4 >> } >> >> >> Now I want to listen to the key "name" of the document "app1" for changes. >> So I should receive the notification when the value of "name" changes and >> not if the value of "title" changes. >> >> Is there a way to do this in CouchDB? If yes, then how? >> Any help would be much appreciated. >> >> Thanks, >> Chirayu. >> > >
