json-schema-traverse

Traverse JSON Schema passing each schema object to callback

Install

npm install json-schema-traverse

Usage

const traverse = require('json-schema-traverse');
const schema = {
  properties: {
    foo: {type: 'string'},
    bar: {type: 'integer'}
  }
};
 
traverse(schema, {cb});
// cb is called 3 times with:
// 1. root schema
// 2. {type: 'string'}
// 3. {type: 'integer'}
 
// Or:
 
traverse(schema, {cb: {pre, post}});
// pre is called 3 times with:
// 1. root schema
// 2. {type: 'string'}
// 3. {type: 'integer'}
//
// post is called 3 times with:
// 1. {type: 'string'}
// 2. {type: 'integer'}
// 3. root schema
 

Callback function cb is called for each schema object (not including draft-06 boolean schemas), including the root schema, in pre-order traversal. Schema references ($ref) are not resolved, they are passed as is. Alternatively, you can pass a {pre, post} object as cb, and then pre will be called before traversing child elements, and post will be called after all child elements have been traversed.

Callback is passed these parameters:

• schema: the current schema object
• JSON pointer: from the root schema to the current schema object
• root schema: the schema passed to traverse object
• parent JSON pointer: from the root schema to the parent schema object (see below)
• parent keyword: the keyword inside which this schema appears (e.g. properties, anyOf, etc.)
• parent schema: not necessarily parent object/array; in the example above the parent schema for {type: 'string'} is the root schema
• index/property: index or property name in the array/object containing multiple schemas; in the example above for {type: 'string'} the property name is 'foo'

Traverse objects in all unknown keywords

const traverse = require('json-schema-traverse');
const schema = {
  mySchema: {
    minimum: 1,
    maximum: 2
  }
};
 
traverse(schema, {allKeys: true, cb});
// cb is called 2 times with:
// 1. root schema
// 2. mySchema

Without option allKeys: true callback will be called only with root schema.

License

MIT