Unhandled Promise rejection typescript and Node.js

Question

Good night to you all! I am developing an app with React, Node and typescript and was programming a route with post method for inserting data using sqlite database and testing in India but when running the file it returns me an error of Unhandled Promise rejection and I do not know how to treat this event.

this and my route:

routes.post('/points', async(request, response)=>{

    const {
        name,
        email,
        whatsapp,
        latitude,
        longitude,
        city,
        uf,
        items
    }=request.body;


   await knex('points').insert({
        image: 'image_fake',
        name,
        email,
        whatsapp,
        latitude,
        longitude,
        city,
        uf,

    })
    return response.json({sucess: true});

});

in India I make a request of the post type and the json body as follows

{
    "name": "Mercado Livre",
    "email": "[email protected]",
    "whatsapp": "3198774664",
    "latitude": "-45.4892729",
    "longitude": "-35.4324233",
    "city": "BH",
    "uf": "MG",
    "items": [
        1,
        2,
        6
    ]
}

the expected was for me to have an "sucess: true;" response according to my Return Response.json({sucess: true});

but he returns me the following:

(Ode:13488) Unhandledpromiserejectionwarning: Error: Insert into points (city, email, image, latitude, longitude, name, uf, whatsapp) values ('BH', '[email protected]', 'image_fake', '-45.4892729', '-35.4324233', 'Mercado Livre', 'MG', '3198774664') - SQLITE_ERROR: table points has no column named Whatsapp (Ode:13488) Unhandledpromiserejectionwarning: Unhandled Promise rejection. This error either originated by Throwing Inside of an async Function without a catch block, or by rejecting a Promise which was not handled with . (catch). To terminate the Node process on unhandled Promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2) (Ode:13488) [DEP0018] Deprecationwarning: Unhandled Promise rejections are deprecated. In the Future, Promise rejections that are not handled will terminate the Node.js process with a non-zero Exit code.

could someone help me?

Answer 1

Express does not have a method for capturing bounces of promises natively. Therefore, how are you using async/await, should always ensure that no rejected promise "get out" from inside the router, since there is no other mechanism to treat it.

You can use blocks try/catch:

routes.post('/points', async (request, response) => {
  try {
    const {
      name,
      email,
      // ...
    } = request.body;

    await knex('points').insert({
      name,
      email,
      // ...
    });

    return response.json({ sucess: true });
  } catch (error) {
    response.json({
      error: true,
      message: error.message
    }); 
  }
});

In your specific case, the error is in trying to insert a disgusting record in points. According to the error message, there is no column whatsapp on the table:

SQLITE_ERROR: table points has no column named whatsapp

There are other ways to solve this problem, such as using some higher order function (Higher order Function), which will make a more generic error handling, or chain the catch directly in the method that returns to Promise.

To learn more about the warning unhandledPromiseRejection, read this answer.

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I also put a semicolon at the end of a missing line. It may seem "freshness", but this avoids some bizarre situations that can occur if you don’t use them (see more about this here).