Promise.all no return res map nodejs - node.js

Question

We are integrating with Outlook api and we need to group the attachments in the recovered emails:
We re trying this way:
const result = await client
.api('/me/messages')
.filter(searchMailFrom)
.select('subject, from, receivedDateTime, sentDateTime, isRead, toRecipients, hasAttachments')
.get()
let dadosAnexo = result.value.map(async item => {
if (item.hasAttachments) {
const resultAtt = await client
.api('/me/messages/' + item.id + '/attachments')
.get()
item.anexos = resultAtt.value
}
})
await Promise.all(dadosAnexo)
return res.status(200).send(result.value)
But when we put Promise.all (), the system simply returns nothing

Answer 1

You are not returning anything from inside your .map functions. So, dadosAnexo becomes an array of Promises that will each resolve to undefined.
Check the MDN docs for more details about how .map works: Map | MDN.
Then, you are passing dadosAnexo to your Promise.all call.
But when we put Promise.all (), the system simply returns nothing
Here, your assumption is wrong.
await Promise.all(dadosAnexo)
The await Promise.all call above will actually return an array of undefined. Because you are passing it dadosAnexo (an array of Promises, each of which resolves to undefined). Also, you are not assigning the return value to any variable (so, you don't actually know if it's returning something or not).
Check the MDN docs for more details about how Promise.all works: Promise.all() | MDN
Now to solve your problem, here's a solution:
const result = await client
.api('/me/messages')
.filter(searchMailFrom)
.select('subject, from, receivedDateTime, sentDateTime, isRead, toRecipients, hasAttachments')
.get()
// promisesToAttach will be an array containing some Promises and some item values
const promisesToAttach = result.value.map(item => {
if (item.hasAttachments) {
// returning a promise
return client
.api('/me/messages/' + item.id + '/attachments')
.get()
.then(resultAtt => {
item.anexos = resultAtt.value
return item
})
}
// returning an item value
return item
})
// resultWithAttachments will be an array of resolved item values
const resultWithAttachments = await Promise.all(promisesToAttach)
return res.status(200).send(resultWithAttachments)