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Comment by d35007

5 hours ago

That’s interesting! Can you say a little more? I find jq’s syntax and semantics to be simple and intuitive. It’s mostly dots, pipes, and brackets. It’s a lot like writing shell pipelines imo. And I tend to use it in the same way. Lots of one-time use invocations, so I spend more time writing jq filters than I spend reading them.

I suspect my use cases are less complex than yours. Or maybe jq just fits the way I think for some reason.

I dream of a world in which all CLI tools produce and consume JSON and we use jq to glue them together. Sounds like that would be a nightmare for you.

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d35007

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randusername  4 hours ago

I'm not GP, I use jq all the time, but I each time I use it I feel like I'm still a beginner because I don't get where I want to go on the first several attempts. Great tool, but IMO it is more intuitive to JSON people that want a CLI tool than CLI people that want a JSON tool. In other words, I have my own preconceptions about how piping should work on the whole thing, not iterating, and it always trips me up.

Here's an example of my white whale, converting JSON arrays to TSV.

cat input.json | jq -S '(first|keys | map({key: ., value: .}) | from_entries), (.[])' | jq -r '[.[]] | @tsv' > out.tsv

  • nh23423fefe  1 hour ago 

        <input.json  jq -S  -r '(first | keys) , (.[]| [.[]]) | @tsv'
    <input.json  # redir
    jq
    -S           # sort
    -r           # raw string out
    '
    (first | keys) # header
    ,              # comma is generator
    (.[] |           # loop input array and bind to .
    [                # construct array
     .[]             # with items being the array of values of the bound object
     ])           
     | @tsv'        # generator binds the above array to . and renders to tsv

  • figmert  2 hours ago

    Here's an easier to understand query for what you're trying to do (at least it's easier to understand for me):

        cat input.json | jq -r '(first | keys) as $cols | $cols, (.[] | [.[$cols[]]]) | @tsv'

    That whole map and from entries throws it off. It's not a good use for what you're doing. tsv expects a bunch of arrays, whereas you're getting a bunch of objects (with the header also being one) and then converting them to arrays. That is an unnecessary step and makes it a little harder to understand.

    • randusername  2 hours ago

      Thanks for sharing, this is much better, though I actually think it is the perfect example to explain something that is brain-slippery about jq

      look at $cols | $cols

      my brain says hmm that's a typo, clearly they meant ; instead of | because nothing is getting piped, we just have two separate statements. Surely the assignment "exhausts the pipeline" and we're only passing null downstream

      the pipelining has some implicit contextual stuff going on that I have to arrive at by trial and error each time since it doesn't fit in my worldview while I'm doing other shell stuff