tverilytt
commented
8 years ago Maybe the CouchDB / Cloudant Design filter function for change feed can be utilized to specify desired filter function. Filter function can also take query parameter(s), which makes it easier to do more dynamic filtering "on demand"...
Filter functions
https://docs.cloudant.com/design_documents.html#filter-functions
Query parameters: https://docs.cloudant.com/cloudant_query.html#query-parameters
Filter function with query parameter:
GET /$DATABASE/_changes?filter=$DESIGN_ID/$FILTER_FUNCTION&status=new
Filter function described in CouchDB The Definitive Guide
http://guide.couchdb.org/draft/notifications.html
CouchDB on filter functions with query parameter sample:
http://couchdb.readthedocs.io/en/latest/couchapp/ddocs.html#filterfun
So e.g. when creating OpenWhisk trigger, a "filter" parameter could specify the filter function:
wsk -v trigger create myTrigger --feed /org_space/cloudantPackage/changes --param dbname mydb --param includeDoc true --params filter mailbox/by_status&status=new
markusthoemmes
rabbah
johnsolm
Hi! In some scenarios it would have been handy and practical to be able to specify a filter for a Trigger. The filter could have been passed on to the Feed creating the Trigger. And then the trigger fires only if the filter condition(s) is satisfied.
In a scenario I am having now, I do many concurrent (bulk) upcerts to a Cloudant ddatabase. My OpenWhisk changes feed fires the Trigger for every single upcert. The Trigger calls an Action for every upcert, and in the Action, I do the filtering on certain value(s) of the received document / payload.
Being able to specify the filtering on the Trigger itself, would make the Action simpler, and also one could create many Triggers (with different filters), all calling the same Action. In my scenario, I have to create a new Action (and Rule associating the Action with the Trigger) for every different filter I want to have.
With best regards -jo2