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Fusioncat is currently in its alpha stage. The main API server is located at: https://api.staging.fusioncatalyst.io/Please note that breaking changes and bugs are to be expected, as the product is still under active development.

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Code Generation Commands

The paw codegen commands allow you to generate code in multiple programming languages from your FusionCatalyst project definitions.

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Commands

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codegen app

Generate code for a specific application. 
paw codegen app --app-id <id> [--language <language>]

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Options

Currently only Golang codegeneration is properly implemented and tested.
  • --app-id (required): The ID of the application to generate code for
  • --language: Target programming language (overrides settings file)
    • typescript
    • python
    • java
    • go

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Examples

# Generate using default language from settings
paw codegen app --app-id "app-uuid"

# Generate TypeScript code
paw codegen app --app-id "app-uuid" --language typescript

# Generate Python code
paw codegen app --app-id "app-uuid" --language python

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Supported Languages

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TypeScript

  • Use cases: Node.js backends, React/Angular/Vue frontends
  • Features: Full type safety, interfaces, async/await
  • Output: TypeScript definitions and helper functions

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Python

  • Use cases: Django/FastAPI backends, data processing
  • Features: Type hints, dataclasses, async support
  • Output: Python classes and type definitions

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Java

  • Use cases: Spring Boot, enterprise applications
  • Features: POJOs, builders, validation annotations
  • Output: Java classes with getters/setters

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Go

  • Use cases: Microservices, high-performance backends
  • Features: Structs, interfaces, channels
  • Output: Go structs and interfaces

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Generated Code Structure

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TypeScript Example

For a User schema: 
// Generated types
export interface User {
  id: string;
  email: string;
  name: string;
  createdAt: string;
}

// Generated validators
export function validateUser(data: unknown): User {
  // Validation logic
}

// Generated API client
export class UserAPI {
  async getUser(id: string): Promise<User> {
    // API call implementation
  }
}

// Generated message handlers
export const userEvents = {
  UserCreated: {
    publish: async (event: UserCreatedEvent) => {
      // Publish logic
    },
    subscribe: async (handler: (event: UserCreatedEvent) => Promise<void>) => {
      // Subscribe logic
    }
  }
};

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Python Example

# Generated types
from dataclasses import dataclass
from typing import Optional
from datetime import datetime

@dataclass
class User:
    id: str
    email: str
    name: str
    created_at: datetime

# Generated validators
def validate_user(data: dict) -> User:
    # Validation logic
    pass

# Generated API client
class UserAPI:
    async def get_user(self, id: str) -> User:
        # API call implementation
        pass

# Generated message handlers
class UserEvents:
    @staticmethod
    async def publish_user_created(event: UserCreatedEvent):
        # Publish logic
        pass

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Configuration

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Language Settings

Set default language in settings file: 
paw init-settings-file --language typescript
Or in fcsettings.json: 
syntax_version: 1
server: https://api.fusioncat.dev
code_generation:
    output_folder: generated
    language: go
    class_suffix: FCModel

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Output Directory

Generated code is placed in:
  • ./fusioncant/ - Default output directory
generated/
├── c04beaff-870e-44ba-8dce-793715459e9f.go

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Code Generation Workflow

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1. Initial Generation

# Create project and schemas
paw projects new --name "My API" --belongs-to user
paw schemas new --project-id "proj-id" --name "User" --type jsonschema --schema-file user.json

# Create app
paw apps new --project-id "proj-id" --name "Backend API"

# Generate initial code
paw codegen app --app-id "app-id" --language typescript

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2. Development

  1. Generated code provides the foundation
  2. Add business logic on top
  3. Don’t modify generated files directly

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3. Schema Updates

# Update schema
paw schemas update --schema-id "schema-id" --schema-file user-v2.json

# Regenerate code
paw codegen app --app-id "app-id"

# Generated code now includes new fields

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Integration Patterns

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Separate Generated Code

Keep generated code separate from business logic: 
// generated/types/user.ts (DO NOT EDIT)
export interface User {
  id: string;
  email: string;
  name: string;
}

// src/services/user.service.ts (Your code)
import { User } from '../generated/types/user';

export class UserService {
  async createUser(data: Omit<User, 'id'>): Promise<User> {
    // Your business logic
  }
}

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Extend Generated Classes

# generated/models/user.py (DO NOT EDIT)
@dataclass
class User:
    id: str
    email: str
    name: str

# src/models/user_extended.py (Your code)
from generated.models.user import User

class ExtendedUser(User):
    def get_display_name(self) -> str:
        return f"{self.name} ({self.email})"

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Best Practices

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Version Control

  1. Commit generated code: Include in version control
  2. Mark as generated: Add headers indicating files are generated
  3. Regenerate in CI: Ensure consistency

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Continuous Generation

# In your build script
#!/bin/bash
echo "Regenerating code..."
paw codegen app --app-id "$APP_ID"

echo "Running tests..."
npm test

echo "Building application..."
npm run build

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Multiple Apps

Generate different code for different apps: 
# Frontend app - TypeScript
paw codegen app --app-id "frontend-id" --language typescript

# Backend app - Python
paw codegen app --app-id "backend-id" --language python

# Mobile app - TypeScript (React Native)
paw codegen app --app-id "mobile-id" --language typescript

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Examples

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Full Stack Application

# Create schemas
paw schemas new --project-id "proj" --name "User" --type jsonschema --schema-file schemas/user.json
paw schemas new --project-id "proj" --name "Product" --type jsonschema --schema-file schemas/product.json

# Create apps
paw apps new --project-id "proj" --name "React Frontend"
paw apps new --project-id "proj" --name "Node.js Backend"

# Generate TypeScript for both
paw codegen app --app-id "frontend-id" --language typescript
paw codegen app --app-id "backend-id" --language typescript

# Frontend uses generated types
# Backend uses generated types + API handlers

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Microservices

# Different languages for different services
paw codegen app --app-id "user-service" --language go
paw codegen app --app-id "order-service" --language java
paw codegen app --app-id "notification-service" --language python
paw codegen app --app-id "analytics-service" --language typescript

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Event-Driven System

# Generate event handlers
paw codegen app --app-id "event-producer" --language python
paw codegen app --app-id "event-consumer" --language typescript

# Generated code includes:
# - Event type definitions
# - Serialization/deserialization
# - Publisher/subscriber interfaces
# - Topic/queue configurations

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Troubleshooting

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Missing Dependencies

Generated code may require additional packages: 
# TypeScript
npm install ajv uuid

# Python
pip install pydantic python-dateutil

# Java
# Add to pom.xml or build.gradle

# Go
go get github.com/go-playground/validator/v10

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Schema Compatibility

When updating schemas:
  1. Consider backward compatibility
  2. Use schema versioning
  3. Update dependent apps gradually

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Code Conflicts

If regeneration causes conflicts:
  1. Review schema changes
  2. Check for breaking changes
  3. Update business logic accordingly
  • Apps - Create applications to generate code for
  • Schemas - Define schemas for code generation
  • Projects - Manage projects containing apps