consul.kv.keys returns always undefined when an error-handling function is passed

[FrancescoBorzi]

Using version 0.31.0

My method:

async keys(path: string): Promise<string[]> {
    const data = await this.consul.kv.keys(path);
    return data;
}

works fine. However if the path does not exist, a 500 error will be thrown, crashing the application.

If I pass an error handling function:

async keys(path: string): Promise<string[]> {
    const data = await this.consul.kv.keys(path, function(e) {
      console.log(e);
    });
    return data ? data : [];
}

then calling it with a non-existing path will not make the application crash, because the error will be properly handled. However this will make all calls always returning undefined (even with existing paths).

[silas]

You shouldn't mix styles, if you want to use async/await you should use try/catch, if you want to use promises then pass in two functions to then or call catch, and if you want to use callbacks then check for error.

Async/await

const consul = require('consul')({ promisify: true });

const mainAsync = async () => {
  var results;
  try {
    var results = await consul.kv.keys('test');
    console.log(results);
  } catch(error) {
    if (error.statusCode === 404) {
      console.log('not found');
    } else {
      console.log(`other error: ${error.statusCode}: ${error.message}`);
    }
  }
}

mainAsync();

Promise

const consul = require('consul')({ promisify: true });

const mainPromise = () => {
  return consul.kv.keys('test').then(
    (results) => {
      console.log(results);
    },
    (error) => {
      if (error.statusCode === 404) {
        console.log('not found');
      } else {
        console.log(`other error: ${error.statusCode}: ${error.message}`);
      }
    }
  )
}

mainPromise();

Callback

const consul = require('consul')();

const mainCallback = () => {
  consul.kv.keys('test', (error, results) => {
    if (error) {
      if (error.statusCode === 404) {
        console.log('not found');
      } else {
        console.log(`other error: ${error.statusCode}: ${error.message}`);
      }
    } else {
      console.log(results);
    }
  })
}

mainCallback();

[FrancescoBorzi]

I see, thanks. However it would be nice if the documentation was a bit more detailed about the returned type in order to avoid this kind of confusion.