Flatten a JSON document using jq

This one was a tricky one to craft.

map
(
    with_entries(select(.key != "fields"))
    +
    (.fields | with_entries(.value = .value[0]))
)

Let’s break it down and explain the bits of it

1. For every item in the array…

   map(...)
   

2. Create a new object containing the values for all except the fields property.

   with_entries(select(.key != "fields"))
   

3. Combine that with…

   +
   

4. Each of the fields projecting each of the values to the first item of each array

   (.fields | with_entries(.value = .value[0]))