Denvmon

Denvmon is a powerful utility for parsing environment variables using a class model structure. It leverages TypeScript decorators to define and validate environment variables based on their types.

Features

• Support for environment variables of type STRING, NUMBER, and BOOLEAN.
• Configurable properties such as defaultValue, required, and validation rules like min, max, or allowed values.
• Uses TypeScript decorators for clean and declarative configuration.

Installation

Install the package using npm or yarn:

npm install denvmon

tsconfig.json

{
    "compilerOptions": {
      "experimentalDecorators": true,
    },
}

Usage

Step 1: Define Your .env File

Create a .env file in the root of your project with the following contents:

TIMEOUT=3000
IS_PRODUCTION=false
APP_NAME=MyApp
DATABASE_URI=test
DURATION=4.5

Step 2: Import the Required Modules

import { Denvmon, IsString, IsNumber, IsBoolean } from "denvmon";

Step 3: Define Your Class Model

Define your environment variables using the provided decorators:

import { Denvmon, IsBoolean, IsNumber, IsString } from "denvmon";

@Denvmon()
class Config {
  @IsString("DATABASE_URI")
  DATABASE_URI!: string;

  @IsNumber("TIMEOUT", {
    isInt: true,
  })
  timeout!: number;

  @IsNumber("TIMEOUT")
  sleep!: number;

  @IsBoolean("IS_PRODUCTION")
  is_production!: boolean;

  @IsNumber("DURATION")
  duration!: number;

  @IsBoolean("CUSTOM_BOOLEAN", {
    types: ["yes", "no"],
  })
  custom_boolean!: boolean;
}

const config = new Config();
console.log(config);

Example Output

When you run the above code with the .env file provided, you will get the following output:

{
  DATABASE_URI: "test",
  timeout: 3000,
  sleep: 3000,
  is_production: false,
  duration: 4.5,
  custom_boolean: false
}

API Reference

@IsString

Defines a string environment variable.

@IsString(key: string, {
  defaultValue?: string;
  required?: boolean;
  max?: number;
  min?: number;
})

• key: The name of the environment variable.
• defaultValue: The default value if the variable is not set.
• required: Whether the variable is required (default: true).
• max: Maximum string length.
• min: Minimum string length.

@IsNumber

Defines a number environment variable.

@IsNumber(key: string, {
  defaultValue?: number;
  required?: boolean;
  isInt?: boolean;
})

• key: The name of the environment variable.
• defaultValue: The default value if the variable is not set. Supports integers and floats.
• required: Whether the variable is required (default: true).
• isInt: Whether the number must be an integer.

@IsBoolean

Defines a boolean environment variable.

@IsBoolean(key: string, {
  defaultValue?: boolean;
  required?: boolean;
  types?: [string, string];
})

• key: The name of the environment variable.
• defaultValue: The default value if the variable is not set.
• required: Whether the variable is required (default: true).
• types: The string representation of true and false values.

Custom Boolean Types Example

You can define custom string representations for boolean values using the types option:

@IsBoolean("CUSTOM_BOOLEAN", {
  types: ["yes", "no"],
})
custom_boolean!: boolean;

In the .env file, you can use:

CUSTOM_BOOLEAN=yes

The custom_boolean property in the class will then be set to true if the value is "yes" or false if the value is "no".