I’m continuing my efforts to understand the basics of jq by writing posts that a past version of myself would have appreciated. I hope this sort of post helps folks to get their head around core jq mechanisms such as iterators, and also to become more comfortable with the shapes of JSON data that jq reads and writes.

I recently did something similar when processing the output of an AWS CloudWatch logs insights query using the AWS CLI and aws logs get-query-results, where the shape of the data is roughly:

{
  "results": [
    [
      {
        "field": "field1",
        "value": 1
      },
      {
        "field": "field1",
        "value": "foo"
      }
    ]
  ]
}

aws logs get-query-results --region=us-east-1 --query-id $query_id > query-results.json
jq -r \
                '[ .results[] |
                  map(with_entries(if .key == "field" then .key = "key" else . end)) |
                  from_entries ] |
                 (map(keys) | add | unique) as $cols |
                  map(. as $row | $cols | map($row[.])) as $rows | $cols, $rows[] |
                  @csv'  query-results.json > query-results.csv

This is why I created https://fx.wtf, didn’t wanted to learn a new language =)

Got solution in under 1m:

fx entities.json '.value.map(x => Object.values(x).map(JSON.stringify)).join("\n")'