Validarkjs

Simple Data Validation Library

Usage

Call the validate method with the required schema and the records to be validated:

import { validate } from validark

const schema = {
    "*name": String,
    "age": parseInt
}

const records = [{
    "name": "Pepito Pérez",
    "age": 64
}]

const [result] = validate(schema, records)

console.assert(result === value)

Schemas are just objects whose keys are strings and whose records are validation callables, objects or arrays. e.g.:

const schema = {
    "color": String,
    "width": parseInt,
    "height": parseInt,
    "weight": parseFloat,
    "duration": (v) => (v >= 0 && v <= 59) && v || 0
    "contact": {
        "phone": String,
        "email": (v) => v.contains('@') && v || ''
    }
}

Validation callables must receive their keys' corresponding input value and return the final value that will be assigned to such key. If an Error is received, it will be thrown:

const schema = {
    "name": String,
    "age": (v) => (v > 0 && v < 130) && v || new Error("Invalid Age!")
}

const message = None

try {
    const records = [{"name": "John Doe", "age": 200}]
    const [result] = validate(schema, records)
} catch (error) {
    const message = String(error)
}

console.assert(message === "Error: Invalid Age!")

Mandatory fields can be marked with an asterix (*) as key prefix:

const schema = {
    "title": String,
    "*firstname": String,
    "*surname": String,
}

Aliases can be delimited with :=. The final key will be the leftmost entry:

const schema = {
    "*first_name:=firstname:=firstName": String,
    "*last_name:=lastname:=lastName": String
}

const records = [
    {"firstName": "Clark", "lastName": "Kent"},
    {"firstname": "Peter", "lastname": "Parker"},
    {"first_name": "Bruce", "last_name": "Wayne"}
]

const result = validate(schema, records)

console.assert(result === [
    {"first_name": "Clark", "last_name": "Kent"},
    {"first_name": "Peter", "last_name": "Parker"},
    {"first_name": "Bruce", "last_name": "Wayne"}
])

Extra keys in the records' entries are ignored and aliases definitions are processed from right to left if there are multiple matches:

const schema = {
    "*name": String,
    "*player_id:=playerId": String,
    "*score:=totalScore:=points": parseInt
}

const records = [
    {"name": "James", "playerId": "007", "totalScore": 99, "points": 55}
]

const [result] = validate(schema, records)

console.assert(result === {
    "name": "James", "player_id": "007", "score": 99
})

Sequences of items might be handled by defining the validation function inside an array:

const schema = {
    "levels": [String],
    "addresses": [
        {'*street': String, 'city': String}
    ]
}

const records = [{
    "levels": [1, 2, 3],
    "addresses": [
        {"street": '5th Ave 45', "city": "Popeland"},
        {"street": '7th Street 67', "city": "Churchland"}
    ]
}]

const [result] = validate(schema, records)

console.assert(result === {
    "levels": ["1", "2", "3"],
    "addresses": [
        {"street": '5th Ave 45', "city": "Popeland"},
        {"street": '7th Street 67', "city": "Churchland"}
    ]
})

Utilities

Validark includes several utility functions to simplify common validation scenarios.

check

The check() function behaves similarly to the assert() function in NodeJS. However, this function is provided as a convenient multi-environment utility. check() returns the provided value if it is truthy.

const value = 'Truthy Value'

const result = check(value)

const [result] = validate(schema, records)

console.assert(result === value)

In the other hand, if the value provided to check is falsy, it raises an error with the optional provided message.

const value = undefined

try {
  check(value, 'Invalid Value!')
} catch (error) {
  const message = String(error)
}

console.assert(message === "check failed. Invalid Value!")

Or called without arguments:

try {
  check()
} catch (error) {
  const message = String(error)
}

console.assert(message === "check failed.")

grab

The grab() retrieves a key from an object.

const object = {
  element: 'content'
}

const result = grab(object, 'element')

console.assert(result === "content")

It errors out if the key is not found in the object.

const object = {
  element: 'content'
}

try {
  grab(object, 'missing')
} catch (error) {
  const message = String(error)
}

console.assert(message === 'Key "missing" not found')

It can also provide a fallback value in case the key is not found in the container object.

const object = {
  element: 'content'
}

const value =  grab(object, 'missing', 777)

console.assert(value === 777)

The grab() function can also receive a Class as its key argument. In that case, an instance of such class will be tried to be obtained from the provided object container. The name of the key wold be either the name of the class in camelCase or just its unaltered string name.

class Alpha {}

const object = {
  alpha: new Alpha()
}

const value = grab(object, Alpha)

console.assert(value instanceof Alpha)