🌱 april-gen

april-gen is a powerful NestJS module developed by the team at April Innovations. It enables developers to dynamically generate fully functional CRUD modules at runtime via both a user interface and API routes.

Perfect for rapidly scaffolding resources in large-scale NestJS applications, april-gen significantly reduces development time and helps maintain consistency across your codebase.

✨ Features

✅ Auto-generate CRUD modules in seconds

🧠 Smart creation of:

• Controller

• Service

• Module

• DTOs

• Schema

• Swagger API Docs

🧩 Dynamic Form UI at /generate/form

⚙️ Seamless integration into NestJS projects

📄 Auto-generates .http files for API testing

📦 Installation

npm install april-gen

Note: Your project must have the following peer dependencies installed:

@nestjs/common

@nestjs/core

@nestjs/platform-express.

⚙️ Setup Instructions

1. Modify main.ts

  import { NestFactory } from '@nestjs/core';
  import { NestExpressApplication } from '@nestjs/platform-express';
  import { ValidationPipe } from '@nestjs/common';
  import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
  import { join, dirname } from 'path';
  import { registerAppPort } from 'april-gen';
  import { AppModule } from './app.module';}


  async function bootstrap() {
    const app = await NestFactory.create<NestExpressApplication>(AppModule);

    const PORT = 3001; // (Your port number)
    registerAppPort(PORT);    // Register port for internal routing
    const libPath = dirname(require.resolve('april-gen/package.json'));
    const viewsPath = join(libPath, 'dist', 'generateController', 'views');
    app.setBaseViewsDir(viewsPath);
    app.setViewEngine('hbs');

    app.useGlobalPipes(
      new ValidationPipe({
        whitelist: true,
        transform: true,
        transformOptions: { enableImplicitConversion: true },
        forbidNonWhitelisted: true,
      }),
    );

    const config = new DocumentBuilder()
      .setTitle('NestJS API Document')
      .setDescription('Use the base API URL as http://localhost:{PORT}')
      .setTermsOfService(`http://localhost:${PORT}/terms-of-service`)
      .setLicense('MIT License', '')
      .build();
    const document = SwaggerModule.createDocument(app, config);
    SwaggerModule.setup('api', app, document);

    await app.listen(PORT);
  }
  bootstrap();

2. Modify app.module.ts

import { Module } from '@nestjs/common';
import { GenerateModule } from 'april-gen';
@Module({
  imports: [GenerateModule],
})
export class AppModule {}

📬 Usage

UI Form (No Code Required)

Visit:

GET http://localhost:{PORT}/generate/form

You’ll see a UI to input the module name and fields, and generate code instantly.

🔸 API Route

Send a POST request to generate a new CRUD module dynamically.

POST http://localhost:{PORT}/generate

Request Body

{
  "entityName": "productData",
  "fields": [
    {
      "name": "fullName",
      "type": "String",
      "required": true,
      "description": "Product name",
      "example": "Tata Nexon",
      "enumValues": ["Tata Nexon"]
    },
    {
      "name": "price",
      "type": "Number",
      "required": true,
      "description": "Price of the product",
      "example": 1500000
    },
    {
      "name": "testObject",
      "type": "Object",
      "required": false,
      "description": "Testing object",
      "example": {}
    },
    {
      "name": "isActive",
      "type": "Boolean",
      "required": false,
      "default": true,
      "description": "Product active status",
      "example": true
    },
    {
      "name": "createdAt",
      "type": "Date",
      "required": false,
      "default": "new Date()",
      "description": "Product creation date",
      "example": "2024-01-01T00:00:00.000Z"
    },
    {
      "name": "images",
      "type": "Array",
      "arrayType": "String",
      "required": true,
      "description": "List of product image URLs",
      "example": ["image url 1", "image url 2"]
    },
    {
      "name": "serviceCenter",
      "type": "Array",
      "arrayType": "ServiceCenter",
      "required": false,
      "description": "List of associated service centers",
      "example": [
        {
          "name": "Prabhat Tata center",
          "location": "Thane",
          "area": "Mumbai"
        }
      ],
      "innerFields": [
        {
          "name": "name",
          "type": "String",
          "required": true,
          "description": "Name of the service center",
          "example": "XYZ Tata center"
        },
        {
          "name": "location",
          "type": "String",
          "required": true,
          "description": "Location (city/town)",
          "example": "Thane"
        },
        {
          "name": "area",
          "type": "String",
          "required": true,
          "description": "Area (region/district)",
          "example": "Mumbai"
        }
      ]
    },
    {
      "name": "specifications",
      "type": "Object",
      "objectType": "specifications",
      "required": false,
      "description": "Detailed product specifications",
      "example": {
        "engineType": "Petrol Engine",
        "isSuv": true,
        "groundClearance": 155
      },
      "innerFields": [
        {
          "name": "engineType",
          "type": "String",
          "required": true,
          "description": "Type of engine",
          "example": "Petrol Engine"
        },
        {
          "name": "isSuv",
          "type": "Boolean",
          "required": false,
          "description": "Is the vehicle an SUV?",
          "example": true
        },
        {
          "name": "groundClearance",
          "type": "Number",
          "required": false,
          "description": "Ground clearance in mm",
          "example": 155
        }
      ]
    }
  ]
}

This will generate a fully structured module named post with all the necessary files.

🗂️ Output Structure (Example)

src/
└── post/
    ├── dtos/
    │   └── post.dto.ts
    ├── http/
    │   ├── post.create.http
    │   ├── post.delete.http
    │   ├── post.fetchById.http
    │   ├── post.getAll.http
    │   ├── post.getAllByUserId.http
    │   ├── post.update.http
    │   └── post.updateByUser.http
    │   └── post.search.http
    ├── post.controller.ts
    ├── post.module.ts
    ├── post.schema.ts
    └── post.service.ts

🔍 Search API Guide

Route - POST //search

This API endpoint allows powerful querying using flexible filters, pagination, sorting, and lookup (join) operations.

📥 Example Body

In the below example, we are filtering the state collection where:

• The state name equals Maharashtra
• The state is related to the countries collection via countryId

{
  "filters": [
    {
      "field": "name",
      "operator": "eq",
      "value": "Maharashtra",
      "type": "string"
    },
    {
      "field": "countryId",
      "operator": "in",
      "value": [],
      "type": "objectId",
      "innerFilter": {
        "modelName": "countries",
        "projection": ["name"]
      }
    }
  ],
  "page": 1,
  "limit": 10,
  "sort": {
    "createdAt": "desc"
  },
  "projection": ["name"]
}

🧩 Filter Object Structure

Use this to define your search conditions. Each filter object contains the following keys:

| Key          | Type              | Description                                                                 |
|---------------|-------------------|-----------------------------------------------------------------------------|
| `field`       | `string`          | The field name in the model you want to filter.                            |
| `operator`    | `string`          | The condition to apply (`eq`, `regex`, `in`, `lt`, `lte`,`gt`,`gte`, etc.).               |
| `value`       | `any`             | The value(s) to match against.                                             |
| `type`        | `string`          | The data type of the field (`string`, `objectId`, `number`, etc.).         |
| `innerFilter` | `object` _(optional)_ | Used for lookups (joins). Contains `modelName` and `projection`.      |

📤 Example Response

[
  {
    "_id": "6836f135c86a2cfd6b87f9f8",
    "name": "Maharashtra",
    "countryId_lookup": {
      "name": "India"
    }
  }
]

To check swagger documentation

GET http://localhost:{PORT}/api#/

📝 License

MIT © 2025

👨‍💻 Developer:

Website: https://aprilinnovations.com/

Email: [email protected]

Name: Avinash Shirale

Demo

Watch the demo on YouTube