how to add new data to existing map in firebase flutter

Question

here is the firebase document data

I want to add a new map value to the purchased-id. this is the current code

FirebaseFirestore.instance.collection('users').doc(userID).set({ 'purchased-id': { widget.head: widget.id, } });

but with this code the map value is replaced, how do I add another map value to the existing map

like this

Shri Hari L · Accepted Answer · 2022-05-21 08:33:08Z

I think need merge: true to update the map with its new value.

FirebaseFirestore.instance.collection('users').doc(userID).set({ 'purchased-id': { widget.head: widget.id, } }, SetOptions(merge: true));

Also to differentiate with .set and .update, have a look at this answer: https://stackoverflow.com/a/47554197/11566161

widget.head: widget.id, how can i use the template string instead of widget.id
If you are asking about string interpolation in dart, then it same as assigning above: widget.head: "Key: ${widget.id}"

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