CODEWITHSUNDEEP
arraysangulartypescript
Flashman VC
Flashman VC

Reputation: 63

Why does Typescript report a length of 0 when there are 2 items in the array

The response from a Firestore onSnapshot is 2 records which I push into an array named shop.

this.db.collection("Countries").doc("AU")
    .collection("cPostcode").doc(this.searchby)
    .collection(this.shop).where(how, '==', true)
    .onSnapshot(function (querySnapshot) {
        querySnapshot.forEach(function (doc) {
            shop.push(doc.data());
        })
    });
    console.log('shop.length', shop.length, 'Shop', shop);
    if (shop.length) {
        this.shopList = shop; .........

I use shop.length > 0 to know if any data is returned, but even though there are 2 items in the array, shop.length equals to 0.

Output from the console log shows length:2-

shop.length 0 shop []
    0:{ABN: "1", ACN: "2"}
    1:{ABN: "3", ACN: "4"}
    length:2
    __proto__:Array(0)

I have tried putting a flag in the forEach, but it goes out of scope so does the "this.count" variable I tried. I have been working on this on and off for days. I have googled this problem and general Typescript help, but no one else seems to have this problem. What am I doing wrong?

Upvotes: 1

Views: 531

Answers (1)

Fenton
Fenton

Reputation: 250832

To reliably get the length, you need to make sure you wait for a result.

  this.db.collection("Countries").doc("AU")
    .collection("cPostcode").doc(this.searchby)
    .collection(this.shop).where(how, '==', true)
    .onSnapshot((querySnapshot) => {
        // In here, we have data
        querySnapshot.forEach((doc) => {
            shop.push(doc.data());
        });

        console.log('shop.length', shop.length, 'Shop', shop);

        // Therefore, shop.length should work _reliably_
        if (shop.length) {
            alert(shop.length);
        }
  });

Alternatives include using promises, or calling a function when you have the result (rather than just chucking all the code inside that callback function).

Upvotes: 1

Related Questions