Proposal: refactor validtors of cobra commond args

[aFlyBird0]

Description

To make validators more elegant:

1. I want to separate args validators and important business code.
2. I want to reduce duplicate code of validators.

Describe the Proposal

1. For code separate
   take show cmd for example:

func showCMDFunc(cmd *cobra.Command, args []string) {
	if err := validateShowArgs(args); err != nil {
		log.Fatal(err)
	}

	// There is important business code
}

I will delete code like if err:= validate...Show(args); err!=nil{log.Fatal(err) in all commonds.

New code will be like:

var showCMD = &cobra.Command{
	Use:   "...",
	Short: "...",
	Long: `...`,
	Run: WithValidators(showCMDFunc, validator1, validator2),
}

func showCMDFunc(cmd *cobra.Command, args []string) {
	// Only important business code and following business errors
}

2. For duplicate code
   There is duplicate code like:

if len(args) != 1 {
		return fmt.Errorf("illegal args count (expect 1, got %d)", len(args))
	}

I will define some common validators to program easier and keep error messages consistent.

However, I'am not sure where to put code about validators interface, maybe /cmd/devstream/validator/validator.go ? Or just in /cmd/devstream/validator.go to hide pkg names. Can you give me some advice? @daniel-hutao

Has the Feature been Requested Before?

Describe the Alternatives You Have Considered

Additional Context

[daniel-hutao]

/cmd/devstream/validator/validator.go looks better. Because maybe we'll add many validators in some separated go file under the validator dir. @aFlyBird0

[IronCore864]

Hi @aFlyBird0, thanks for your enthusiastic contribution!

I have read your PR already; sorry for the late reply. I'll reply directly to the issue instead of in the PR.

We follow the standard go project layout, and according to those conventions, the cmd folder shouldn't contain a lot of code.

If you think the code can be imported and used in other projects, then it should live in the /pkg directory. If the code is not reusable or if you don't want others to reuse it, put that code in the /internal directory.

In this case, I think the validator.go file is better to be put under /internal/pkg. Maybe even a new subfolder there?

Feel free to have a discussion here or in our WeChat user group or slack channel :)

Thanks again @aFlyBird0

[daniel-hutao]

@aFlyBird0

[daniel-hutao]

@IronCore864 @aFlyBird0

The validator is a kind of entry logic. So it is more suitable under cmd. For example, k8s does this:

[aFlyBird0]

Thank you both for your advice. @daniel-hutao @IronCore864 I have finished coding

[daniel-hutao]

closed by #479