json-schema-walker

What is json-schema-walker?

The json-schema-walker package is a utility for traversing JSON schemas. It allows developers to walk through JSON schema objects and perform operations on each node, which is useful for tasks such as validation, transformation, or analysis of JSON schemas.

What are json-schema-walker's main functionalities?

Schema Traversal

This feature allows you to traverse a JSON schema and perform operations on each node. In the code sample, the walker function is used to iterate over each node in the schema, printing the pointer (path) to each node.

const walker = require('json-schema-walker');

const schema = {
  type: 'object',
  properties: {
    name: { type: 'string' },
    age: { type: 'integer' }
  }
};

walker(schema, {
  all: (subSchema, pointer) => {
    console.log('Visiting:', pointer);
  }
});

Custom Node Processing

This feature allows you to apply custom logic to nodes based on their properties. In the code sample, the walker function is used to identify nodes of type 'string' and print their path.

const walker = require('json-schema-walker');

const schema = {
  type: 'object',
  properties: {
    name: { type: 'string' },
    age: { type: 'integer' }
  }
};

walker(schema, {
  all: (subSchema, pointer) => {
    if (subSchema.type === 'string') {
      console.log('String type found at:', pointer);
    }
  }
});

Other packages similar to json-schema-walker

json-schema-traverse

json-schema-traverse is a similar package that provides functionality to traverse JSON schemas. It offers a more flexible API for visiting nodes and allows for pre- and post-order traversal. Compared to json-schema-walker, json-schema-traverse might offer more control over the traversal process.

ajv

Ajv is a JSON schema validator that also includes functionality for traversing schemas. While its primary purpose is validation, it can be used to walk through schemas as part of the validation process. Ajv is more feature-rich and includes validation, compilation, and transformation capabilities, making it a more comprehensive tool compared to json-schema-walker.

README

JSON Schema Walker

Loosely based on CloudFlare's json schema tools

A system that visits all schema objects in a JSON Schema document and makes callbacks before and/or after visiting all of the current schema object's subschemas.

Usage

import { Walker } from "json-schema-walker";
const schema = {
  // your json schema
};
const walker = new Walker<T>();
await walker.loadSchema(schema, {
  cloneSchema: true,
  dereference: false,
  dereferenceOptions: {
    dereference: {
      circular: "ignore",
    },
  },
});
const convertSchema = (schema) => {
  // do something with the schema properties
};
await walker.walk(convertSchema, walker.vocabularies.DRAFT_07);
const updatedSchema = walker.rootSchema;

Circular references

Passing the options

{
  "dereferenceOptions": {
    "dereference": {
      "circular": "ignore"
    }
  }
}

will dereference all non-circular references in your schema.