add object data to existing firebase document

Question

I’m having problems finding the the right approach to adding new data to a Firebase document (using JavaScript)

My document structure is as follows..

I want to be able to add a new child (as in kids) and a new class (as in school classes) objects to the children and classes arrays. I tried update, but that just overwrote existing data.

Answer 1

You can use FieldValue.arrayUnion() to add a new element to an array field of a document.