Can write, but can't read Firestore doc

November 10, 2022

I am wondering, why can I write data to Firestore with addDoc and can’t read that with onSnapshot()

// CheckoutForm.js

import { addDoc, setDoc, doc, onSnapshot, collection, getDoc } from "firebase/firestore"; 
import { firestore } from "../../firebase";
import { getStripe } from "./initializeStripe";

export async function createCheckoutSession(uid) {
  // Create a new checkout session in the subollection inside this users document

  await addDoc(collection(firestore, "users", `${uid}`, "checkout_sessions"), {
    price: "price_1M0jbXFlIMqx6x27XApjUcnp",
    success_url: window.location.origin,
    cancel_url: window.location.origin,
  })

  // Wait for the CheckoutSession to get attached by the extension
  onSnapshot(doc(firestore, "users", `${uid}`, "checkout_sessions"), (doc) => {
    console.log("Current data: ", doc.data());

    const { sessionId } = doc.data();
    if (sessionId) {
      const stripe = await getStripe();
      stripe.redirectToCheckout({ sessionId });
    }
  });
}

So that throw me an error:

Unhandled Promise Rejection: FirebaseError: Invalid document reference. Document references must have an even number of segments, but users/XQRo8Mn0k7awkxCYPTQ7IeWHID93/checkout_sessions has 3

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Before I got some same, when trying write data with setDoc, I still didn’t get why I can’t do it with that, and now the same with onSnapshot(), that need some exactly number of paths.
When I’m writing data using addDoc that give to doc random id so I can’t get into it into.

I’ll be glad for help!

Maksym

>Solution :

As the error suggests, you have 3 segments in your document path that points to a collection and not a document. Here, you can get ID of the newly created document from the result of addDoc and use in onSnapshot as shown below:

const docRef = await addDoc(collection(firestore, "users", `${uid}`, "checkout_sessions"), {
  price: "price_1M0jbXFlIMqx6x27XApjUcnp",
  success_url: window.location.origin,
  cancel_url: window.location.origin,
})

// Wait for the CheckoutSession to get attached by the extension
onSnapshot(doc(firestore, "users", `${uid}`, "checkout_sessions", docRef.id), (doc) => {
  console.log("Current data: ", doc.data());
  // ...
});