Question: how to access task result from outside?

[jfoliveira]

Hi,

Couldn't find in the docs a way to access the result of a task after the task is finished.
Example code that I tried without success:

async listItems() {
    const tasks = new Listr([{
        title: 'Loading items',
        task: async () => {
            const { data: items } = await someRemoteSlowApi.getItems();
            return items;
        }
    }]);

    const remoteItens = await tasks.run();
    console.log('returned items', remoteItens); // outputs `returned items [Object: null prototype] {}`
}

Is there any way to access the task result remoteItens value after the task has finished?

[jfoliveira]

So, I made a new attempt to set variable values to the task context and try to access it from the outside, but I'm getting the error:
TypeError: Cannot destructure property 'myVariable' of '(intermediate value)' as it is undefined

I've just adapted the exitOnError test method and added a variable to the ctx.

Original code:
https://github.com/SamVerschueren/listr/blob/master/test/exit-on-error.js#L66

My adapted code - with changes highlighted in comments below:

const list = new Listr([
  {
    title: 'foo',
    task: () => Promise.resolve()
  },
  {
    title: 'bar',
    task: () => {
      return new Listr([
        {
          title: 'unicorn',
          task: () => Promise.reject(new Error('Unicorn failed'))
        },
        {
          title: 'rainbow',
          task: (ctx) => {
// CHANGE 1: set ctx property to be accessed from outside the task after the task finishes
            ctx.myVariable = 'my value';
            Promise.resolve();
          }
        }
      ], {
        exitOnError: false // CHANGE 2: I need task `rainbow` to be executed regardless of `unicorn` failing
      });
    }
  },
  {
    title: 'baz',
    task: () => Promise.resolve()
  }
], {
  exitOnError: false // CHANGE 3: not sure if needed, but also tried setting it to `true`
});
try {
  // CHANGE 4: attempt to access the value of `myVariable` that I expected to be in the `ctx`/task result
  const { myVariable: listResult } = await list.run().catch(error => { });
  console.log('list result', listResult);
} catch (error) {
  console.log('Task list failed', error);
}

The above code outputs:
TypeError: Cannot destructure property 'myVariable' of '(intermediate value)' as it is undefined

What am I doing wrong?

[verheyenkoen]

I guess you can chain off a .then() method and work with the returned context there, like so:

list.run()
    .catch(error => { /* … */ })
    .then(ctx => {
        console.log(ctx.myVariable)
    })

Don't know if you can achieve this with async/await.

[verheyenkoen]

Turns out it can work with async/await.

You should be able to do this but just await the result of list.run() and drop the .catch(…) chain as this is handled in the catch block (from inside an async function obviously):

try {
  const { myVariable: listResult } = await list.run();
  console.log('list result', listResult);
} catch (error) {
  console.log('Task list failed', error);
}

[sarink]

Use listr2 https://github.com/cenk1cenk2/listr2 👍