Using async-await with arr.map()
Satej Bidvai
Posted on January 12, 2023
While working on a task today, I had to populate my array of objects using my database.
Instinctively, I used the map function. The code looked something like this:
const dataList = [
{ type: "test__1" },
{ type: "test__2" },
{ type: "test__3" },
{ type: "test__4" }
];
const modifiedList = dataList.map(async (item) => {
// Get additional properties from DB
const dataFromDB = await DataModel.findOne({
type: item.type
});
return { ...item, dataFromDB };
});
❗️ Did you spot the error?
👉🏽 In dataList.map(), we are returning an array of promises and not an array.
👉🏽 Hence, the modifiedList will look something like this:
⚡️ The Solution?
Simple! We just need to wrap our function with await Promise.all so that our array of promises is resolved to the desired modifiedList .
const modifiedList = await Promise.all(
dataList.map(async (item) => {
// Get additional properties from DB
const dataFromDB = await DataModel.findOne({
type: item.type
});
return { ...item, dataFromDB };
});
);
💖 💪 🙅 🚩
Satej Bidvai
Posted on January 12, 2023
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