Not able to add a new field to an existing document in firestore

Question

I'm trying to add a new field(reactions) to an existing document using updateDoc method but it's not adding a new field. This is how I'm doing:

      const newUserReactions = [...reactions, newReaction]
      console.log(newUserReactions)
      updateDocument(docID, { reactions: newUserReactions })

reactions field doesn't exist on the document

updateDocument:

const updateDocument = async (id, updates) => {
    dispatch({ type: "IS_PENDING" })
    try {
      const updatedDocument = await updateDoc(doc(db, c, id), updates)
      dispatchIfNotCancelled({ type: "UPDATED_DOCUMENT", payload: updatedDocument })
      return updatedDocument
    } catch (error) {
      dispatchIfNotCancelled({ type: "ERROR", payload: error })
      return null
    }
  }

Answer 1

There are several ways to write data to Cloud Firestore:

• Set the data of a document within a collection, explicitly specifying a document identifier.

• Add a new document to a collection. In this case, Cloud Firestore automatically generates the document identifier.

• Create an empty document with an automatically generated identifier, and assign data to it later.

When you are trying to update a document in Cloud Firestore requires knowing its ID. To update some fields of a document without overwriting the entire document, use the update() method:
You can do the updates by following the below algorithmic logic.
1.Run a query with your conditions to determine the document ID.
2.Update the documents with individual updates, or with one or more batched writes[1]

const docRef = db.collection('objects').doc('some-id');
 
// Update the timestamp field with the value from the server
const res = await docRef.update({
  timestamp: FieldValue.serverTimestamp()
});

Note that you only need the document ID from step 1. So you could run a query that only returns the IDs. This is not possible in the client-side SDKs, but can be done through the REST API and Admin SDKs as shown here [2]

[1] https://firebase.google.com/docs/firestore/manage-data/add-data#server_timestamp
[2] : How to get a list of document IDs in a collection Cloud Firestore?

Are there any specific errors other than the one specified ? Also, please share the pre and the post screen-shot of the Firestore Data from Firebase console.
You may refer the following links for further reference:

[3] : https://firebase.google.com/docs/firestore/manage-data/add-data#add_a_document
[4] : https://firebase.google.com/docs/firestore/manage-data/add-data#set_a_document
[5] : https://cloud.google.com/firestore/docs/samples/firestore-data-set-field#firestore_data_set_field-nodejs [6] : Can I add new fields to existing document if I know its title field value and not the id?