Lian

Simple object persistence for node.js with MongoDB.

tl;dr

I wanted something more involved than just a DB driver but I didn't want to define a schema or similar meta object.

I also only want to work with the objects I define - if I've saved a Person object, when I invoke a find operation it should return an array of Person objects.

Finally, writing tests for projects that use MongoDB should be easy and not rely on a connection to a DB instance.

See the other goals.

Examples

var lian = require('lian')('localhost/mydb');

function Person (name) {
    lian(this, 'person');
    this.name = name;
}

Person.prototype.getGender = function () {
    return this.gender;
}

var john = new Person('John Smith');
john.gender = "male";

john.save();

Create a projection of Person to find the instance saved above.

var john = new Person('John Smith');
john.find().then(function (results) {

    john = results[0];
    john.name; // "John Smith"
    john.getGender(); // "male"
});

Make some changes to persist.

john.name = "John Anthony Smith";
john.save();

Decoupled, lian's Store object can be used directly.

var lian  = require('lian'),
    Store = lian.Store;

function Person (name) {
    lian(this, 'person');
    this.name = name;
}

var steve = new Person('steve');

typeof steve.insert // "undefined"

var store = new Store('localhost/mydb');
store.insert(steve);

Easy to mock with, for testing. Require the lian/lib/mock module path instead of lian.

var lian = require('lian/lib/mock')('localhost/mydb');

function Person (name) {
    lian(this, 'person');
    this.name = name;
}

var john = new Person('John Smith');
john.gender = "male";

// saved in memory
john.save().then(function () {

    var john2 = new Person('John Smith');
    john2.findOne().then(function (result) {
        result.gender; // "male"
    });
});

Hooks for validation.

var lian = require('lian')('localhost/mydb');

function Person (name) {
    lian(this, 'person', {
        before: {
            'insert': function (person) {
                // check the person has a gender set
                return (person.gender);
            }
        }
    });

    this.name = name;
}

var john = new Person('John Smith');

john.insert().then(
    function () {
        // promise is rejected, see next callback
    },
    function () {
        throw new Error("failed to pass validation");
    }
);

Learn more about validation or read more documentation.

Goals

• Avoid writing result to object mapping code over and over.
• Instance based connections, multiple connections within the same process.
• All asynchronous operations should return a promise.
• Store provides an in-memory alternative, for testing.

Install

Install with npm.

npm install lian

Development

Lian uses monk to talk to MongoDB and promised-io for futures.

Clone the repo...

git clone git://github.com/richardhodgson/lian.git

Use npm to install dependencies.

cd lian && \
npm install --dev

Run the tests.

make test

The tests mock out monk, there are integration tests expecting a MongoDB instance running on localhost:27017. They will create a lian-integration database.

make integration-test