orm

Object Relational Mapping

Install

npm install orm@2.0.0-alpha6

Despite the alpha tag, this is the recommended version for new applications.

DBMS Support

• MySQL
• PostgreSQL
• SQLite

Introduction

This is a node.js object relational mapping module.

Here is an example on how to use it:

var orm = require('orm');

orm.connect("mysql://username:password@host/database", function (err, db) {
	if (err) throw err;

	var Person = db.define('person', {
		name      : String,
		surname   : String,
		age       : Number,
		male      : Boolean,
		continent : [ 'Europe', 'America', 'Asia', 'Africa', 'Australia', 'Antartica' ], // ENUM type
		photo     : Buffer, // BLOB/BINARY
		data      : Object // JSON encoded
	}, {
		methods: {
			fullName: function () {
				return this.name + ' ' + this.surname;
			}
		},
		validations: {
			age: orm.validators.rangeNumber(18, undefined, 'under-age')
		}
	});

	Person.find({ surname: "Doe" }, function (err, people) {
		// SQL: "SELECT * FROM person WHERE surname = 'Doe'"

		console.log("People found: %d", people.length);
		console.log("First person: %s, age %d", people[0].fullName(), people[0].age);

		people[0].age = 16;
		people[0].save(function (err) {
			// err.msg = 'under-age';
		});
	});
});

Models

A Model is a structure binded to one or more tables, depending on the associations. The model name is assumed to be the table name. After defining a model you can use it to manipulate the table.

After defining a Model you can get a specific element or find one or more based on some conditions.

Finding Items

Model.get(id, [ options ], cb)

To get a specific element from the database use Model.get.

Person.get(123, function (err, person) {
	// finds person with id = 123
});

Model.find([ conditions ] [, options ] [, limit ] [, order ] [, cb ])

Finding one or more elements has more options, each one can be given in no specific parameter order. Only options has to be after conditions (even if it's an empty object).

Person.find({ name: "John", surname: "Doe" }, 3, function (err, people) {
	// finds people with name='John' AND surname='Doe' and returns the first 3
});

If you need to sort the results because you're limiting or just because you want them sorted do:

Person.find({ surname: "Doe" }, "name", function (err, people) {
	// finds people with surname='Doe' and returns sorted by name ascending
});
Person.find({ surname: "Doe" }, [ "name", "Z" ], function (err, people) {
	// finds people with surname='Doe' and returns sorted by name descending
	// ('Z' means DESC; 'A' means ASC - default)
});

There are more options that you can pass to find something. These options are passed in a second object:

Person.find({ surname: "Doe" }, { offset: 2 }, function (err, people) {
	// finds people with surname='Doe', skips the first 2 and returns the others
});

Available options

• offset: discards the first N elements
• limit: although it can be passed as a direct argument, you can use it here if you prefer
• only: if you don't want all properties, you can give an array with the list of properties you want

Chaining

If you prefer another less complicated syntax you can chain .find() by not giving a callback parameter.

Person.find({ surname: "Doe" }).limit(3).offset(2).only("name", "surname").run(function (err, people) {
    // finds people with surname='Doe', skips first 2 and limits to 3 elements,
    // returning only 'name' and 'surname' properties
});

Associations

An association is a relation between one or more tables.

hasOne vs. hasMany Associations

If you have a relation of 1 to 0 or 1 to 1, you should use hasOne association. This assumes a column in the model that has the id of the other end of the relation.

var Person = db.define('person', {
	name : String
});
var Animal = db.define('animal', {
	name : String
});
Animal.hasOne("owner", Person); // assumes column 'owner_id' in 'animal' table

// get animal with id = 123
Animal.get(123, function (err, Foo) {
	// Foo is the animal model instance, if found
	Foo.getOwner(function (err, John) {
		// if Foo animal has really an owner, John points to it
	});
});

For relations of 1 to many you have to use hasMany associations. This assumes another table that has 2 columns, one for each table in the association.

var Person = db.define('person', {
	name : String
});
Person.hasMany("friends"); // omitting the other Model, it will assume self model

Person.get(123, function (err, John) {
	John.getFriends(function (err, friends) {
		// assumes table person_friends with columns person_id and friends_id
	});
});

The hasMany associations can have additional properties that are assumed to be in the association table.

var Person = db.define('person', {
	name : String
});
Person.hasMany("friends", {
    rate : Number
});

Person.get(123, function (err, John) {
	John.getFriends(function (err, friends) {
		// assumes rate is another column on table person_friends
		// you can access it by going to friends[N].extra.rate
	});
});

If you prefer you can activate autoFetch. This way associations are automatically fetched when you get or find instances of a model.

var Person = db.define('person', {
	name : String
});
Person.hasMany("friends", {
    rate : Number
}, {
    autoFetch : true
});

Person.get(123, function (err, John) {
    // no need to do John.getFriends() , John already has John.friends Array
});

You can also define this option globally instead of a per association basis.

var Person = db.define('person', {
	name : String
}, {
    autoFetch : true
});
Person.hasMany("friends", {
    rate : Number
});