[solved] Firestore-array-field into string via derivative-field

[webwurm]

I'm sorry that I ask this question in a different way again - but it bothers me now for a few days and I can't figure it out. Maybe somebody has an idea...

The situation

I have a field in firestore that is an array and stores the references to other documents.
These documents have a field "Bezeichnung" (basically "title") and I want them in the current document put together as a string.

My "solution"

I thought I do the following, since Rowy doesn't support an array in a field:

1. I get the array as JSON-field
2. In the derivative-field I cycle through the json and build the output-string

Sadly I don't even manage to get one item out of the JSON.
The json looks like this:

I tried so many things:

return row.tags.$[0]._key.path.segments[6];
return row.tags[0]._key.path.segments[6];
return row.tags.x[0]._key.path.segments[6];

...and many more versions; nothing works sadly.

My questions

So I have 2 questions:

• Is it a good way what I am trying to do? Or is there a "smarter" way?
• How do I access the JSON, when the root-element is an unnamed array?

Thanks a lot!

[BeeBombshell]

Hey @webwurm, I tried recreating the issue you were facing. Firstly, I created a JSON field and set Default as an array to true. I replicated your tags data, as in the screenshot above, and stored it in a row.

Then, I created another Derivative column and set its Output Field Type to Short Text. Following is the Derivative function I created for displaying a particular element of the segments array:

const derivative:Derivative = async ({row,ref,db,storage,auth})=>{
    const data = row.tags[0]._key.path.segments[0]
    return data
  }

After deploying, the function seems to work perfectly and returns the correct value for the array element.

I wonder what seems to be the issue with your code. Could you share the complete JSON file so that I can help you figure this out?

[webwurm]

Thank you! I tried your solution and it still doesn't work. Here is the JSON, which is in a json-field with "array" checked.
my.txt

My derivative-field (shortText):

const derivative:Derivative = async ({row,ref,db,storage,auth})=>{
  const data = row.tags[0]._key.path.segments[0];
  return data
}

The error:
Cannot read properties of undefined (reading 'path')

[harinij]

Hi @webwurm if this is still an issue, perhaps you can join our upcoming office hours or book a short 1:1 meeting so that we can go over this and get it resolved.

[webwurm]

I got it to work with putting the underline in the path somewhere else - although I don't know why it works, because in the JSON it is "_key.path..." and not "key._path":

tagPath = "ChoiceChips/" + row.tags[i]._path.segments[1];

But it works now, thank you!

[harinij]

Hi @webwurm FYI, we have a new array column type in case that is useful for your usecase.

Documentation: https://docs.rowy.io/field-types/array
Video: https://www.youtube.com/watch?v=-_zQjsIwPx8