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Date: Wed, 29 Apr 2009 19:43:09 +0200
Message-ID: <2c8465c20904291043r3f1f9402je8614e6db263ff04@mail.gmail.com>
Subject: Re: Howto drop rows with reduce?
From: Luke Randall <luke.randall@gmail.com>
To: user@couchdb.apache.org
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Jurg van Vliet wrote:
> if i don't emit anything in the last emit statement i get comments for all of my document types. then case i end up with a list of articles and comments, both with a comment count.
>

Hi Jurg

>From what I understand of your situation, I don't see why what Paul
suggested wouldn't work. If you have the following as your map
function

function(doc) {
    if( doc.type == 'Article') {
        emit( doc._id, 0);
    } else if( doc.type == 'Comment') {
        emit( doc.path[0], 1);
    }
}


when you reduce it* you will have a list of articles with a comment
count. Note that you there is no requirement to call emit for each
document. If you don't want a document to appear in a view then just
don't call emit on it. Reduce isn't meant to be used as a filter,
that's what map is for.

* Remember to add :group => true to your couchrest view call, as Futon
silently adds it, but it otherwise defaults to being false.

Sorry, this is basically a rehash of what Paul said, but it seems that
you possibly misunderstood his suggestion. Either that or I
misunderstood your reply, which is also quite possible... :)

- Luke

PS Sorry if this message breaks threading; I wasn't subscribed to the
list, so I had to copy and paste this.