Firestore increment int value if it is exist with flutter

Question

hi guys i am trying to develop an app but i need some help i have a function i just need to do if item is exist on firestore i need to increment "quantity" value of it. i already got and printing the value but i need some help for checker and incrementing value thanks

String checker = await Firestore.instance
        .collection('cart')
        .document('LIihBLtbfuJ8Dy640DPd')
        .get()
        .then((DocumentSnapshot ds) => ds.data[foodItem.name]);
    if (checker == foodItem.name) {
      await Firestore.instance
          .collection('cart')
          .document('LIihBLtbfuJ8Dy640DPd')
          .get()
          .then((DocumentSnapshot ds) =>
              a = ds.data[foodItem.name]['quantity']);

      Firestore.instance
          .collection("cart")
          .document("LIihBLtbfuJ8Dy640DPd")
          .updateData({
        foodItem.name: {'quantity': q++}
      });
    } else {
      Firestore.instance.runTransaction((Transaction transaction) async {
        await transaction.update(
            Firestore.instance
                .collection("cart")
                .document("LIihBLtbfuJ8Dy640DPd"),
            {
              foodItem.name: {
                'itemName': foodItem.name,
                'imgUrl': foodItem.imageAssetPath,
                'itemPrice': foodItem.price,
                'quantity': q,
              }
            });
      });
    }

this is picture of my firestore as you can see there is nested nodes there

Does this answer your question? Firestore Increment FieldValue — Shady Boshra
– Shady Boshra, Commented Apr 2, 2020 at 1:45

wcyankees424 · Accepted Answer · 2020-04-02 04:27:33Z

2

This is what you want to increment a value if the field doesn't exist firebase will create it with the value of 1. I am confused as to the checker part of your question.

Firestore.instance.collection("cart")
.document("LIihBLtbfuJ8Dy640DPd")
.setData({foodItem.name: {"quantity": FieldValue.increment(1)}});

edited Apr 2, 2020 at 4:27

answered Apr 2, 2020 at 1:23

wcyankees424

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7 Comments

Frank van Puffelen Over a year ago

Likely that needs to be: updateData({ 'foodItem.name.quantity': FieldValue.increment(1) }).

Mehmet Reşat Demir Over a year ago

it does not work too because it is nested nodes by the way

wcyankees424 Over a year ago

okay I copy and pasted your code FieldValue.increment(1) works I tried it in my app

Mehmet Reşat Demir Over a year ago

it works but it is outside of the nodes creating new data

Mehmet Reşat Demir Over a year ago

it is not exactly changing my value it does not effect it

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