Updating a Document

Updating a document in Firestore can be achieved using both the Web (Client) and the Admin SDK (Server). Depending on the use-case, you will use one or the other.

1. Client SDK: When you want to update a document from the browser, you will use the Client SDK. This is the most common use-case, and can be done when the user has the permissions required to update a document based on their security rules.
2. Admin SDK: When you want to update a document from a server, you will use the Admin SDK. This is useful when you want to update a document from a server, or when you want to update a document that the user does not have permission to update.

Client SDK

To update a Firestore document, we will use the addDoc function from the Web Firebase SDK.

We can use hooks to make sure we have access to the Firestore instance, and the collection we want to add the document to.

import { useFirestore } from 'reactfire';
import { useCallback } from 'react';
import { updateDoc, doc } from "firebase/firestore";
function useUpdateTask(id: string) {
  const firestore = useFirestore();
  const tasksDoc = doc(firestore, `/tasks`, id);
  return useCallback(
    (task: {
      title: string;
      description: string;
      completed: boolean;
    }) => {
      return updateDoc(tasksDoc, task);
    },
    [tasksDoc]
  );
}

We can then use this hook in our component to create a new task.

import { useCallback } from "react";
const UpdateTaskForm = ({ id }: { id: string }) => {
  const updateTask = useUpdateTask(id);
  // ... other code
  const onSubmit = useCallback(async (task: {
    title: string;
    description: string;
    completed: boolean;
  }) => {
    await updateTask(task);
  }, [updateTask]);
  // ... other code
};

Admin SDK

To create a document, we will use the update function from the Admin Firebase SDK.

We can use the Admin SDK only in API Route handlers and the getServerSideProps function. For two reasons:

1. The Admin SDK is for Node.js environments, and cannot be used in the browser.
2. The Admin SDK requires a service account, which should not be exposed to the browser.

import getRestFirestore from '~/core/firebase/admin/get-rest-firestore';
async function updateTaskFromServer(task: {
  id: string;
  title: string;
  description: string;
  completed: boolean;
}) {
  const firestore = getRestFirestore();
  const taskRef = firestore.collection(firestore, `tasks`).doc(task.id);
  await taskRef.update(task);
  return task;
}

You can now use the function updateTaskFromServer in your API Route handlers and getServerSideProps functions.