CODEWITHSUNDEEP
javascriptfirebasegoogle-cloud-firestore
Emil Rotatew
Emil Rotatew

Reputation: 19

firebase / how i can to get a field from all doc's in firestore / javascript

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I need to get data from the "Income" field, which is in each document in collection "values", and write them to array to calculate the sum of the elements of this array.

Upvotes: 1

Views: 982

Answers (1)

Renaud Tarnec
Renaud Tarnec

Reputation: 83068

Do as follows if you want to sum up the values. You don't need an array.

var totalIncome = 0;
db.collection("values").get().then(function(querySnapshot) {
    querySnapshot.forEach(function(doc) {
        totalIncome += doc.data().Income;
    });
    console.log(totalIncome);
});

Be aware however that it will cost a document read for each document of the collection. If your values collection contains a lot of documents, you may use another strategy like updating the totalIncome on documents creation/deletion.

If you really need to populate an array, do as follows:

var totalIncomeArray = [];
db.collection("values").get().then(function(querySnapshot) {
    querySnapshot.forEach(function(doc) {
        totalIncomeArray.push(doc.data().Income);
    });
    //Do whatever you want with the array: it contains all the Income values
});

Upvotes: 2

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