CODEWITHSUNDEEP
couchdb
blueFast
blueFast

Reputation: 44371

Are CouchDB filters limited to the _changes feed?

As specified here, a filter can be used with the _changes feed like this:

curl "$HOST/db/_changes?filter=app/important"

Now I am trying to use this pattern with a standard view access, like this:

curl -X GET $HOST/db/_design/live_data/_view/all-comments&filter=live_data/bytag?tag=testing

I have also tried ? instead of &:

curl -X GET $HOST/db/_design/live_data/_view/all-comments?filter=live_data/bytag?tag=testing

But the filter has no effect: all documents are shown, even those which should not be validated by the filter.

The filter that I am using is:

function(doc, req)
{
  for( var i in doc.tags ) {
    if(doc.tags[i] == req.query.tag) {
      return true;
    }
  }
  return false;
}

Upvotes: 2

Views: 658

Answers (2)

fiatjaf
fiatjaf

Reputation: 12159

If this worked it would impose on CouchDB the responsibility of iterating through all the view's records and execute the filter function on them. It is not a good way of doing things, especially when you have the possibility of pre-indexing documents using views and arrays of keys (like [date, tag]).

But nothing will forbid you of implementing this filter in a backend of your own. You would only have to load all the view documents from CouchDB, execute the filter function on them and return. But that wouldn't be fast.

Upvotes: 1

Antonis Anastasiadis
Antonis Anastasiadis

Reputation: 269

Yes, it seems that filters are limited to _changes requests only. If you want to filter data from views, you can use "startkey" and "endkey" parameters with possibly more complex json keys and/or reduce grouping levels to achieve your desired results.

Upvotes: 1

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