How to update nested fields in document without overriding?

[mderevnin]

Hi. I just started using this recently and firstly want to say thank you to all the maintainers for making this happen.

My question is about updating nested fields without overriding the whole field completely. Is there a way to do it in Godot?

Supposing I had this data in the database:

data = {
   "field1": {
      "nested-field1": {
         "data": "keep all of this",
      "nested-field2": {
         "data": "modify this",
      }
   },
   "field2": {
   ...
   }
}

I would like to update the values of nested-field2 without deleting nested-field1.

In the wiki, it says collection.update will update only the fields specified and leave the others untouched. But when I tried, it would override "field1" completely, thus deleting "nested-field1" and just replacing "nested-field2" with what I gave it.

I saw some examples from other languages using firebase where they used dot notation to update a specific nested field only. So I tried putting the add_or_update_field method first argument path to "field1.nested-field2" but dot notation or using a forward slash didn't work. The behavior was strange, sometimes the write was successful but no changes were made. Sometimes the write gave an error.

I looked through the discussions and didn't see anything about this. Hopefully I didn't just overlook something simple.

Thank you!

[WolfgangSenff]

That might just be a bug actually. I'll have to look into it.

[WolfgangSenff]

Can you see what line it's failing on? Something definitely feels odd about what you have there, but I'm struggling to see what.

[mderevnin]

Thanks for having a look. It appears to be failing on:

var task = await collection.update(document)

After the await processes. I'll rewrite it today on a new project to try and figure it out. Hopefully it's some funky setting.

[mderevnin]

I think I figured it out, but I'm not sure what a good solution would be. The problem was having non-alphanumeric characters for field names.

Interestingly using the collection.add for the first time, these non-alphanumeric field names were added successfully. But having them meant that future calls to add_or_update_field would succeed if escaped with `` but with no actual change to the database, or just fail without escaping.

For example:

document.add_or_update_field('あ', "what") # task fails, error code 400
document.add_or_update_field('`あ`', "what") # task succeeds but not actually added to the database
document.add_or_update_field('`test`', "what") # task succeeds but not actually added to the database

# when creating the document for the first time, something like this succeeds
document = await collection.add(auth.localid, {"あ": "test"})
# succeeds and can be retrieved and used, but now no other updates succeed anymore

Is there a way to escape these characters and still be able to use them for field names? I saw some articles online about using "field_path()" in those cases, but it appears specific for their language (not godot).

EDIT:

Seems like add_or_update_field works if the first argument doesn't have special characters, but in the data you pass it, it can be nested with special characters for field names. But also, it will override in these cases. Updating without overriding only works on non-nested fields.

[mderevnin]

Just an update so if anyone in the future sees this, they can benefit from what I ended with.

It seems escaping field names doesn't quite work. It reports success but nothing changes in the database. Using simple field names works fine. So instead I generated a unique ID to use as the field name and kept a look up table of unique IDs to what I originally planned to put, which has characters that aren't allowed without escaping.

See https://firebase.google.com/docs/firestore/quotas#limits for more information. Under "Constraints on field paths", it describes what counts as a simple field name.

For the issue of overriding, it seems like only the very first level you can add and update without overriding. If you go 1 level deeper, it will override all the data. I think the current implementation doesn't have the ability to merge by using dot notation or by adding merge to true as a setting when updating. So for me, I just redesigned my database to work around this by using more than 1 collection instead of previously having various fields represent different collections in one database.

If in the future, I look more into the GodotFirebase source code and figure out how to add some of this stuff, I'll update here. My current understanding isn't high enough for it and while I was able to fix the merge problem, I ultimately didn't go with it because the solution I used was inefficient, had bugs, and more importantly, definitely not the intended way.