The update route will update an existing contact with new details. We can achieve this by getting the required id as a route parameter, along with the updated content from the request body, then using the mongoose .findByIdAndUpdate() method to update the specified contact. The route will return the updated contact as a response on a successful update:

// ./controllers/ContactController.js

// ...

module.exports = {
  async index(ctx) {
    const contacts = await Contact.find();
    ctx.body = {
      status: 'success',
      data: contacts
    };
  },

  async store(ctx) {
    const { body } = ctx.request;
    let contact = new Contact(body);
    contact = await contact.save();
    ctx.body = {
      status: 'success',
      data: contact
    };
  },

  async show(ctx) {
    const { id } = ctx.params;
    const contact = await Contact.findById(id);
    ctx.body = {
      status: 'success',
      data: contact
    };
  },
 
  async update(ctx) {
    const { id } = ctx.params;
    const { body } = ctx.request;
    await Contact.findByIdAndUpdate(id, body);
    const contact = await Contact.findById(id);
    ctx.body = {
      status: 'success',
      message: 'contact successfully updated',
      data: contact
    };
  }
};

The corresponding router definition is shown as follows:

// ./middleware/router.js
// ...

router
  .get('/', async ctx => (ctx.body = 'Welcome to the contacts API!'))
  .get('/contact', contactController.index)
  .post('/contact', contactController.store)
  .get('/contact/:id', contactController.show)
  .put('/contact/:id', contactController.update);

// ...

An example request to PUT /contact/{contactId} to update a contact is shown in the following screenshot: