SHACL To JSON Schema

This is a simple library to translate SHACL NodeShapes into JSON Schemas. It does not support the full SHACL vocabulary, only those fields which can be applied to JSON Schema.

Install

npm install @comake/shacl-to-json-schema

Usage

The nodeShapeToJSONSchema function exported by this library supports converting SHACL NodeShapes encoded as JSON-LD into JSON Schema.

For example, using Typescript:

import { nodeShapeToJSONSchema } from '@comake/shacl-to-json-schema';

const nodeShape = {
  '@type': 'shacl:NodeShape',
  'http://www.w3.org/ns/shacl#targetClass': 'https://example.com/Class',
  'http://www.w3.org/ns/shacl#property': [
    {
      'http://www.w3.org/ns/shacl#datatype': {
        '@id': 'http://www.w3.org/2001/XMLSchema#string'
      },
      'http://www.w3.org/ns/shacl#maxCount': {
        '@value': 1,
        '@type': 'http://www.w3.org/2001/XMLSchema#integer'
      },
      'http://www.w3.org/ns/shacl#name': {
        '@value': 'field',
        '@type': 'http://www.w3.org/2001/XMLSchema#string'
      }
      'http://www.w3.org/ns/shacl#path': {
        '@id': 'https://example.com/field'
      }
    }
  ]
};

const schema = nodeShapeToJSONSchema(nodeShape);
console.log(schema);

// Output:
// {
//   type: 'object',
//   properties: {
//     'https://example.com/field': { 
//       type: 'string'
//     }
//   }
// }

By default the shacl:path of each property will be used as the property key in the resulting JSON Schema. If instead you need the generated JSON Schema to use the shacl:name field as property keys, set the useNames option to true:

const schema = nodeShapeToJSONSchema(nodeShape, { useNames: true });
console.log(schema);

// Output:
// {
//   type: 'object',
//   properties: {
//     field: {   <---- Uses "field" instead of "https://example.com/field"
//       type: 'string'
//     }
//   }
// }

Support

Currently this library only supports properties that include a shacl:datatype, shacl:node, or shacl:nodeKind.

Supported shacl:datatype values:

• xsd:string generates a JSON Schema with type string
• xsd:integer generates a JSON Schema with type integer
• xsd:negativeInteger generates a JSON Schema with type integer
• xsd:positiveInteger generates a JSON Schema with type integer
• xsd:int generates a JSON Schema with type integer
• xsd:decimal generates a JSON Schema with type number
• xsd:float generates a JSON Schema with type number
• xsd:double generates a JSON Schema with type number
• xsd:boolean generates a JSON Schema with type boolean
• xsd:dateTime generates a JSON Schema with type string and format data-time
• xsd:date generates a JSON Schema with type string and format date
• xsd:time generates a JSON Schema with type string and format time
• rdf:JSON generates a JSON Schema with type string, number, boolean, object, or array

Supported shacl:nodeKind values:

• sh:BlankNode generates a JSON Schema with type object
• sh:IRI generates a JSON Schema with type string
• sh:Literal generates a JSON Schema with type string, number, boolean, object, or array
• sh:BlankNodeOrIRI generates a JSON Schema with type string or object
• sh:BlankNodeOrLiteral generates a JSON Schema with type string, number, boolean, object, or array
• sh:IRIOrLiteral generates a JSON Schema with type string, number, boolean, object, or array

Support for shacl:maxLength, which adds maxLength to the resulting JSON Schema property when the shacl:datatype is one of:

• xsd:string
• xsd:dateTime
• xsd:date
• xsd:time

Support for shacl:in for all datatypes, which produces a JSON Schema enum

Support for shacl:minExclusive, shacl:minInclusive, shacl:maxExclusive, shacl:maxInclusive for all numeric datatypes

Optional support for shacl:name and shacl:description when the options addTitles or addDescriptions are set to true, respectively. Doing so will add JSON Schema title and description to the resulting properties.

Support for shacl:minCount and shacl:maxCount:

• If shacl:maxCount is unset or greater than 1, the property will be treated as an array. If so, shacl:maxCount and shacl:minCount values are used to set maxItems and minItems in the resulting JSON Schema.
• If shacl:minCount is greater than 0, the property will be required in the resulting JSON Schema

Support for shacl:closed. When true, the resulting JSON Schema will have additionalProperties set to false.

Not Supported

No support for SHACL predicates shacl:lessThanOrEquals, shacl:lessThan, shacl:flag, shacl:equal, shacl:class, and shacl:languageIn.

There is also currently no support for complex SHACL Property Paths including Sequence Paths, Alternative Paths, Inverse Paths, Zero-Or-More Paths, One-Or-More Paths, and Zero-Or-One Paths.

API

nodeShapeToJSONSchema

Converts SHACL NodeShapes encoded as JSON-LD into JSON Schema.

Parameters

Parameter	Type	Required	Description
shape	JSON	Required	The SHACL NodeShape to convert encoded as JSON-LD.
options	object		A ConversionOptions object (see below).

ConversionOptions

These are the available options to configure the behavior of the conversion (in Typescript):

interface ConversionOptions {
  /**
   * When true, the names of fields in the generated JSON Schema 
   * will use the shacl:name of each property instead of the shacl:path uri
   */
  useNames?: boolean;
  /**
   * When true, each field will include a title equal 
   * to it's corresponding property's shacl:name
   */
  addTitles?: boolean;
  /**
   * When true, each field will include a description equal 
   * to it's corresponding property's shacl:description
   */
  addDescriptions?: boolean;
}

Return Value

A JSON Schema object