schemation

Schema grammar

import {any, boolean, number, string} from "schemation"
import {and, not, or}                 from "schemation"
import {where}                        from "schemation"
import {optional}                     from "schemation"
import {lazy}                         from "schemation"

   <schema> ::= <class>
              | <lazy>
              | <logical>
              | <predicate>
              | <shape>
 
    <class> ::= any
              | boolean
              | number
              | string
 
     <lazy> ::= lazy( () => <schema> )
 
  <logical> ::= and( <schema>, ... )
              | not( <schema> )
              |  or( <schema>, ... )
 
<predicate> ::= /.../
              | where( <unary-predicate> )
 
    <shape> ::= false | true
              | "..."
              | <number>
              | [ <schema> ]
              | null
              | { <property>, ... }
 
 <property> ::= "...":           <schema>
              | "...": optional( <schema> )

Entry points

import {matches, tryMatch, validate} from "schemation"

matches(schema)(json)
  => true
   | false

tryMatch(schema, onMatch, onMismatch)(json)
  => onMatch(json)
   | onMismatch(mismatch)

validate(schema)(json)
  => json
   | throw new Error(mismatch)

Mismatches

import {Mismatch, MismatchAt, Mismatches} from "schemation"

mismatch ::= Mismatch {value}
           | MismatchAt {mismatch, index}
           | Mismatches {mismatches}

mismatch.toString()

Extending

For example, given

const empty = where(x => x.length === 0)

the expression

and([any], not(empty))

matches any non-empty array.

Example

const SetOfProducts = [
  {
    id: number,
    name: string,
    price: and(number, where(x => 0 < x)),
    tags: optional(and([string], not(empty))),
    dimensions: optional({
      length: number,
      width: number,
      height: number
    }),
    warehouselocation: optional({
      latitude: number,
      longitude: number
    })
  }
]