From plain text to JSON with jq

Most data in my work world is JSON, and so I use a lot of tools designed for that format. For example, we maintain (and use, all the time) an activity parser that is designed for Gnip's Activity Stream data format from a half dozen different platforms. It handles all the assorted messages you might get from the API, and lets you pick and choose the output, among other things.

A relatively new arrow in my quiver of tools at work is jq, a fast and easy command-line JSON parser. This particular quote on the website is the best summary:

jq is like sed for JSON data – you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text.

I recently wrote on an article for our support site about using jq; a kind of "tips and tricks with jq". This gave me a great opportunity to experiment with something I'd been curious about: can jq be used to create JSON structures?

Spoiler alert: the answer is yes!

You can click over there if you'd like to read the full article, but I'll add the punch line here. With a combination of split, map, the right command-line arguments, and an alias, I now use this regularly:

$ cat rules.txt     # tab-separated columns
dog lang:en tag:dogs:english
cat sample:10   tag:cats:0.1
from:gnip   tag:user:gnip

$ jqrules rules.txt
  "rules": [
      "value": "dog lang:en",
      "tag": "tag:dogs:english"
      "value": "cat sample:10",
      "tag": "tag:cats:0.1"
      "value": "from:gnip",
      "tag": "tag:user:gnip"

If you skim through the documentation, it's clear that jq can do a ton of awesome things; every time I learn a new one, it's a great boost in productivity. Happy JSON parsing (and, now, creating)!

Go Top
comments powered by Disqus