David's Tech Blog

In my last post I talked about enabling mongodb’s beta text search, which at least to me was a little less than intuitive to accomplish. That’s probably partly because of the beta nature of this feature.

The next challenge was figuring out how to interact with the text search functionality from node.js, since interacting with it from an application that needs to provide search is the whole point. I’m sure that at some point the node.js native driver will support syntax specifically for searching, but at the moment its not there yet. This post assumes that text searches are enabled and you’ve added an index.

Before I show how I am accessing the text search feature, it is helpful to know how my modules are put together in general. At the top of each module I set up the mongo connections. In this post I’m going to use “articles” as my example collection. The setup for the db object looks something like this:

var db = {};
var mongo = require('mongodb').MongoClient;
mongo.connect(config.mongodb.articles.url, function(err, cdb){
db.articles = cdb.collection('articles');
});


This leaves me with a db.articles object that provides access to the collection’s methods, including find, update, save, and so on. I would add each collection needed for the module to the db object in the same way. Unfortunately, the collections object doesn’t have a method for text searches. For that, I need access to the cdb object included in the callback to mongo.connect. To do that, I add the cdb object to my db object, which puts it in scope for the rest of my module.


var db = {};
var mongo = require('mongodb').MongoClient;
mongo.connect(config.mongodb.articles.url, function(err, cdb){
db.articles = cdb.collection('articles');
db.cdb = cdb;
});


Obviously if you have a collection called cdb you’ll need to change this. You could just set the cdb object itself in the module scope.

Then I add a search method to my module. Simplified, this looks like this:

search: function(query, callback){
db.cdb.command({text: "articles", search: query}, function(error,results){
results = (results && results.results) ? results.results : [];
callback(error,results);
});
}

We want the results that this method returns to be an array, not the object with the extra stuff mongodb adds to it. The extra conditional in there is to prevent it from throwing errors if results is undefined or something. There is probably extra logic, acl’s filtering and so on in the real thing, this is stripped down to just show the text search.

The results passed to the callback in this method will be an array of objects, each of which have two elements: score and obj. obj will have the full document for each match.

The extra steps shown here will go away when they add text searches to the driver, but for now this is a fairly functional approach. I hope it saves someone the extra time it took me to sort this out.