Aggregate nested json value of hidden field

#1

I saw this answer about aggregating a field from nested json, but when I try to do so with a hidden field prefixed by __, I get the “Could not access blank value” message in the payload. Is there a way to aggregate nested hidden fields?

#2

Hi can you post some screenshots of what you are trying to do?
are you putting JSON in a hidden field? how are you referencing the field in your formula

#3

Thanks for replying!

Here’s a screenshot of a minimal example. When I generate, the thing.total field appropriately sums the ‘a_number’ field, but the thing.hidden_total field just generates “error: Could not access blank value: Use || to provide a default value for blank fields. Example: (my_field || 0) + 1”

mockaroooooo
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#4

Here’s an example of aggregating an attribute in an array: https://www.mockaroo.com/b6fe2a30.

I use the following formula:

items.map {|item| item["price"]}.sum

Your example is slightly more complicated because it has nested arrays. Here’s an example which shows you how to do that:

https://www.mockaroo.com/351243d0

#5

So it looks like that runs into the same issue - if the field to sum is NOT hidden, it works fine, but if it references a hidden field it returns the “Could not access blank value” message.

#6

Yes, that appears to be correct. Nested arrays are generated and hidden values are removed before they are made available to the parent. So you cannot aggregate on a hidden value.

There is, however, another way to hide the field after aggregation, by using an inline formula on the outer array. I’ve updated the example to show this:

https://www.mockaroo.com/351243d0

The inline formula for the outer array is:

this.map do |outer|
  outer.merge({
    items: outer["items"].map do |item|
      item.delete("price")
      item
    end,
  })
end
#7

That looks promising! But I don’t seem to have access to the example.

#8

Sorry, I posted the wrong link. Here you go: Mockaroo - Random Data Generator and API Mocking Tool | JSON / CSV / SQL / Excel

#9

This seems close, but it’s producing an unwanted copy of the “items” array after the total:

{
  "id": 1,
  "outer": [
    {
      "items": [
        {
        },
        {
        }
      ],
      "total": 89.92,
      "items": [
        {
        },
        {
        }
      ]
    }
  ]
}, {
  "id": 2,
  "outer":... [

Unfortunately Ruby is not a language I’ve used before, but the code seems to look right? I’m not sure what the line “item” does after the item.delete() line, but if I remove that I still get an extra array, this time with the numerical values that were deleted.