Formatters

[cpsubrian]

Introduces the concept of 'formatters' and ALL CLI output runs through a formatter.

A formatter is merely a commonjs module that exports an object. The object should follow the following signature:

module.exports = {
  // Required. Outputs lines.
  output: function(lines) {
   // console.log, or write to a file, or whatever.
  },

  // Optional. Map function.
  map: function(obj) {
    return obj.type;
  },

  // Optional. Select function.
  select: function(obj) {
    return obj.level === 'error';
  },

  // Optional. Reduce function.
  reduce: function(lines) {
      // return reduced lines.
  }
};

Formatters can live in three possible locations:

• lib/formatters
• $HOME/.jog/formatters
• $CWD/.jog/formatters

This allows someone to maintain formatters that they like to use on either a per-machine, or per-project basis. Awesome! Also, the formatters are loaded in that order, so project formatters can override machine ones, or core ones.

Four core formatters are included:

• json
• color
• short
• default

You use the formatters via the --output command-line option.

jog -F /tmp/logs.log -f --output short

jog -F /tmp/logs.log -f -o short

-j --json is aliased to --output json

-c --color is aliased to --output color

I think this is a really flexible approach. For example you could create a formatter that saves images, or a formatter that renders a CLI bar chart, or whatever.

[tj]

IMO this should be a concern for custom / other tools / shell scripts

[cpsubrian]

Care to elaborate? The idea is that its simply a way to 'save' jog commands with whatever filtering/formatting that you want. IMO it makes jog way more 'viable' for constant use during development and production.

If this sort of formatting is part of a separate CLI, then whats the point of jog (for my use case). I would probably just create my own jog with customizable formatting built in, but thats the type of module fragmentation that I though its better to avoid.

[cpsubrian]

I mean it would be possible to create a module that just prints json objects such that you would do:

jog -F /tmp/app.log -f --json | jsonprint --format short

But that doesn't let you reuse select or reduce functions at all. So then you have a tool that just wraps the entirety of jog which seems specific and redundant when, IMO, this formatters approach makes jog itself more extendable while adding minimal code.

[tj]

i dont dislike the idea, i just dont want to bloat jog itself, i also want a repl and a query language but that's not going to be built within jog itself. ill take a closer look a the implementation and consider it

[tj]

i dont know, personally I would still just write a little shell script or alias called say ./total-response-time with jog --file cloudup.log --type response --map duration --reduce "$ + _" etc

[cpsubrian]

I guess we have to agree to disagree :) I'll put some more thought into how I can do what I want cleanly without having to fork jog.

[tj]

sounds good. i would even prefer cat some.log | map duration | reduce "$ + _" etc haha, but it would be lots of things to install, perhaps they should all be in one repo but separate executables

[cpsubrian]

I could see that. jsontools or something.

[cpsubrian]

I 'scratched my own itch' and created https://github.com/cpsubrian/node-joli which satisfies my needs. So, unless you think some version of this will be included in jog feel free to close this.