[Flutter/dart] Update only specific field in Cloud Firestore

Overview

I think that cloud fire store is often used as a destination to store user data in smartphone apps. I would like to introduce some points to be aware of when updating only specific fields in a certain document among the saved data.

Details

Suppose each document in the'items' collection has two fields,'content' and'date'. If you want to update only the'content'field, do as follows.

await db.collection('items').doc('0').set({'content': 'change'}, SetOptions(merge: true));  //here！

It is important to set merge: true in SetOptions on the second line. Without it, the document will be overwritten with new data. (That is, 'date' will be null)

Don't forget to set it if you want to update only one of the multiple fields.