maxbrunsfeld / rel

Arel ported to node js — with some changes

Rel

http://github.com/cjwoodward/rel

Description

Rel is a SQL AST manager for Node JS. It is a straight port of https://github.com/rails/arel. Although it does have some changes of note. These are:

1. No reliance on a database connection. This library builds queries only.
2. It obviously can't use all of the ruby-isms like over-riding the array operator so methods are used instead.

It still holds the same goals as Arel which are:

1. Simplifies the generation complex of SQL queries.
2. Adapts to various RDBMS systems

Before you ask, there will also be a port of ActiveRecord coming in the next little bit.

Installation

npm install rel

Introduction

users = new Rel.Table 'users'
users.project(Rel.star()).toSql()

Will produce

SELECT * FROM users

A more complicated example of command queries is:

users.where(users.column('name').eq('amy'))
# => SELECT * FROM users WHERE users.name = 'amy'

In SQL the selection would contain what you are getting from the database, this is called a projection in Rel.

users.project(users.column('id')) # => SELECT users.id FROM users

Joins resemble SQL:

users.join(photos).on(users.column('id').eq(photos.column('user_id')))
# => SELECT * FROM users INNER JOIN photos ON users.id = photos.user_id

Limit and offset and called take and skip:

users.take(5) # => SELECT * FROM users LIMIT 5
users.skip(4) # => SELECT * FROM users OFFSET 4

GROUP BY is called group:

users.group(users.column('name')) # => SELECT * FROM users GROUP BY name

You can chain all operators, for example:

users.where(users.column('name').eq('amy')).project(users.column('id'))
# => SELECT users.id FROM users WHERE users.name = 'amy'

Another example:

users.where(users.column('name').eq('bob')).where(users.column('age').lt(25))

You can also pass in multiple arguments:

users.where(users.column('name').eq('bob'), users.column('age').lt(25))

The OR operator works like this:

users.where(users.column('name').eq('bob').or(users.column('age').lt(25)))

This is the same as the AS operator.