summercms/docs/console/writing-commands.md

---
title: Writing commands
description: Add console commands to a plugin with bonfire.Command values, arguments, flags, styled output and prompts, and run commands in-process.
section: console
order: 40
---
# Writing commands

A plugin adds console commands to the application binary the way a WinterCMS plugin calls `registerConsoleCommand`. In SummerCMS a command is a plain `bonfire.Command` value, and the plugin returns its commands from `pact.HasCommands`. `summer make:command acme.blog Publish` generates a starting point in `console/publish.go`.

## Defining a command

A `bonfire.Command` has a name, a description, its positional arguments and flags, and a run function:

- The name is in `namespace:verb` form, such as `blog:publish`. Plugin commands must use this form; only a few framework commands have bare names.
- Each `bonfire.Arg` is a positional argument with a name, a description and a `Required` marker. The usage line shows required arguments as `<name>` and optional ones as `[name]`.
- Each `bonfire.Flag` is a string flag. Set `bonfire.Flag.Bare` for a switch such as `--dry-run` that stores `true` when given alone, and `bonfire.Flag.Repeatable` for a flag that can be given several times.
- `bonfire.Command.Run` receives the context, a `bonfire.Input` and a `bonfire.Output`.
- `bonfire.Command.Long` is optional extended help, shown under "Help:" by `help <command>` and `<command> --help`. `bonfire.Command.Examples` and `bonfire.Command.Hidden` are described below. Set `bonfire.Command.Passthrough` for a command that forwards to another program: flag parsing is turned off, so every argument after the command name, including `--help`, `-h` and `--`, reaches `bonfire.Input.Args` unchanged. Declared flags then appear in the usage text only, and declared arguments are not count-checked.

Read arguments with `bonfire.Input.Argument`, scalar and bare flags with `bonfire.Input.Flag`, and repeatable flags with `bonfire.Input.Flags`, which returns the values in the order given:

```go src=modules/bonfire/example_test.go#ExampleCatalog
publish := bonfire.Command{
	Name:        "blog:publish",
	Description: "Publish a post",
	Args:        []bonfire.Arg{{Name: "slug", Description: "Post slug", Required: true}},
	Flags: []bonfire.Flag{
		{Name: "dry-run", Description: "Report without writing", Bare: true},
		{Name: "tag", Description: "Tag to add (repeatable)", Repeatable: true},
	},
	Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
		slug, _ := in.Argument("slug")
		dryRun, _ := in.Flag("dry-run")
		out.Printf("publish %s, tags %v, dry run %s\n", slug, in.Flags("tag"), dryRun)
		return nil
	},
}

// The generated main publishes a catalog of every command on the app.
catalog := bonfire.NewCatalog([]bonfire.Command{publish})
args := []string{"hello-world", "--tag", "news", "--tag", "go", "--dry-run"}
if err := catalog.Call(context.Background(), "blog:publish", args, os.Stdout); err != nil {
	fmt.Println(err)
}
// Output: publish hello-world, tags [news go], dry run true
```

## Registering commands

Return the commands from the plugin's `Commands` method, which implements `pact.HasCommands`. The generated `main` appends every plugin's commands after the framework's runtime commands. Command names must be unique: when two commands share a name, or a command is named `list` or `help`, `bonfire.NewRoot` fails with `bonfire.ErrDuplicateCommand` naming the command, and the binary does not start. Keep your commands in your plugin's own namespace, such as `blog:`. The global options are reserved as well: a flag named `verbose`, `quiet`, `ansi`, `no-ansi`, `no-interaction`, `env` or `help`, or with the shorthand `v`, `q`, `n` or `h`, makes `bonfire.NewRoot` fail with `bonfire.ErrReservedFlag`.

A scaffolded plugin's `Commands` method returns the generated list of everything in `console/`, so commands created with `summer make:command` are registered without editing `plugin.go`.

## Output

`bonfire.Output` is the console your command writes to. Besides `bonfire.Output.Printf` and `bonfire.Output.Println`, it provides:

- status lines: `bonfire.Output.Info`, `bonfire.Output.Success`, `bonfire.Output.Warning` and `bonfire.Output.Error` (the last one writes to the error stream);
- widgets: `bonfire.Output.Table`, `bonfire.Output.Spinner` around a function and `bonfire.Output.Progress` for a progress bar, which fall back to plain lines when the output is not a terminal;
- prompts: `bonfire.Output.Ask`, `bonfire.Output.Confirm`, `bonfire.Output.Choice` and `bonfire.Output.Secret`. Prompts return their defaults when input ends, so a command run from cron or a script never hangs.

Return an error from `Run` to fail the command. The binary prints it as an error block on stderr and exits with status 1; see [Errors and hints](#errors-and-hints).

## Examples and hidden commands

`bonfire.Command.Examples` lists usage examples. Each `bonfire.Example` holds the command line without the binary and a short description; help prints the description as a `#` comment and the line after `bin/<name>` (or `summer` for the tool's own commands), so one example serves both. `bonfire.Command.Hidden` keeps a command that still runs out of the list; `list --all` and `list --format=json` show it:

```go src=modules/bonfire/example_test.go#ExampleExample
export := bonfire.Command{
	Name:        "blog:export",
	Description: "Export published posts as JSON",
	Long:        "Writes every published post, newest first, to a JSON file.",
	Flags: []bonfire.Flag{
		{Name: "path", Description: "Output file", Default: "posts.json"},
	},
	Examples: []bonfire.Example{
		{Command: "blog:export --path=backup.json", Description: "Export to another file"},
	},
	Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
		return nil
	},
}
// Hidden commands run, but list shows them only with --all.
cleanup := bonfire.Command{
	Name:        "blog:cleanup",
	Description: "Remove orphaned uploads",
	Hidden:      true,
}

root, err := bonfire.NewRootIO("acme", []bonfire.Command{export, cleanup}, strings.NewReader(""), os.Stdout, os.Stdout)
if err != nil {
	fmt.Println(err)
	return
}
bonfire.Execute(context.Background(), root, []string{"help", "blog:export"})
// Output:
// Description:
//   Export published posts as JSON
//
// Usage:
//   blog:export [options]
//
// Options:
//       --path=PATH  Output file [default: "posts.json"]
//
// Global options:
//   -h, --help            Display help for the given command
//   -q, --quiet           Do not output any message
//   -v|vv|vvv             Increase verbosity
//       --ansi|no-ansi    Force (or disable) ANSI output
//   -n, --no-interaction  Do not ask any interactive question
//       --env             The environment the command runs under
//
// Help:
//   Writes every published post, newest first, to a JSON file.
//
// Examples:
//   # Export to another file
//   bin/acme blog:export --path=backup.json
```

`list --format=json` prints every command with its arguments, options (with defaults) and examples as a `bonfire.Listing`, for documentation checks, scripts and agents. `bonfire.Describe` builds the same listing from a command slice.

## Errors and hints

When `Run` returns an error, the binary prints a block on stderr: the ERROR badge and the message, then "Run with -v for details.". With `-v` the block lists the wrapped errors under "Caused by:" instead. Messages pass through `sunscreen.Scrub`, so a token inside an error text is not printed.

Wrap an error with `bonfire.WithHint` to explain it and to say what to run next. `{bin}` in the Try text becomes `bin/<name>` or `summer`, so the hint names the right program:

```go src=modules/bonfire/example_test.go#ExampleWithHint
publish := bonfire.Command{
	Name:        "blog:publish",
	Description: "Publish a draft post",
	Args:        []bonfire.Arg{{Name: "slug", Description: "Post slug", Required: true}},
	Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
		slug, _ := in.Argument("slug")
		return bonfire.WithHint(fmt.Errorf("blog: no draft named %q", slug),
			"Only drafts can be published; published posts keep their slug.",
			"{bin} blog:drafts")
	},
}

root, err := bonfire.NewRootIO("acme", []bonfire.Command{publish}, strings.NewReader(""), os.Stdout, os.Stdout)
if err != nil {
	fmt.Println(err)
	return
}
code := bonfire.Execute(context.Background(), root, []string{"blog:publish", "hello-world"})
fmt.Println("exit code:", code)
// Output:
// ERROR  blog: no draft named "hello-world"
//
//   Only drafts can be published; published posts keep their slug.
//
//   Try:
//     bin/acme blog:drafts
//
//   Run with -v for details.
//
// exit code: 1
```

A command that has already printed its problems, such as a checker that lists every finding, returns `bonfire.Reported(err)`: the binary exits 1 and prints nothing more. A mistake in how the command was called, such as an unknown flag or a missing argument, exits 2 and the block suggests `help <command>`; wrap your own usage checks with `bonfire.Usage` to get the same exit code.

## Documentation coverage

`bonfire.CheckDocs` reports each command that lacks a description, long help, an example, or a description of one of its arguments or options. It only reports; the framework's own test fails on any problem, and a plugin repository can call it from a test and log the problems:

```go src=modules/bonfire/example_test.go#ExampleCheckDocs
commands := []bonfire.Command{
	{
		Name:        "blog:publish",
		Description: "Publish a draft post",
		Long:        "Publishes the draft with the given slug and notifies subscribers.",
		Args:        []bonfire.Arg{{Name: "slug", Description: "Post slug", Required: true}},
		Examples:    []bonfire.Example{{Command: "blog:publish hello-world"}},
	},
	{
		Name:        "blog:reindex",
		Description: "Rebuild the search index",
		Flags:       []bonfire.Flag{{Name: "batch", Default: "500"}},
	},
}
for _, problem := range bonfire.CheckDocs(commands) {
	fmt.Println(problem)
}
// Output: blog:reindex: missing long help, examples, option --batch description
```

## Calling commands in-process

`bonfire.Call` runs one command of a slice by name with its arguments and writes the output to any writer, like `Artisan::call` in Laravel. Tests use it to exercise a command without building a binary:

```go src=modules/bonfire/example_test.go#ExampleCall
commands := []bonfire.Command{{
	Name:        "acme:greet",
	Description: "Greet someone by name",
	Args:        []bonfire.Arg{{Name: "name", Required: true}},
	Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
		name, _ := in.Argument("name")
		out.Printf("Hello, %s\n", name)
		return nil
	},
}}

if err := bonfire.Call(context.Background(), commands, "acme:greet", []string{"blog"}, os.Stdout); err != nil {
	fmt.Println(err)
}
// Output: Hello, blog
```

The generated `main` also publishes the application's complete command list as a `bonfire.Catalog` on the container. Code outside the command line, such as the scheduler, looks it up and calls commands through `bonfire.Catalog.Call`, and checks for one with `bonfire.Catalog.Has`.

## Running your command

After `summer build`, your command is part of the binary:

```sh
./bin/hello greeter:hello
```

That command comes from the greeter plugin of `examples/hello`, whose `Commands` method returns one `bonfire.Command`.