How can I restructure this MongoDB result into the right format? - node.js

Question

I'm querying mongo with something like this:
const loadedLists = await ListValues.find( {} )
I get results back that look more or less like this:
result = [ { listname: 'ListOne',
values: [ {
label: 'OptOne',
cost: '25'
},{
label: 'OptTwo',
cost: '22'
}]
}, { listname: 'ListTwo',
values: [...//and so on]
}]
I need to turn this into an object that looks like this:
const newData =
{ listOne: [ { label: 'OptOne', cost: '25' }, { label ...} ],
listTwo: [ { label: 'OptTwo', cost: '25' }, { label ...} ]}
With the goal of eventually doing Object.assign(res.locals, ...newData) so res.locals has a property of listOne and listTwo.
I've messed around with map like this:
const hh = {}
hh = result.map( async list => {
return { [list.listName]: list.values }
}
hh = await Promise.all(hh)
Which almost works, except hh looks like this:
[
{ listOne: [ ...//Properly has the values ] },
{ listTwo: [ ...//Same...]}
]
I just need to cleanly get those objects moved up a level. I've found NPM modules to do this, or loops to reprocess it, but I can't help but feel like there's a cleaner / tidier way to get it returned.

Answer 1

You need to use reduce
const loadedLists = await ListValues.find( {} )
const hh = loadedList.reduce(
(acc, {listname, values}) => (acc[listname] = values, acc)
{}
)
Also you don't need to scatter async keyword all over the place. :) It makes sense to use it only with async functions that use await keyword.
Example from your code.
// why do you even need async here? there is nothing async in creating an object
hh = result.map( async list => {
return { [list.listName]: list.values }
}

Answer 2

You can use Array.reduce() to accumulate the result.
'use strict';
let data = [{
listname: 'ListOne',
values: [{
label: 'OptOne',
cost: '25'
}, {
label: 'OptTwo',
cost: '22'
}]
}, {
listname: 'ListTwo',
values: [{
label: 'OptOne',
cost: '25'
}, {
label: 'OptTwo',
cost: '22'
}]
}];
let result = data.reduce(function (acc, {listname, values}) {
if (acc[listname]) {
acc[listname] = acc[listname].concat(values);
} else {
acc[listname] = values;
}
return acc;
}, {});
console.log('result', result);
This logs
result { ListOne:
[ { label: 'OptOne', cost: '25' },
{ label: 'OptTwo', cost: '22' } ],
ListTwo:
[ { label: 'OptOne', cost: '25' },
{ label: 'OptTwo', cost: '22' } ] }