Schematized

Turn objects into JSON schemas! The more examples you provide, the better your schema will be.

A Node port of the Python module GenSON but with more inferred constraints.

Example use case: Generate JSON schemas using your API tests, then use the schemas to validate. To keep up to date, Write a test that compares your current schema with the generated schema. Then when your API changes, just update the tests with the newly generated schemas and move on with your day.

• Schematized
  • :rocket: Quick start
    • Schema from the single example
    • Schema from the two examples
    • Schema from the two examples and the schema
  • :books: API
  • :dart: Supported Schema Features
    • Types
    • Typeless
    • String
      • Supported String formats
    • Number
    • Object
    • Array

:rocket: Quick start

1. Add dependency

yarn add schematized

2. Basic usage : See output

import SchemaBuilder from 'schematized' // Typescript & ESM
const { default: SchemaBuilder } = require('schematized') // CommonJS

const builder = new SchemaBuilder()

// Consume JSON
builder.addObject({
  token: '74aea1a53d68b77e4f1f55fa90a7eb81',
  role: ['Basic'],
})

// Produce JSON Schemas!
const schema = builder.toPrettySchema()

3. Improve the schema with examples : See output

...

builder.addObject({
  token: 'Bearer 6498d9afc96d1d8d881a2b7ded4f9290',
  role: [
    'Admin',
    'Basic',
    'Publisher'
  ]
})

4. Improve the schema with existing schemas : See output

...

builder.addSchema({
  title: '/user server response',
  description: '/user server response'
})

Schema from the single example

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "token": {
      "type": "string",
      "maxLength": 32,
      "minLength": 32
    },
    "role": {
      "type": "array",
      "items": {
        "type": "string",
        "maxLength": 5,
        "minLength": 5
      }
    }
  },
  "required": [
    "role",
    "token"
  ],
  "additionalProperties": false,
  "maxProperties": 2,
  "minProperties": 2
}

Schema from the two examples

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "token": {
      "type": "string",
      "maxLength": 39,
      "minLength": 32
    },
    "role": {
      "type": "array",
      "items": {
        "type": "string",
        "maxLength": 9,
        "minLength": 5
      }
    }
  },
  "required": [
    "role",
    "token"
  ],
  "additionalProperties": false,
  "maxProperties": 2,
  "minProperties": 2
}

Schema from the two examples and the schema

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "/user server response",
  "description": "/user server response",
  "type": "object",
  "properties": {
    "token": {
      "type": "string",
      "maxLength": 39,
      "minLength": 32
    },
    "role": {
      "type": "array",
      "items": {
        "type": "string",
        "maxLength": 9,
        "minLength": 5
      }
    }
  },
  "required": [
    "role",
    "token"
  ],
  "additionalProperties": false,
  "maxProperties": 2,
  "minProperties": 2
}

:books: API

| Method | Definition | Parameter | | --------------------- | ----------------------------------------------- | ----------------- | | .addObject($object) | Add an example to improve the generated schema. | Valid JSON object | | .addSchema($schema) | Add schemas to improve the generated schema. | Valid JSON Schema | | .toSchema() | Generate the schema. | None | | .toPrettySchema() | Generate the schema and pretty print. | None |

:dart: Supported Schema Features

Visit the official JSON Schema site for specification details.

Types

| Type | Supported | | ------- | --------- | | String | Yes | | Number | Yes | | Integer | Never | | Object | Yes | | Array | Yes | | Tuple | Not yet | | Boolean | Yes | | Null | Yes |

Typeless

| Constraint | addSchema() | addObject() | | ------------ | ----------- | ----------- | | title | Yes | Never | | description | Yes | Never | | $comment | Yes | Never | | default | Not yet | Not yet | | examples | Not yet | Not yet | | enum | Not yet | Not yet | | const | Not yet | Not yet | | anyOf | Yes | Yes | | allOf | Not yet | Not yet | | oneOf | Not yet | Not yet | | not | Not yet | Not yet | | if/then/else | Not yet | Not yet |

String

| Constraint | addSchema() | addObject() | | ---------------- | ----------- | ----------- | | maxLength | Yes | Yes | | minLength | Yes | Yes | | format | Yes | Yes | | pattern | Not yet | Not yet | | contentMediaType | Not yet | Not yet | | contentEncoding | Not yet | Not yet |

Supported String formats

| Format | Supported? | | --------------------- | ---------- | | date-time | Yes | | date | Yes | | time | Yes | | email | Yes | | hostname | Not yet | | idn-hostname | Not yet | | ipv4 | Yes | | ipv6 | Yes | | uri | Yes | | uri-reference | Not yet | | url | Yes | | uuid | Yes | | iri | Not yet | | iri-reference | Not yet | | uri-template | Not yet | | json-pointer | Not yet | | relative-json-pointer | Not yet | | regex | Not yet |

Number

| Constraint | addSchema() | addObject() | | ---------------- | ----------- | ----------- | | maximum | Yes | Yes | | minimum | Yes | Yes | | exclusiveMaximum | Not yet | Not yet | | exclusiveMinimum | Not yet | Not yet | | multiple | Not yet | Not yet |

Object

| Constraint | addSchema() | addObject() | | -------------------- | ----------- | ----------- | | propertyPatterns | Yes | Yes | | additionalProperties | Yes | Yes | | required | Yes | Yes | | maxProperties | Yes | Yes | | minProperties | Yes | Yes |

Array

| Constraint | addSchema() | addObject() | | ----------- | ----------- | ----------- | | maxItems | Not yet | Not yet | | minItems | Not yet | Not yet | | uniqueItems | Not yet | Not yet |