NestPack Mail

A Mail Module for NestJs that allows for swappable Email Services.

Installation

$ npm install @nestpack/mail
# OR
$ yarn add @nestpack/mail

Usage

Import the MailModule and register on your root AppModule.

// app.module.ts
import { Module } from '@nestjs/common';
import { MailModule } from '@nestpack/mail';
import { AppController } from './app.controller';

@Module({
  imports: [MailModule.forRoot()],
  controllers: [AppController]
})
export class AppModule {}

Drivers are used to switch between email providers. By default, MemoryMailDriver is used. This driver does not send emails to a 3rd party provider, and, instead, holds your emails in memory.

To use a different driver, register it by passing it into the driver option.

forRoot() will import the MailModule globally, meaning you don't need to import everywhere, and everything shares the same configuration. forFeature() can also be used to use different configurations in different modules.

In this example, MemoryMailDriver is used, but a different 3rd party driver would be passed in. (If nothing is passed in MemoryMailDriver is used anyway.)

// app.module.ts
import { Module } from '@nestjs/common';
import { MailModule, MemoryMailDriver } from '@nestpack/mail';
import { AppController } from './app.controller';

@Module({
  imports: [MailModule.forRoot({
    driver: MemoryMailDriver
  })],
  controllers: [AppController]
})
export class AppModule {}

Next, create something that can be emailed by creating a new Mailable. This can be a class instance, or an object so long as it implements the IMailable interface.

// confirmation.mailable.ts
import { IMailable } from '@nestpack/mail';
import { User } from 'user/user.entity.ts';

export class ConfirmationMailable implements IMailable {
  constructor(public user: User){
    this.to = [user.email];
    this.from = '[e-mail]'
    this.text = 'Hello world';
  }
}

Now that the mailable is created, inject the MailService somewhere in the app, and send the email.

import { Injectable } from '@nestjs/common';
import { MailService } from '@nestpack/mail';
import { User } from '../user/user.entity.ts';
import { ConfirmationMailable } from '../confirmation.mailable.ts'


@Injectable()
export class YourService {
  constructor(private readonly mailService: MailService){}

  async sendConfirmationEmail(user: User){
    await this.mailService.sendMail(new ConfirmationMailable(user));

  }
}

Usage with testing

By default, when NODE_ENV is test the MemoryMailDriver will be used. This means that within tests, emails aren't sent to the 3rd party services. In order to get test emails, the MemoryMailDriver needs to be accessed directly from the module system as show below.

    const module = await Test.createTestingModule({
      imports: [
        MailModule.forRoot(),
      ],
    }).compile();

    const mailService = module.get(MailService);
    const mailDriver = module.get(MemoryMailDriver);


    // Email is not sent, and is stored in-memory instead.
    await service.sendMail({ to: ['[e-mail]'] });

    expect(mailDriver.getTestEmails()).toMatchObject([{ to: ['[e-mail]'] }]);

    mailDriver.resetTestEmails();

    expect(mailDriver.getTestEmails()).toMatchObject([]);

Writing a Driver

A custom Mail Driver must be a class that implements the IMailDriver interface. The driver is dependency injected, so the class has access to the Nest module system, including the options passed into MailModule.forRoot().

import { Inject, Injectable } from '@nestjs/common';
import { IMailable, IMailDriver, IMailModuleOptions } from '@nestpack/mail';

@Injectable()
export class CustomMailDriver implements IMailDriver {
  constructor(@Inject('MAIL_OPTIONS') private options: IMailModuleOptions) {}

  async sendMail(mailable: IMailable) {
    // Global 3rd party mailer options.
    this.options.driverOptions;

    // Mailable specific 3rd party mailer options.
    mailable.options;

    // Use the options above to set up your custom driver and send an email here.
  }
}