add support for default commands to yargs

[m-mujica]

Hey guys, is there any way to do something like:

yargs.command("*", [module])

similar to commander

I found https://www.npmjs.com/package/yargs-default-command but does not seem to work with 4.x

Thanks,

[maxrimue]

Hey @m-mujica,

unfortunately, there currently is no official way how to do this in yargs. What do folks think about adding this kind of default command that applies if an unknown command or none is called?

[nexdrew]

I like this idea. Seems like it would help simplify some "control flow" logic with commands, so you don't have to use some sort of custom state to keep track of if a command was executed or not.

[vjpr]

Workaround

  import yargsParser from 'yargs-parser'
  const args = process.argv
  const parsed = yargsParser(args)
  const useDefaultCommand = parsed._.length === 2
  const defaultCommand = 'publish' // <-- set name of your command here
  if (useDefaultCommand && !parsed.help) {
    args.splice(2, 0, defaultCommand)
  }
  const argv = yargs.parse(args)

Its good because you can use all your options for your command, without having to add them to the top level.

Probably need to tweak the help to print your default command info.

---

EDIT

Added !parsed.help to the default command check.

[bcoe]

@nexdrew @m-mujica I like the idea of following prior art, and using * 👍

[nexdrew]

@vjpr brings up a good point.

1. Do we treat the default command just like a hidden command, so it can still apply config for options, validation, etc?
2. Should it affect usage/help content at all?
3. Can I mark a regular named command as the default?

[bcoe]

@timoxley closed #719 in favor of this; I continue to wish we had a simple method like defaultCommand() that would allow a default command that fires if no positional arguments are provided; @nexdrew has some really neat ideas around this feature too, surrounding how default commands relate to command aliases.

[bcoe]

Another related ticket: #728

[bcoe]

@ahmadnassri I closed your issue in favor of this one, I would love to figure out what the ideal API would be for handling a default or "top level" command.

[ahmadnassri]

@bcoe thx, I did come across this one, I figured it to be non-related. but if you see them as such, I'll keep watching here.

[maxrimue]

Okay, I'd like to work on this feature to get it landed possibly in v7. My current proposal would be to make default commands happen like this:

• Any existing command with name and handler can get a default: true in its builder
• Command gets called either by name or if no command is supplied
• Help output adds a bold [default] to said command

This way, you have minimal work to set things up and can even still explicitly call the command. We can also avoid making folks duplicate commands like that, in case they want an actual name and default behaviour. What does everyone think?

[bcoe]

@m-mujica @maxrimue @nexdrew, I'm 100% in agreement that having a way to handle default commands in 7.x of yargs should be a goal -- it will make program flow-control much more consistent.

Where I'm not 100% in agreement, is whether we should use the * syntax, or simply introduce a new API method like .defaultCommand('batman'); I could be swayed in either direction.

@nexdrew or @m-mujica perhaps you could create a straw-man pull request for this feature, just to continue the discussion?

[bcoe]

@m-mujica @vjpr @ahmadnassri, hey! update ... we're planning on releasing @nexdrew's implementation of default commands in the next release.

They work essentially like @m-mujica describes:

https://github.com/yargs/yargs#default-commands

I would love your help testing the new feature, before we push it out to more people:

npm cache clear; npm i yargs@next.

[atian25]

@bcoe

seem this feature is undocument at http://yargs.js.org/docs

my mistake, still in next branch.

--

try @next and found an issue, when set a command name to ['start', '*'], then exec my-bin --help will not print other commands help

[nexdrew]

@atian25 Concerning this:

try yargs@next and found an issue, when set a command name to ['start', '*'], then exec my-bin --help will not print other commands help

We're aware of this issue and will have the fix in soon.

Let us know if you find any other oddities or problems. Thanks!