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

Examples

getSchema(core, schema, pointer, data)

Returns 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)

Returns 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 Core = require("json-schema-library").cores.Draft04;
const core = new Core();
const baseData = core.getTemplate(
    { type: "object", properties: { target: { type: "string", default: "v" } } },
    { other: true }
); // returns { other: true, target: "v" }

validate(core, data, schema, step)

Validate data and get a list of validation errors

const Core = require("json-schema-library").cores.Draft04;
const core = new Core(rootSchema);
const errors = core.validate({ type: "number" }, "");
// returns [TypeError]

isValid(core, data, schema, step)

Return true if the given schema validates the data

const Core = require("json-schema-library").cores.Draft04;
const core = new Core(rootSchema);
const baseSchema = core.isValid({ type: "number" }, "");
// returns false

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

Get the child schema of a property or index

const Core = require("json-schema-library").cores.Draft04;
const core = new Core(rootSchema);
const baseSchema = core.step(
    { type: "object", properties: { target: {type: "string"}} },
    { target: "value" }
    "target", 
); // returns {type: "string"}

each(core, data, schema, callback)

Iterate over each item (object, array and value), passing each value and its corresponding schema

const Core = require("json-schema-library").cores.Draft04;
const core = new Core({
    type: "array",
    items: [
        { type: "number" },
        { type: "string" }
    ]
});
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)

Retrieve the json-schema at the given json-pointer

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

createSchemaOf(data)

Creates a json-schema for the given input-data.

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