Environment validator

The environment validator provider is used to validate the existence of the .env file and its content. It helps the developer to avoid runtime errors caused by missing environment variables.

Setup

To use the environment validator provider, you need to make sure it is registered in the configureServices() method of the App class. Once registered, the provider will be available in the application through the DI Container.

    protected configureServices(): void | Promise<void> {
        this.provider.register(Env);
    }

Method checkAll

The checkFile() method is used to validate the existence of the .env file and its content by checking if all the environment variables are defined.

You can define from where to call the checkAll() method. It can be called in the postServerInitialization() method or in any other method that you prefer.

    protected postServerInitialization(): void | Promise<void> {
        if (this.isDevelopment()) {
            this.Provider.get(Env).checkFile(".env.development");
        }
    }

If the .env file is missing or if any environment variable is not defined, the checkFile() method will throw an error with a message indicating the missing environment variables.

PORT environment variable is missing

[PID:26759] ERROR [env-validator-provider] Environment variable PORT is not defined.

Method get

The environment validator provider also has a method called get() that returns the value of an environment variable. It is used to get a specific environment variable value passing its name as a parameter.

this.Provider.get(Env).get("PORT");

Using everywhere

You can use the Env provider in any class by injecting it into the constructor of your usecase, service, provider, controller or any other class.

import { Get, controller } from "@expressots/adapter-express";
import { Env } from "@expressots/core";

@controller("/")
export class AppController {
    constructor(@inject(Env) private env: Env) {}

    @Get("/")
    execute(): string {
        console.log(this.env.get("PORT"));
        return "Hello from Expressots!";
    }
}

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