@smallwins/validate

Parameter validation for builtins and custom types. Accepts params and a schema and returns an array of Errors or false.

var validate = require('@smallwins/validate')

function hi(params, callback) {
  var schema = {
    'name':       {required:true,  type:Object},
    'name.first': {required:true,  type:String},
    'name.last':  {required:false, type:String}
  }
  var errors = validate(params, schema) 
  if (errors) {
    callback(errors)
  }
  else {
    callback(null, 'hi ' + params.first)
  }
}

// logs: null, hi brian
hi({name:{first:'brian', last:'leroux'}}, console.log)

// logs: [ [ReferenceError: missing required param name.first] ] 
hi({name:{}}, console.log)

considerations

For testing an Object that presumably came from a JSON payload
Thusly, primarily concerned with JSON value types: Object, String, Number, Array and Boolean
Custom types are easily supported (see ./examples)
Designed to test keys and nested keys
Optionally validate required
Optionally validate min and max for String, Number and Array builtin types (and easily implement for custom types)

things it does not do

Mutate things with: serialization, formatting or defaults
Nested subtypes (eg. the things in an array)
Localized error messages

further justifications

There are a tonne of libraries that do things like this but also do a whole lot more. This library deliberately limits its scope:

Make errback style param contract validation super clean and simple
Work primarily with builtins but easily extend
Provide a nice API for usage (hence returning false instead of a truthy empty array for the return value of validate)

another example usage

var validate = require('@smallwins/validate')

functon sum(params, callback) {
  // define our assumed params
  var errors = validate(params, {
    x: {required:true, type:Number},
    y: {required:true, type:Number}
  })
  // err first!
  if (errors) {
    callback(errors)
  }
  else {
    callback(null, params.x + params.y)
  }
}

api

validate(params, schema)

params a plain Object that we assume came from JSON
schema a plain Object for describing the shape of the data
callback (optional) Node style errback function(err, params) {}

schema keys

required either true or false (or leave it out completely)
type can be one of Object, String, Number, Array and Boolean
min any Number (or anything allowed by a custom type)
max any Number (or anything allowed by a custom type)

Check out the examples for more on custom types and ranges (and the tests).