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Manolait
Asked: 2020-05-24 22:41:30 +0800 CST 2020-05-24 22:41:30 +0800 CST

Async and await return the catch of the function that I call and not of the main one

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I am using async and await for the first time, the promises with then if I have used them more, but when using async await I have some doubts when managing the catch.

First of all, I have a main function (FuncionLanzar) that is in charge of calling the rest of the functions that launch a series of requests to an API and process the data.

It has to be a sequential process since I retrieve token, send it to second etc.

This is my main function:

const FuncionLanzar = async() => {
    try {
        const resp = await postToken()
        var access_token = resp.data.access_token;
        var token = 'Bearer ' + access_token;
        const resp2 = await getStations(token)
        var datos = resp2.data;
        for (let j = 0; j < datos.length; j++) {
            const id_stacions = datos[j].id_station;
            const FiwareService = datos[j].Fiware_Service;
            const FiwareServicePath = datos[j].Fiware_ServicePath;
            const lastdata = await getLastData(token, id_stacions)
            var json = lastdata.data.data;
            const Jformat_fiware = await FormatFiware(json)
            const envio = await PostFiware(Jformat_fiware, id_stacions, FiwareService, FiwareServicePath);
            console.log("Envio correcto de los datos");
        }
    } catch (error) {
        console.error('Error en el enviooooooooooo' + error)
        transporter.sendMail(mailOptions, function(error, info) {
            if (error) {
                console.log(error);
            } else {
                console.log('Email enviado: ' + info.response);
            }
        });
    }
}

The problem is that it never leads this catch to send a mail when it encounters an error or even if I put a console.log to show the error information. Since in the functions that I call it used axios to make the requests, it also has try async await and when it fails it returns that catch and not the one from the main function.

Function example:

const getStations = async(token) => {
    var config = {
        headers: { "accept": "application/json", "Authorization": token },
    };
    try {
        return await axios.get(`xxxxxxxxxxxxxxxx`, config)
    } catch (error) {
        console.error(error)
    }
}

I do not want to put the sending of mail in each catch of the functions that are called (getStations), the most logical thing is that the catch of the main function (FuncionLanzar) handles the errors in its catch, but I understand that when finding an error in the function called (getStations) from that error and terminates the process.

How could I do this? removing the try and catch from the functions it called and leaving just the one from the main function?

I don't know if I'm very clear.

Edit01

Hello again, I have tried to eliminate all the try and catch of the functions that are called and in this way if it uses the catch of my main function, I don't know if it is the correct way, but for now it works.

All the best.

javascript

1 Answers

  1. Best Answer

    Based on the code you posted, I'll explain what you're doing wrong.

    Let's say we have the main function that calls the others.

    const FuncionLanzar = async() => {
    try {
        const resp = await postToken()
        var access_token = resp.data.access_token;
        var token = 'Bearer ' + access_token;
        const resp2 = await getStations(token)
        var datos = resp2.data;
        for (let j = 0; j < datos.length; j++) {
            ...
            const lastdata = await getStations(token, id_stacions) // getStations como ejemplo
            ....
        }
    } catch (error) {
        console.error('Error en el enviooooooooooo' + error)
        transporter.sendMail(mailOptions, function(error, info) {
            if (error) {
                console.log(error);
            } else {
                console.log('Email enviado: ' + info.response);
            }
        });
    }
}

    Now let's see what the getStations function does.

    As you can see, all the code is wrapped in a try catch, so here we have two possibilities

    1. Handle the error in the same function (getStations)
    2. Pass the exception up.

    const getStations = async(token) => {
  var config = {
      headers: { "accept": "application/json", "Authorization": token },
  };
  try {
      return await axios.get(`xxxxxxxxxxxxxxxx`, config)
  } catch (error) {
      //Fijate que aqui no levantas la exepcion, y por eso en el metodo 
      //padre no ocurre nada, ya que da por entendido que la exepcion se 
      //proceso correctamente.
      console.error(error)

      //En tu caso harias esto para pasar la exepcion al padre.
      throw error
  }
}

    In your case what interests you is that in the function FunctionLanzaryou can process all the exceptions that may occur.

    I leave you another example that I hope will help you more to understand it.

    function send(){
  algun_func() // No existe: ReferenceError exception
}


function main(){
  try {
    //Llamamos a una funcion, que produce un error
    send()
  }catch(err){
    //Recogemos cualquier error
    console.log(err)
   //Aquí es donde enviarias el correo.
  }
}

main()

    I leave you the documentation that explains everything very well.

    I hope it helps you and that I explained myself well.

    Cheers!!!

    • 1