Querying a CouchDB view using PouchDB: A map/reduce “GROUP BY” example

If you are like me and do not read the docs before installing and running stuff, an example may help you.

CouchDB (and PouchDB) is (are) awesome. Querying will be awesome as well, unless… it is the first time you deal with those map()/reduce() stuff. I’m not gonna help you there, though, as there are plenty of docs around doing the job of explaining how to use them.

What I am gonna do is give you a quick and dry example of how you could write a query that brings results similar to what an SQL GROUP BY would bring. There you go:

Check an online demo of the code above.

Where’s the secret? When grouping stuff, well, use the group option. It was right there in front of you the whole time, eh? Why didn’t you read the docs… Make sure you use the group_level as well - it is specally useful if you emit array-keys, as in emit([doc.genre, doc.year], 1).

They (group and group_level) have some useful defaults. To get to know them better, now that you were introduced to them, read the docs! - and don’t hesitate to use the demo above to fiddle!