DML 2.0

Models

Every model consists of one or more declarative rules (see this project for a nodejs reference implementation that also works in the browser).

Models are compiled to a cachable json structure that is used to validate data.

Rules

Every rule in a model is defined by at least a type and a path. The type describes what kind of data is expected and the path describes where to find it. Consider the following data and model.

example.json

{
  created: 1480801018654,
  user: {
    name: 'Glen Danzig'
  }
}

example.model

Date created
String user.name

A rule can also have a default error message.

Date created "Must be a valid date"

Validators

In addition to a type, a rule can have zero or more validators. A validator is a function (it is possible to create custom validators). Validators are declared inside curly braces immediately following the type and path. A validator has two or more parts — a function name, a value, and an optional error message. The data must satisfy criteria defined by the rule's validators.

example.model

String user.name
  required
  gt 2 "Must be greater than 2 characters"
  lte 256 "Must be less than or equal to 256 characters"

Rules that have validators can also have a default error message.

String user.name "Must be a valid name"
  required true

Built-in validators can also handle relative and absolute dates.

Date birthday
  gt +1week "Must be greater than one week from now"

Built-in validators can also handle regular expressions.

String uuid
  regExp /[0-9]{1,3}.[0-9]{1,3}/

Comments

C-style inline comments are supported.

Date created
Number id

String name
  required true // this is a comment
  gt 2 "Must be greater than 2 characters"
  lte 256 "Must be less than or equal to 256 characters"

String bio "A bio must be a string"
  lte 140 "A bio must fit into a tweet"

Boolean accountType
        

Custom Types

Often you need to define a single type that you will use accross more than one model.

example.model

def Password
  type String
  gte 3
  lte 15
  regexp /\d+/ "must contain at least one digit"

Password mypass
  require 'a pwd is reqd'

Directives

A model can contain the @clean directive which will ensure that any values not defined in the model are removed from the result.

input.json

{
  created: 1480801018654,
  height: 'Short, AF',
  user: {
    name: 'Glen Danzig'
  }
}

example.model

@clean
Date created
String user.name

Given the above data and model, the result will not include the height property.

output.json

{
  created: '2016-10-02T13:56:44.931Z',
  user: {
    name: 'Glen Danzig'
  }
}