TypeError: Cannot read property 'sessions' of undefined

Question

I am writing tests and I do not know js well, but I need to find the answer quickly. In the courses, I have not reached this point yet, or maybe I just don’t understand. Please help me figure out what I'm doing wrong.

I have two questions:

• The test starts working as soon as I delete the line:

  .then((response) => {
     authId = response.body.result.sessions[0].authId;
  });
  

if you do not delete this line, an error appears: TypeError: Cannot read property 'sessions' of undefined

• How to write so that the fields are optional, that is, you can pass, or you can not pass

(props: { authId: string; deviceId: string })

This is the response.body I am trying to parse:

{
  "result": {
    "sessions": [
      {
        "type": "web",
        "authId": "jRXtO7oNiBR5Ldeq",
        "platform": "platform",
        "application": "application",
        "seenAt": 1592052380
      }
    ],
    "integrations": []
  },
  "success": true
}

My code:

import { agent } from 'supertest';
import { config } from '../../config';
import { getSsoId } from '../../helpers/getUserFromGenesis';

describe('First', () => {
    let id;
    let authId;

    beforeEach(async () => {
        id = await getId();
    });

    const userAuthorizations = (fn: (response: any) => void) =>
        agent(config.baseUrl)
            .get(`users/${id}/authorizations?client_id=test`)
            .auth(config.user, config.pass)
            .expect((response) => {
                fn(response);
            });

    const deleteUserAuthorizations = (props: { authId: string; deviceId: string }) =>
        agent(config.baseUrl)
            .delete(`users/authorizations`)
            .auth(config.user, config.pass)
            .send(props)
            .expect((response) => {
                expect(response.body.result.success).toEqual(true);
            });

    const getSession = () =>
        agent(config.tokenQaUrl)
            .post(`/token`)
            .auth(config.user, config.pass)
            .send({
                clientId: 'test',
                userId: id,
            })
            .expect((response) => {
                expect(response.body.sessionId).not.toEqual('');
                expect(response.body.sessionId).not.toEqual(null);
            })
            .then((response) => {
                authId = response.body.result.sessions[0].authId;
            });

    it('test', async () => {
        await getSession().then(() =>
            userAuthorizations((response) => {
                expect(response.body.result.sessions.length).toBeGreaterThan(0);
            }),
        );
    });
});

Answer 1

I am a bit unclear on your question. There are some good answers up top.

In case you are trying to avoid a "property of undefined error" you can do something like this:

authId = response?.body?.result?.sessions[0]?.authId;

it prevents the error. Ideally you would type-check all of them.

Answer 2

As discussed in the comment

1. It seems like some time your response is getting the JSON data in the way which you are trying to access, but some time its not. Its better to add conditions before trying to access data where the JSON is not of fixed structure.

2. To make these property optional just add ? it will make the properties option props: { authId?: string; deviceId?: string }