Output formats (json) for lavinmqctl

[viktorerlingsson]

WHAT is this pull request doing?

Adds an option to specify output format (json) for lavinmqctl cmds. Also changes all methods to use the same output method.

Example usage:

$ bin/lavinmqctl list_queues -f json
[{"name":"amq.delayed.delay-test","messages":"0"},{"name":"perf-test","messages":"0"},{"name":"delay-q-test","messages":"0"},{"name":"delay2","messages":"0"},{"name":"q1","messages":"0"},{"name":"q2","messages":"0"},{"name":"federation: ex1 -> viktor-lenovo:/:ex1","messages":"0"}]

HOW can this pull request be tested?

Manual

[carlhoerberg]

Suggested change

	puts first.keys.join("\t")
	puts first.each_key.join(STDOUT, "\t")

[viktorerlingsson]

each_key is expected to be invoked with a block, so this throws an error.
Maybe just puts first.keys.join(STDOUT, "\t") instead?

[spuun]

What types may data contain? Hash#each_key returns an iterator (if not invoked with a block), but NamedTuple#each_key only has one overload that requires a block.

[viktorerlingsson]

data.first will either be a NamedTuple or a JSON::Any

[viktorerlingsson]

so maybe something like this?

        if first.is_a?(NamedTuple)
          puts first.keys.join(STDOUT, "\t")
        elsif first.is_a?(JSON::Any)
          puts first.as_h.each_key.join(STDOUT, "\t")
        end

[spuun]

Yes. But IMO a case statement could is more readable than if statement when doing type checks.

[carlhoerberg]

Suggested change

	values = item.values.map &.to_s
	puts item.each_value.join(STDOUT, "\t")

[viktorerlingsson]

each_value expects to be invoked with a block, so this throws an error. Maybe just print each value instead of the join?

    data.each do |item|
      if item.is_a?(Hash) || item.is_a?(NamedTuple)
        item.each_value { |v| print "#{v}\t" }
      elsif item.is_a?(JSON::Any)
        if hash = item.as_h
          hash.each_value { |v| print "#{v}\t" }
        end
      else
        print item.to_s
      end
      puts
    end

[spuun]

You can do like this:

data.each do |item|
  case item
  when Hash
    item.each_value.join(STDOUT, "\t")
  when JSON::Any
    item.as_h.each_value.join(STDOUT, "\t")
  when NamedTuple
    item.keys.each.join(STDOUT, "\t")
  else
    item.to_s(STDOUT)
  end
  puts
end

NamedTuple#keys returns a tuple, so no allocation.

[viktorerlingsson]

nice 👍 (but we want the values from the NamedTuple so we should use NamedTuple#values instead I guess. Also returns a tuple)

[spuun]

Oh, right! 😁
It was in the previous thread it was keys that was mentioned.

[spuun]

Btw, maybe you can change item.keys.each.join(STDOUT, "\t") to just item.keys.join(STDOUT, "\t")?

[viktorerlingsson]

yes 👍