Hacker News Reader

Comment by js2 | Hacker News Reader

Make JSON greppable!

I've been using `jq` for years and I'm always able to cobble together what I need, but I have yet to find it intuitive and I'm rarely able to arrive at a solution of any complexity without spending a lot of time reading its documentation. I wish I found it easier to use. :-(

View on HN

I also love gron, if nothing else to find the paths I need to use with jq later.

But ChatGPT has genuinely solved my suffering writing jq, it does a pretty good job. It even almost replaces gron, if you feed it an exmaple json and ask for jq, it gives you something. It usually needs a little adjusting but it gets me 90% of the way there and saves me a bit of time.

I rarely use it for much else but its a jq winner :)

jq can be used trivially to approach gron-like output:

  jq -r 'paths(scalars) as $p | getpath($p) | "\($p|join(".")) = \(.)"'

See elsewhere in this subthread for a full gron implementation in jq.

'Trivially'

Start with `jq -c 'paths(scalars)` -- that's pretty trivial.

I think parent is referring to the habit of technically inclined folks of using "trivially" similar to words like "simply" and "just" [0][1] in a way that assumes too much about what the reader already knows.

[0] https://www.parkersoftware.com/blog/stop-using-simply-in-tec...

[1] https://news.ycombinator.com/item?id=35759449

Or maybe I'm trying to whet one's appetite for learning the thing by showing a relatively simple expression that demonstrates the power of the language.

You can trivially approximate gron with jq, and you there are jq implementations of gron too, like https://gist.github.com/mkfmnn/7b637aa0ec9b0422b3b75ec181a13...

E.g.,

  # gron
  gron "https://api.github.com/repos/tomnomnom/gron/commits?per_page=1" |
  fgrep commit.author
  json[0].commit.author = {};
  json[0].commit.author.date = "2016-07-02T10:51:21Z";
  json[0].commit.author.email = "mail@tomnomnom.com";
  json[0].commit.author.name = "Tom Hudson";

  # jq
  curl -L "https://api.github.com/repos/tomnomnom/gron/commits?per_page=1" |
  jq -r 'paths(scalars) as $p | getpath($p) | "\($p|join(".")|select(contains("commit.author"))) = \(.)"'
  0.commit.author.name = Tom Hudson
  0.commit.author.email = mail@tomnomnom.com
  0.commit.author.date = 2022-04-13T14:23:37Z

  # jq with grep outside jq
  curl -L "https://api.github.com/repos/tomnomnom/gron/commits?per_page=1" |
  jq -r 'paths(scalars) as $p | getpath($p) | "\($p|join(".")) = \(.)"' |
  fgrep commit.author
  0.commit.author.name = Tom Hudson
  0.commit.author.email = mail@tomnomnom.com
  0.commit.author.date = 2022-04-13T14:23:37Z

With just a bit more work you can get it to output valid gron, and even to parse valid gron.

Looks handy, but I'd rather go the other way and extend grep (and diff, etc.) to also work on things that aren't restricted to be lines in a text file. The number of times I've needed to go through contortions for things that should be easy solved problems (e.g., grepping for patterns of line pairs, grepping for records that use a different delimiter when the record data itself could contain linefeed, etc.)...

Tip for pairs of lines. Use grep -A, -B, or -C to emit lines surrounding the first line to match, then pipe that into a second grep (also with -A, -B or -C). e.g.

  grep -A1 foo | grep -B1 bar

Will find a line with "foo" followed by a line with "bar" and emit both. Of course, it will also find a single line with both "foo" and "bar", so it's not perfect. This is a quick and dirty solution. Beyond that, break out sed and awk, or maybe the Practical Extraction and Report Language... it's really good at that stuff.

Thanks, it's a brittle hack as you acknowledge but at least there won't be false negatives. Funny how often I wind up crawling back to Perl.

The problem here is literally that someone hardcoded "IT'S ALWAYS LINEFEED" into an algorithm that could work equally well with any record separator character -- in fact probably with any record separator regex. I notice there's now `grep -z` which is one small step towards sanity... but the fully general problem is so easy and so useful to solve it's exasperating.

I guess I should stop complaining and submit a patch to grep to add a `--dont-use-linefeed-instead-use <arg>` option already.

Reply on news.ycombinator.com