CODEWITHSUNDEEP
typescriptfirebasegoogle-cloud-functions
Garren Fitzenreiter
Garren Fitzenreiter

Reputation: 839

Retrieving data in a snapshot.forEach loop

I am attempting to write a firebase cloud function to loop through all children of a particular node, check a different part of the database for it's corresponding data, and adding up all number values.

Basically, I want the cloud function to create a price total of all the items within a list, but using a different part of the database to retrieve the price for that item.

exports.onAddToCart = functions.database.ref('/users/user_cart/{uid}/items').onWrite((change, context) =>{
    let totalCost = 0;
    return admin.database().ref('/users/user_cart/' + context.params.uid + '/items').once('value').then((snapshot) => {
        snapshot.forEach((child) => {
            return admin.database().ref('/serv/' + child.val()).once('value').then((snapshot2) => {
                totalCost += snapshot2.val().price;
            });
            return false;
        });
        return admin.database().ref('/users/user_cart/' + context.params.uid + '/price').set(totalCost);
    });
});

This code does not work

enter image description here

The problem is snapshot.forEach needs to return a boolean and not a promise. How can I accomplish this? Or is this not viable?

Upvotes: 0

Views: 1922

Answers (1)

Garren Fitzenreiter
Garren Fitzenreiter

Reputation: 839

I ended up creating an array of promises that were each mapped to the location of the price

exports.onAddToCart = functions.database.ref('/users/user_cart/{uid}/items').onWrite((change, context) =>{

let totalCost = 0;
const itemList: string[] = [];

return admin.database().ref('/users/user_cart/' + context.params.uid + '/items').once('value').then((snapshot) =>{

    snapshot.forEach((child) => {

        itemList.push(child.val());
        return false;

    })

    return itemList;

}).then((items) => {

    const promiseList: Promise<any>[] = [];

    for (let i = 0; i < items.length; i++){

        promiseList.push(admin.database().ref('/services/' + items[i]).once('value').then((value) =>{

            totalCost += value.val().price;

        }));

    }

    return Promise.all(promiseList);

}).then(() =>{

    return admin.database().ref('/users/user_cart/' + context.params.uid + '/total').set(totalCost);

});

});

Upvotes: 1

Related Questions