json-schema-library

json-schema-library

Customizable and hackable json-validator and json-schema utilities for traversal, data generation and validation

This package offers tools and utilities to work with json-schema, create and validate data. Unfortunately, most packages, editors or validators do not care to expose basic json-schema functionality. Instead of small memory footprint or high performance, this package focuses on exposing utilities for browser and node environments and lessens the pain to build custom tools around json-schema.

npm i json-schema-library.

This package is tested on node v6.9.1.

Overview

Either select an existing validator (core) or create your own. Each Core hold all functions that are required for the json-schema operations like validation. In order to overwrite a custom function you can either

• modify the map-objects (i.e. /lib/validation/keywords)
• overwrite functions or keys in the generated instance (const instance = new Core())
• Create a custom Core following the examples in /lib/cores

Additionally, helper functions and tools are separately exposed via CommonJS Modules. Most of them do require a core-object as parameter, but use only some of the functions defined in an core-instance.

Core

The default interface of a validator can be found in /lib/cores/CoreInterface. It exposes the following methods

method	parameter	description
constructor	schema	pass the root schema in the constructor
get rootSchema		or pass the root schema as property like
set rootSchema	rootSchema	instance.rootSchema = require("./json-schema.json")
each	schema, data, callback, pointer = "#"	Iterates over the data, passing value and its schema
step	key, schema, data, pointer = "#"	step into a json-schema by the given key (property or index)
validate	schema, data, pointer = "#"	return a list of errors found validating the data
isValid	schema, data, pointer = "#"	returns true if the data is validated by the json-schema
resolveOneOf	schema, data, pointer = "#"	returns the oneOf-schema for the passed data
resolveRef	schema	resolves a $ref on a given schema-object
getSchema	schema, data, pointer = "#"	returns the json schema of the given data-json-pointer
getTemplate	schema, data	returns a template object based of the given json-schema

examples

getSchema(core, schema, pointer, data)

return the json 'schema' matching 'data' at 'pointer'. Should be modified to use a step/next-function, which is already within the logic (advance VS retrieve from root -> support both)

const core = new require("json-schema-library").core.draft04(rootSchema),
const targetSchema = getSchema(core, rootSchema, '#/path/to/target', rootData);

Currently may also return an error:

if (targetSchema instanceOf Error) {
    throw targetSchema;
}

getTemplate(core, schema, data, rootSchema = schema)

return data which is valid to the given json-schema. Additionally, a data object may be given, which will be extended by any missing items or properties.

const baseData = getTemplate(
    { type: "object", properties: { target: { type: "string", default: "v" } } },
    { other: true }
); // returns { other: true, target: "v" }

validate(data, schema, step)

returns a list of validation errors

const core = new require("json-schema-library").core.draft04(rootSchema),
const baseSchema = core.validate({ type: "number" }, "");
// returns false

// alternatively use core.validate({ type: "number" }, "")

isValid(data, schema, step)

returns true if the given schema validates the data

const core = new require("json-schema-library").core.draft04(rootSchema),
const baseSchema = core.isValid({ type: "number" }, "");
// returns false

step(key, schema, data, rootSchema = schema)

returns the child schema found at the given key

const core = new require("json-schema-library").core.draft04(rootSchema),
const baseSchema = core.step(
    { type: "object", properties: { target: {type: "string"}} },
    { target: "value" }
    "target", 
); // returns {type: "string"}

// alternatively use core.step({ type: "object", properties: { target: {type: "string"}} }, { target: "value" }, "target")

each(data, schema, callback)

calls the callback on each item (object, array and value), passing the current schema and its data

const rootSchema = {
    type: "array",
    items: [
        { type: "number" },
        { type: "string" }
    ]
};
const core = new require("json-schema-library").core.draft04(rootSchema),
core.each(core.rootSchema, [5, "nine"], (schema, value, pointer) => {
    // 1. schema = { type: "array", items: [...] }, data = [5, "nine"], pointer = #
    // 2. schema = { type: "number" }, data = 5, pointer = #/0
    // 3. schema = { type: "string" }, data = "nine", pointer = #/1
});

Additional helpers

SchemaService(schema)

binds the schema to getSchema.

const schemaService = new SchemaService(rootSchema); // default core 'draft04'
const targetSchema = schemaService.get('#/path/to/target', rootData);

createSchemaOf(data)

returns a json schema which is valid against data.

const baseSchema = getTemplate({ target: "" });
// returns {type: "object", properties: { target: "string"}},