JSON Schema Transpiler (eth-json-schema-transpiler)

0.0.0-development verified Fri May 01 auth: no javascript

A dev tool that converts JSON Schemas into type definitions for multiple languages including TypeScript, Go, Rust, and Python. Version 0.0.0-development is in early development with limited updates. It features automatic cycle detection, reference resolution, and deterministic title generation. Key differentiators: minimal dependencies, synchronous execution, and browser support via the web demo. The package generates one type alias per schema and includes documentation annotations.

Common errors

error TypeError: JsonSchemaTranspiler is not a constructor ↓

cause Importing as named export instead of default, or using CommonJS without .default

fix

Use import JsonSchemaTranspiler from 'eth-json-schema-transpiler' (ESM) or const JsonSchemaTranspiler = require('eth-json-schema-transpiler').default (CJS)

error Error: Invalid schema: schema must be an object ↓

cause Passing a JSON string instead of a parsed object to the constructor

fix

Parse the JSON string first: JSON.parse(schemaString)

error TypeError: transpiler.to is not a function ↓

cause Using an outdated version that does not have the .to() method, or importing incorrectly

fix

Update to latest version. If using CommonJS, ensure you used .default.

error Error: Unsupported language 'python3' ↓

cause Providing an unsupported language name to .to()

fix

Use one of: 'typescript', 'go', 'rust', 'python'

Warnings

breaking Upgrading from v0.0.1 to v0.0.2 changes default output format for Go and Rust outputs. TypeScript output now includes optional properties. ↓

fix Review generated types and adjust downstream code if needed.

deprecated The .to('language') shorthand is deprecated in favor of explicit language methods (toTypescript, toGo, toRust, toPython). ↓

fix Use toTypescript() instead of to('typescript').

gotcha JSON Schema $ref references may not be resolved in browser environments without bundler configuration for json-schema-ref-parser. ↓

fix Ensure your bundler (e.g., webpack) includes Node.js polyfills for path and url modules.

gotcha The package is case-sensitive about language names: 'typescript', 'go', 'rust', 'python' are supported. 'TypeScript' or 'py' will throw an error. ↓

fix Use exact lowercase names when calling .to(), or use the dedicated methods.

Install

npm install eth-json-schema-transpiler

yarn add eth-json-schema-transpiler

pnpm add eth-json-schema-transpiler

Imports

default

wrong

import { JsonSchemaTranspiler } from 'eth-json-schema-transpiler'

correct

import JsonSchemaTranspiler from 'eth-json-schema-transpiler'

The package exports a default class, not named exports. CommonJS users should use require().default.

JsonSchemaTranspiler
wrong
```
const JsonSchemaTranspiler = require('eth-json-schema-transpiler')
```
correct
```
import JsonSchemaTranspiler from 'eth-json-schema-transpiler'
```
CommonJS require returns the module, so you need .default: const JsonSchemaTranspiler = require('eth-json-schema-transpiler').default

toTypescript

wrong

JsonSchemaTranspiler.toTypescript(schema)

correct

const transpiler = new JsonSchemaTranspiler(schema); transpiler.toTypescript()

toTypescript is an instance method, not static.

Quickstart

Shows basic usage: import default, instantiate with schema, call toTypescript method.

import JsonSchemaTranspiler from 'eth-json-schema-transpiler';

const mySchema = {
  title: 'Person',
  type: 'object',
  properties: {
    name: { type: 'string' },
    age: { type: 'integer' }
  },
  required: ['name']
};

const transpiler = new JsonSchemaTranspiler(mySchema);

console.log(transpiler.toTypescript());
// Output: type Person = { name: string; age?: number; };