Typescript issue

Hello,

I am having an issue when trying to use the library with typescript in NestJS. I have the following code :

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import Mailjet, { SendEmailV3_1 } from 'node-mailjet';

@Injectable()
export class MailjetService {
  private mailjet: Mailjet;

  constructor(private readonly configService: ConfigService) {
    this.mailjet = new Mailjet({
      apiKey: this.configService.get('MJ_APIKEY_PUBLIC'),
      apiSecret: this.configService.get('MJ_APIKEY_PRIVATE'),
    });
  }

  async sendForgottenPasswordMail(token: string, recipientMail: string) {
    const data: SendEmailV3_1.IBody = {
      Messages: [
        {
          From: {
            Email: '[e-mail]',
            Name: 'SomeName',
          },
          To: [{ Email: recipientMail }],
          TemplateID: SOME_TEMPLATE_ID,
        },
      ],
    };

    const res = await this.mailjet
      .post('send', { version: 'v3.1' })
      .request<SendEmailV3_1.IResponse>(data);

    const { Status } = res.body.Messages[0];
  }
}

Typescript says :

Type 'IResponse' does not satisfy the constraint 'TRequestData'.
Type 'IResponse' is not assignable to type 'TUnknownRec'.
Index signature for type 'string' is missing in type 'IResponse'.ts(2344)

I can’t see any difference between my current code here and the documentation example, so any help is welcome. I think I’m probably missing something here.

package.json version : 5.1.1

Bests, Max

[woodinteractive]

I’m having an issue just trying to get it instantiated.

export class MailjetService {
	private _transporter: nodemailer.Transporter
	private mailjet: Mailjet
	constructor(private readonly configService: ConfigService) {
		this.mailjet = new Mailjet({
			apiKey: process.env.MJ_APIKEY_PUBLIC,
			apiSecret: process.env.MJ_APIKEY_PRIVATE
		})
...

Error output says: TypeError: node_mailjet_1.default is not a constructor

Am I missing something?

[Codesleuth]

I think that the following code is fundamentally flawed:

const result = await mailjet
  .post('send', { version: 'v3.1' })
  .request({ ...data });

// result is ILibraryResponse<TRequestData>

The type of result should not represent TRequestData - that’s a request shape, not a response shape. You actually want it to be ILibraryResponse<SendEmailV3_1.IResponse> but it isn’t compatible.

A workaround is to use a type predicate:

function isSendResponse(r: unknown): r is ILibraryResponse<SendEmailV3_1.IResponse> {
  if (r == null || typeof r !== 'object') return false;
  const o = r as { body?: { Messages: unknown } };
  return o.body?.Messages != null && Array.isArray(o.body.Messages);
}

const result = await mailjet
  .post('send', { version: 'v3.1' })
  .request({ ...data });

if (!isSendResponse(result)) {
  // probably never hit, but you just don't know
  throw new Error('Unexpected response body');
}

const { Status } = result.body.Messages[0];
// ...

Arguably, this is more reliable than if the type system worked today. At least in this code, there’s runtime checking of the response to give you some level of confidence that the API response is what you expect. Feel free to extend isSendResponse with further checks for what you need (maybe a json schema check?)