using ensureIndex in mongodb schema using mongoose

Question

I would like to call ensureIndex on the authorName, what is the command and where in this code should I put it?

var mongoose = require('mongoose');

// defines the database schema for this object
var schema = mongoose.Schema({
    projectName : String,
    authorName : String,
    comment : [{
        id : String,                                    
        authorName : String,
        authorEmailAddress : { type : String, index : true }    
    }]
});

// Sets the schema for model
var ProjectModel = mongoose.model('Project', schema);

// Create a project
exports.create = function (projectJSON) {
    var project = new ProjectModel({
        projectName : projectJSON.projectName,
        authorName : projectJSON.authorName,    

        comment : [{
            id : projectJSON.comments.id,                                           
            authorName : projectJSON.comments.authorName,                           
            authorEmailAddress : projectJSON.authorEmailAddress
        });

        project.save(function(err) {
            if (err) {
                console.log(err);
            } else{
                console.log("success");
            }
        });
    });
}

Answer 1

You don't call ensureIndex directly, you indicate that field should be indexed in your schema like this:

var schema = mongoose.Schema({
  projectName : String,
  authorName : { type: String, index: true }
});

Based on that definition, Mongoose will call ensureIndex for you when you register the model via the mongoose.model call.

To see the ensureIndex calls that Mongoose is making, enable debug output by adding the following to your code:

mongoose.set('debug', true);

Answer 2

You could use this statement:

mongoose.connection.collections['my_collection'].ensureIndex({ "key": 1 }, { "unique": true }, callback);

For example you want to do some integration tests, so you will need to drop your collections rapidly. In that case mongoose doesn't setup indexes again during runtime even if option autoIndex is set to true. This answer could be useful in that case.