zet

Use `yqlib` to Add YAML Selection

Let’s say you want the power of jq and yq like selection syntax for your YAML files. Turns out that the creators of yq have gracefully exposed yqlib so that we can use it directly. I may not agree with several of their design decisions, but it doesn’t matter. This works (at least until I can get PEGN and scan.X fully working so this stuff becomes trivial once you have a proper spec written in PEGN).

Here’s a sample.yaml file:

foo: FOO
bar: BAR
other:
  - one
  - two
  - three

And here’s the code from my https://github.com/rwxrob/lab where I figured it out. It’s anything but pretty, but it fucking works:

package main

import (
	"io"
	"log"
	"os"

	"github.com/mikefarah/yq/v4/pkg/yqlib"
	logging "gopkg.in/op/go-logging.v1"
)

// creating a printer is a pain in the ass, but flexible

func NewYamlPrinter(
	w io.Writer,
	f yqlib.PrinterOutputFormat, // i mean, what the fuck
	unwrap bool,
	colors bool,
	indent int,
	sep bool,
) yqlib.Printer {
	enc := yqlib.NewYamlEncoder(indent, colors, sep, unwrap)
	pwr := yqlib.NewSinglePrinterWriter(w)
	return yqlib.NewPrinter(enc, pwr)
}

func main() {

	// shitty log shit, god i HATE op/go-logging (circa 2012)
	format := logging.MustStringFormatter(
		`%{color}%{time:15:04:05} %{shortfunc} [%{level:.4s}]%{color:reset} %{message}`,
	)
	b1 := logging.NewLogBackend(os.Stderr, "", 0)
	b2 := logging.AddModuleLevel(logging.NewBackendFormatter(b1, format))
	b2.SetLevel(logging.ERROR, "")
	logging.SetBackend(b2)

	ev := yqlib.NewAllAtOnceEvaluator()
	pr := NewYamlPrinter(os.Stdout, yqlib.YamlOutputFormat, true, false, 2, true)
	dc := yqlib.NewYamlDecoder()
	//err := ev.EvaluateFiles(os.Args[1], []string{"sample.yaml"}, pr, true, dc)
	err := ev.EvaluateFiles(os.Args[1], []string{"-"}, pr, true, dc)
	if err != nil {
		log.Print(err)
	}
}

Note that using “-“ gives you UNIX filter input from standard input.

#golang #coding #tips #yaml #yq #yqlib

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zet

Use yqlib to Add YAML Selection

Use `yqlib` to Add YAML Selection