This gist illustrates the use of Knex and Bookshelf in a NodeJS application. This script defines an KNEX object which connects to a running instance of PostgreSQL;

db.js

var pg = require('pg');
//Optionally, you may have config file that has the parameters used to connect to PG
//var config = require('../utilities/config');

var knex = require('knex')({
  client: 'pg',
  connection: {
    host     : '127.0.0.1',
    port     : '5432',
    user     : 'some-role-name',
    password : 'role-password',
    database : 'your-database',
    charset  : 'UTF8'
  }
});

var bookshelf = require('bookshelf')(knex);

//we export this here because we will use/require db.js in other scripts
exports.bookshelf = bookshelf;
//Optional - but you may also want to use raw knex and so exporting it here is a good idea
exports.knex = knex;

models.js

//we include the db.js script (in the same director)
var DatabaseUtils = require('./db.js');
//here we get access to the Bookshelf object
var bookshelf = DatabaseUtils.bookshelf;
bookshelf.plugin('registry');

//here we define our model - this points to the userRoles table in PostgreSQL
var UserRole = bookshelf.Model.extend({tableName: 'userRoles'});
//this is for a collection of user roles
var UserRoles = bookshelf.Collection.extend({model: UserRole});

//example of a user
var User = bookshelf.Model.extend({
  tableName: 'users',
  roles: function() {
    //a User will have one or more roles referenced by the userId in the userRoles table
    return this.hasMany(UserRole, 'userId');
  }
});

//as an exercise, write the Users model below:

usage_example.js

// I will use models object to get access to the models such as User(s), UserRoles, etc defined in models.js
var Models = require('./models.js');

//here is how I search for all:
exports.getAll = function (callback){
  Users.forge().fetch().then(function (users){
    var allUsers = (users? users.toJSON(): null);
    if(allUsers){
      callback(null, allUsers);
    }
    else{
      callback(new Error("Users Not Found"));
    }
  })
  .catch(function (err){
    console.log("Error Getting Users. Error is ", err);
  });
};

//Get user is his related roles:
function findUser(id, callback){
  User.forge({'id': id}).fetch({withRelated: ['roles']}).then(function (user){
    user = (user? user.toJSON(): null);
    if(user){
      callback(null, user);
    }
    else{
      callback(new Error("User Not Found"));
    }
  }).catch(function (err){
    callback(err);
  });
}

//As an exercise, write a function that retrieves all user-roles
//