Couchdb retrieve chat history between two users

I'm currently using Couchdb to save chat history between two users. My db contains every inserted messages entered by every user. They are entered like this:

{
  _id: (timestamp),
  from: sender,
  to: receiver,
  message: msg
}

I have a view coded like this:

   function(doc) {
     if (doc.from && doc.to){
         (doc._id, doc);
     }
   }

I'm having a hard time thinking of an idea to retrieve a chat conversion between two users based on my current setup.

I did it the following way inside the view function:

res.forEach(function (row) {
    if(row.from != null || row.to != null){
          if((row.from == socket.username && row.to == receiver) || (row.from == receiver && row.to == socket.username)){
             MsgHistoryContent += row.message + '\n';
          }
    }
});

yet that didn't retrieved all conversation between just two users as it retrieves all the messages from every user.

Anybody can give me a lead? Any help would be appreciated.

P.S: i'm using node.js and cradle.

You can create a map function like this:

function(doc) {
    var key = [doc.from, doc.to].sort(function (a, b) {
        return a.localeCompare(b);
    });

    emit(key.concat(doc._id), doc);
}

Then you will be able to get the conversation between users by querying '?startkey=["user1", "user2"]&endkey=["user1", "user2", {}]'. Of course both start- and endkeys 0 and 1 indexes should be alphabet-sorted.