The Hapi handler function is failing to return a result

Question

The Hapi handler function is failing to return a result

I am encountering an issue while attempting to connect hapi.js with mysql. Specifically, when defining a server route, the handler is failing to return a value.

    server.route({
    method:'GET',
    path:'/hello',
    handler:function(request,h) {

        connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
            if (error) throw error;

            console.log('The solution is: ', results[0].solution);

            return ('The solution is: ', results[0].solution)
          });

    }
});

An error message

Error: handler method did not return a value, a promise, or throw an error

is being displayed.

Despite my attempt to return

('The solution is: ', results[0].solution)

, it does not resolve the issue.

The console output shows The solution is: 2, however, an error is received in the browser.

Your help on this matter would be greatly appreciated. Thank you

javascript mysql hapi.js

Answer 1

Answer №1

Starting from Hapi v17, it is necessary for all route handlers to explicitly return something.

The error you are encountering indicates that you are not returning any value because the return statement is within a callback of an asynchronous function, which is separate from the main handler function.

To address this issue, you have a few options available. One approach is to convert your route handler to use async and utilize await for handling asynchronous functions like this:

handler: async function (request, h) {
  const result = await connection.query('SELECT 1 + 1 AS solution');
  return result; // manipulate the SQL result before returning it
}

Please note: This method will only work if your connection.query function returns a Promise instead of a traditional NodeJS-style callback. If it does not, you may want to consider using util.promisify to convert a callback-based function into a Promise, or wrap the function manually with new Promise.

If you prefer not to or cannot use await/async, another option is to convert the function with a callback into a Promise and then return that Promise. However, this approach can lead to nested chaining of .then() statements.

const { promisify } = require('util');

[...]

handler: function (request, h) {
  const query = promisify(connection.query);

  return query('SELECT fancy SQL')
    .then(result => {
      // process the SQL result
     return result;
    });
}

In this scenario, the final return value of your route will be the last return value within the last .then block.

Answer 2

Starting from Hapi v17, it is necessary for all route handlers to explicitly return something.

The error you are encountering indicates that you are not returning any value because the return statement is within a callback of an asynchronous function, which is separate from the main handler function.

To address this issue, you have a few options available. One approach is to convert your route handler to use async and utilize await for handling asynchronous functions like this:

handler: async function (request, h) {
  const result = await connection.query('SELECT 1 + 1 AS solution');
  return result; // manipulate the SQL result before returning it
}

Please note: This method will only work if your connection.query function returns a Promise instead of a traditional NodeJS-style callback. If it does not, you may want to consider using util.promisify to convert a callback-based function into a Promise, or wrap the function manually with new Promise.

If you prefer not to or cannot use await/async, another option is to convert the function with a callback into a Promise and then return that Promise. However, this approach can lead to nested chaining of .then() statements.

const { promisify } = require('util');

[...]

handler: function (request, h) {
  const query = promisify(connection.query);

  return query('SELECT fancy SQL')
    .then(result => {
      // process the SQL result
     return result;
    });
}

In this scenario, the final return value of your route will be the last return value within the last .then block.

Answer 3

Answer №2

Consider implementing async/await

server.route({
    method: 'GET',
    path: '/hello',
    handler:async function (request, h) {

        try {
            const { credentials, artifacts } = await request.server.auth.test('default', request);
            return { status: true, user: credentials.name };
        }
        catch (err) {
            return { status: false };
        }
    }
});

Answer 4

Consider implementing async/await

server.route({
    method: 'GET',
    path: '/hello',
    handler:async function (request, h) {

        try {
            const { credentials, artifacts } = await request.server.auth.test('default', request);
            return { status: true, user: credentials.name };
        }
        catch (err) {
            return { status: false };
        }
    }
});

Answer 5

Answer №3

To tackle this issue, I transformed my callback function into a promise for better handling.

  handler: (request, h) => {


                return new Promise ((resolve, reject)=> {

                    connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
                         if (error) throw error;
                         console.log('The solution is: ', results[0].solution);
                         let solution = 'The solution is: ' + results[0].solution
                         let view = () => {
                             return  h.view('landing-page', {solution: solution});
                         }

                         return resolve(view())
                       });


                })


            }

My challenge lies not in the specifics of using hapi or mysql, but rather in honing my expertise in JavaScript.

Answer 6

To tackle this issue, I transformed my callback function into a promise for better handling.

  handler: (request, h) => {


                return new Promise ((resolve, reject)=> {

                    connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
                         if (error) throw error;
                         console.log('The solution is: ', results[0].solution);
                         let solution = 'The solution is: ' + results[0].solution
                         let view = () => {
                             return  h.view('landing-page', {solution: solution});
                         }

                         return resolve(view())
                       });


                })


            }

My challenge lies not in the specifics of using hapi or mysql, but rather in honing my expertise in JavaScript.

The Hapi handler function is failing to return a result

Answer №1

Answer №2

Answer №3

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