json-schema-validator-generator
A Flow type and JS validator code generator for JSON Schema.
Install
yarn add json-schema-validator-generator
Usage
Basic
import generate from 'json-schema-validator-generator';
const schema = {type: 'string'};
const {flow, js} = generate(schema);
console.log(flow);
// declare type root = string;
console.log(js);
// (function() {
// function f0(v0) {
// if (typeof v0 !== 'string') {
// return 1;
// }
// return 0;
// }
// return {
// root: f0,
// };
// })()Flow Output
The generated flow string is meant for direct consumption in a project's library definitions. See scripts/generate.js for an example script which writes flow types to src/decls/json-schema.js.
JS Output
The generated JS string is an IIFE that evaluates to an object whose values are validator functions. Each validator returns a number with 0 representing a valid model and a nonzero number otherwise.
type Validator = (data: mixed) => number;It's recommended to write the generated JS to the filesystem, but it's possible to use the generated code at runtime.
Static JS Usage
See scripts/generate.js for an example script which writes validators to src/generated-validator.js.
Dynamic JS Usage (not recommended)
import generate from 'json-schema-validator-generator';
const validatorForSchema = (schema) => {
const {js} = generate(schema);
return eval(js);
};Advanced
Sometimes we may be using JSON Schema to define a collection of types. In this case, the generator needs some information about the subschema to be generated.
For example, consider the definition of a binary tree of numbers:
import generate from 'json-schema-validator-generator';
const schema = {
definitions: {
node: {
type: 'object',
properties: {
left: {$ref: '#/definitions/nodeOrValue'},
right: {$ref: '#/definitions/nodeOrValue'},
},
required: ['left', 'right'],
},
nodeOrValue: {
oneOf: [
{$ref: '#/definitions/node'},
{type: 'number'},
],
},
},
};
const {flow, js} = generate(schema, {node: schema.definitions.node});
const nodeValidator = eval(js).node;
console.log(nodeValidator({left: 1, right: 2})); // 0
console.log(nodeValidator({left: 1, right: {left: 2, right: 3}})); // 0
console.log(nodeValidator(1)); // error
console.log(nodeValidator({left: 1})); // error
console.log(nodeValidator({left: 1, right: '2'})); // error
