An API for validation that I would like...

gistfile1.coffee

#empty validator
validator = new Validator()

#custom app validator
validator.constraint 'unique-name', (val, ops = {}) ->
  namelist = [] #... array of names in system
  return "Name already exists!" if namelist.indexOf val > -1
  return true

#another custom validator    
validator.constraint 'phone-number', (val, ops = {}) ->
  #... custom phone number validation
  
  return true

#define schema for object
validator.schema 'user'
  .prop 'firstName'
    .constrain 'type', 'string'
    .constrain 'required'
    .constrain 'unique-name'
  .prop 'email',
    .constrain 'email'
    .constrain 'required'
  .prop 'mailingAddress'
    .constrain 'schema', 'address'
  .prop 'phone'
    .constrain 'phone-number'
  .prop 'previousAddresses'
    .constrain 'type', 'array'
    .constrain 'length', min: 1
    .constrain 'each', name: 'schema', options: 'address'

#schema for nested object, the "schema" constraint means apply this schema to a sub-object
validator.schema 'address'
  .constrain 'us-address'   #constraint can be on entire object, or specific property
  .prop 'street'
    .constrain 'required'
  .prop 'city'
    .constrain 'required'
  .prop 'areaCode'
    .constrain 'required'

#an structure to validate
user =
  firstName: "Foobert"
  email: 'foobaz@gmail.net'
  phone: '333-333-3333'
  primaryAddress:
    street: 'foo'
    city: 'bar'
    areaCode: 90210
  previousAddresses: [
    {street: '1828 L ST NW', city: 'Anytown', areaCode: 44455}
    {street: '1828 L ST NW', city: 'Anytown', areaCode: 44455}
  ]

# would throw an error if a constraint returns a promise
errors = validator.validate 'user', user

# will return already resolved promise if nothing was actually async
promise = validator.validateAsync 'user', user
promise.then (errors) ->
  #do stuff

#use a specific validator on a specific value
errors = validator.validateValue '333-456-2435', 'phone-number', {}