json2schema

Convert JSON into a JSON Schema (draft v4). Generates schema draft v4 from JSON data.

Installation

npm install gratex/json2schema

Or globally to use as CLI:

npm install -g gratex/json2schema

CLI Usage

cat input.json | json2schema [options]

Or run directly without installation:

cat input.json | node cli.js [options]

Options

All options can be passed as CLI arguments using --option=value or --option (for booleans, sets to true). Boolean options can also be set to false with --option=false, or using --option=1 (true) and --option=0 (false).

Option	Default	Description
--numberInteger	true	Treat numbers as integer if possible
--numberPositive	true	Numbers must be positive
--numberJsMinMax	true	Use JS min/max for numbers
--dateTimeNative	true	Use native Date type
--dateTimeIsoString	true	Use ISO string for Date
--namingConventions	false	Apply naming conventions
--allMandatory	true	All properties mandatory
-r		Shortcut for --allMandatory=false
-h, --help		Show help message

Examples

# Basic usage
echo '{"name": "John", "age": 30}' | json2schema

# Output to file
cat input.json | json2schema > schema.json

# Make properties optional
cat input.json | json2schema -r > schema.json

# Disable integer detection
cat input.json | json2schema --numberInteger=false > schema.json

Module Usage

const obj2schema = require('json2schema');

// Basic usage
const schema = obj2schema({ name: 'John', age: 30 });
console.log(JSON.stringify(schema, null, 2));
// Output:
// {
//   "type": "object",
//   "additionalProperties": false,
//   "properties": {
//     "name": { "type": "string", "required": true },
//     "age": { "type": "integer", "required": true }
//   }
// }

// With options
const schema = obj2schema({ items: [1, 2, 3] }, { allMandatory: false });
console.log(JSON.stringify(schema, null, 2));
// Output:
// {
//   "type": "object",
//   "additionalProperties": false,
//   "properties": {
//     "items": {
//       "type": "array",
//       "additionalItems": false,
//       "items": { "type": "integer" }
//     }
//   }
// }

Options

Option	Default	Description
numberInteger	true	Treat numbers as integer if possible
numberPositive	true	Numbers must be positive
numberJsMinMax	true	Use JS min/max for numbers
dateTimeNative	true	Use native Date type
dateTimeIsoString	true	Use ISO string for Date
namingConventions	false	Apply custom naming conventions
allMandatory	true	All properties are required
schemaHeader	true	Include JSON Schema header

Custom Naming Conventions

You can provide a custom function to infer types from property names:

const schema = obj2schema({
  userId: 1,
  userName: 'John'
}, {
  namingConventions: (value, key, schema) => {
    if (key.endsWith('Id')) {
      schema.type = 'integer';
    } else if (key.endsWith('Name')) {
      schema.type = 'string';
    }
  }
});

Development

# Install dependencies
npm install

# Run tests
npm test

License

MIT - Copyright (c)