Schema

SCHEMA –

USERS
  t:integer id
  t:string username
  t:string password_digest
  t:string session_token

  timestamps

MESSAGES
  t:integer id
  t:integer author_id FOREIGN_KEY
  t:integer context_id FOREIGN_KEY
    (could refer to another message/a channel/a direct message [polymorphic?])
  t:text body

  timestamps

ORGANIZATIONS
  t:integer id
  t:string title
  t:text description

  timestamps

CHANNELS/CHATS
  t:integer id
  t:string title
  t:integer organization_id
  t:text description

  timestamps

JOIN TABLES

CHANNELS/CHATS_USERS
  t:integer user_id FOREIGN_KEY
  t:integer channel_id FOREIGN_KEY

  timestamps

ORGANIZATIONS_USERS
  t:integer user_id FOREIGN_KEY
  t:integer organization_id FOREIGN_KEY

  timestamps