rules (node.js)

Small declarative rules framework designed primarily for use when validating incoming data, such as JSON coming into services.

Samples

You create an object to declare the rules/invariants you want to apply (something akin to a schema). A fluent interface makes it easy to specify the invariants for each property:

#####JavaScript

var personRules = {
    name:        mustBe().populated().string( { minLength: 5, maxLength: 20} ), [1]
    weight:      mustBe().populated().numeric({min : 0, max: 130}),
    dateOfBirth: mustBe().date({ before: now.subtract("years", 1) })
}

#####CoffeeScript

# This schema is not showing how to validate a real address, its just an example that makes it easy to test the framework
addressRules = {
  streetOne: mustBe().populated()
  streetTwo: -> @.populated().string( minLength: 10, maxLength : 50 ) [2]
  streetThree: -> @.populated().string( minLength : 10, maxLength: 50) 
  town: -> @.populated()
  postCode: -> @.populated().matchFor(/.../)
}

As shown you can access this fluent interface using twp approaces:

• [1] mustBe() - Acts as the entry point to the fluent interface.
• [2] function - 'this' inside the function being the entry point to the fluent interface.

#####Triggering validation You trigger validation using:

result = rules.apply(person, personRules)

The returned object has the per-property details of any validation failures, e.g.:

{ town: 
   [ { message: 'The value must be populated.',
       type: 'not_populated',
       value: undefined } ] 
}

Examples

The project comes with examples in the examples directory:

node examples/person
coffee examples/address

Note that if you are using sublime you can get the alignment shown in the person example using the sublime text alignment package.

Validators

The framework comes with several validators, to understand them further you may want to run the examples.

• populated - Checks the value is not null, undefined, "", or an empty array.
• array
• numeric - Optionally you can also pass in object with min and/or max values
• matchFor - You can pass in an object with pattern and optionally flags, alternatively you can pass in the RegExp object to use.
• date - Optionally you can specify that the date must be before and/or after specified dates. To make this easier you use now.add or now.subtract to specify the dates to use for before/after.
• string - Optionally you can pass in minLength and/or maxLength.

Tests

First install mocha:

npm install mocha -g

Run the tests:

mocha -R spec spec/ -w -G --recursive -b

Future

• More validators
• Potentially UMD support