expose_db

ExposeDB

ExposeDB provides raw, read-only access to your data over an HTTP JSON API. It uses the excellent Sinatra and Sequel libraries for all of the real work.

WARNING: ExposeDB doesn't offer any secure options, and as such is expected to be used only in a high-trust network!

ExposeDB consists of both a client and server in one package. The server need not be used with the client: it simply provides a JSON endpoint. The client will wrap that JSON endpoint in a very simple Sequel-like API.

But Why?

Ideally, connecting straight to the source database would always be possible. Since it's not: why.

Server Usage

ExposeDB is in a very alpha stage of development, but seems to be doing a rudimentary job querying for data. Output options are currently limited to all fields in a table and is only exposed via JSON.

expose-db SEQUEL_DATABASE_URI

For example:

expose-db postgres://user:password@dbhost/my_db

Existing endpoints:

• / - Simple query interface
• /my_table - Get all the records in my_table as JSON
• /my_table?q=ENCODED_QUERY&values[]=2&values[]=bob - replace ?'s in ENCODED_QUERY with [2, 'bob']

Client Usage

ExposeDB client use isn't required to use the server, but provides a very simple mapping layer built with Hashie. Use exposed_as to define the server's table name after inheriting from ExposeDB::Model and setting your subclass's base_uri. You can find and filter your models, along with anything that [HTTParty][httparty] provides.

Since the models are built from a Hashie::Mash, you don't need to define any fields or columns on the client side.

require 'expose_db/model'

class BaseModel < ExposeDB::Model
  base_uri 'http://api.example.com/v1'
end

class Person < BaseModel
  exposed_as 'people'

  # Class is inferred from singular of relation name, and foreign key is assumed
  # to be this_class_name_id. Singular inflections are very limited, so you may
  # need to specify class_name here
  has_many :tasks
end

class Task < BaseModel
  exposed_as 'tasks'

  # Assume the returned task has a person_id column and the class_name is Person
  belongs_to :person

  # Provie a wrapper for the underlying string from the ExposeDB server
  def completed_at
    ca = self[:completed_at]
    ca ? Time.parse(ca) : nil
  end
end

bob = Person.find(123)
#=> your person (by column `id`) or raise ExposeDB::RecordNotFound

bob.tasks
#=> find all tasks with person_id = 123

Person.find_by_id(123)
#=> your person (by column `id`) or nil

Person.filter('last_name = ? AND first_name LIKE ?',
              "Saget", "B%")
#=> array of persons with last_name of Saget and first_name starting with B

Task.find(456).person.first_name
#=> Load task with `id` 456, then request Person with `id` (if task.person_id isn't nil)
#   This task's person is cached on the task itself, but there is no identity map
#   so all Task.find(456) calls will call the server again.

Implementing your own filter methods are easy:

class Task < BaseModel
  exposed_as 'tasks'

  # Assume the returned task has a person_id column and the class_name is Person
  belongs_to :person

  def self.completed_for_person(person)
    filter('person_id = ? AND completed = 1', person.id)
  end

  def self.next_for_person(person)
    # NOTE: Currently, this pulls back ALL the items maching the query and only
    #       then selects the first task
    filter('person_id = ? AND completed = 0', person.id).first
  end
end

TODO

• Tests
• Smarter relations
  • Has one
  • Offsets and limits
• Other missing common SQL (i.e. Sequel) functionality
• Improve configuration options
  • HTTP Auth and security
  • Alternate output formats/content types
  • Primary keys other than id
• Better documentation

Contributing

• Fork this repository
• Make your changes and submit a pull request

License

Copyright (c) 2012 Doug Mayer. Distributed under the MIT License. See MIT-LICENSE for further details.