techvlad / classenv

Describe your environment variables contract with TypeScript class

classenv

A perfect typescript class environment variables library.

• Strongly-typed declarative class containing your environment data
• Type-casting using TypeScript metadata reflection
• Auto UPPER_SNAKE_CASE conversion
• Throws runtime error if variable doesn't exist
• Default values support
• Makes decorated properties read-only in runtime

.env

IS_SOMETHING_ENABLED=1

import { Env } from 'classenv';

class Environment {
  @Env() // Auto UPPER_SNAKE_CASE conversion supported
  static isSomethingEnabled: number;

  @Env() // Won't throw, because got default value
  static withDefault: string = 'yeah its me'

  @Env('IS_SOMETHING_ENABLED')
  static isEnabledStr: string;

  @Env('IS_SOMETHING_ENABLED')
  static isEnabledNmbr: number;

  @Env('IS_SOMETHING_ENABLED')
  static isEnabledBln: boolean;
}

 // string 1
console.log(typeof Environment.isEnabledStr, Environment.isEnabledStr)
 // number 1
console.log(typeof Environment.isEnabledNmbr, Environment.isEnabledNmbr)
 // boolean true
console.log(typeof Environment.isEnabledBln, Environment.isEnabledBln)
 // number 1
console.log(typeof Environment.isSomethingEnabled, Environment.isSomethingEnabled)

Environment.isEnabledBln = false;
// TypeError: Cannot assign to read only property 'isEnabledBln' of function 'class Test{}'

@Env property data type should be scalar (string, number or boolean).

Dependencies

reflect-metadata

npm i reflect-metadata

And then import it somewhere close to your entry point (index.ts/main.ts/etc...). Should be imported before any of your environment classes.

import 'reflect-metadata';

tsconfig.json

These settings should be enabled

"emitDecoratorMetadata": true,
"experimentalDecorators": true,