I would like to set the default value of a particualr field to null i.e., firestore null when i create a document in firestore. There are other fields which are going to be populated , however, this one field i need as null in order for me to run a query later on in which i want to find all the documents in a firestore collection which has null for this particular field.
for example: Subscriptions collection
customer_id: xyz
subscription_id: null
How do i go about going the above