Firestore display query result in React Native

Question

I am not able to manage correctly the sync, async, and promises part related to Firestore query. I provide you a simplified version of my scenario. I have different categories of items and I want to display all the category with all items related in a particular way. This is defined by the function Display, that accept as a parameter an array, that contains items belonging to a category.

categories=["ct1","ct2"]
....

async function getItems(category){
let items=[]
const snap =  await db.collection("items").where("category","array-contains",category).get()
snap.forEach((doc=>trainers.push(doc.data())))
return items;
}

....

LOOP ON CATEGORIES

Display(getItems(category))

Now the problem is the part of handling Promise. getItems return a promise not an array. How can I solve the problem and passing the data retrieved from Firestore to display function?

developius · Accepted Answer · 2020-11-20 21:59:21Z

1

You need to await your getItems call.

async/await are just syntactic sugar for Promises, so marking a function as async will cause it to return a Promise, which you need to await:

const items = await getItems('ct1')
// items is now an array

answered Nov 20, 2020 at 21:59

developius

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2 Comments

FrancescoFranco Over a year ago

I try it but it is shown this error: Can not use keyword 'await' outside an async function

developius Over a year ago

Can you show a more complete example? You might need to use .then if you're not in an async context, or change the code that calls this so that it can use await

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