Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/jmcdo29/nest-commander
A module for using NestJS to build up CLI applications
https://github.com/jmcdo29/nest-commander
cli cli-applications cli-command commander hacktoberfest nestjs nestjs-commander
Last synced: about 1 month ago
JSON representation
A module for using NestJS to build up CLI applications
- Host: GitHub
- URL: https://github.com/jmcdo29/nest-commander
- Owner: jmcdo29
- License: mit
- Created: 2021-01-12T08:18:02.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2024-05-06T00:57:58.000Z (6 months ago)
- Last Synced: 2024-05-06T12:24:41.893Z (6 months ago)
- Topics: cli, cli-applications, cli-command, commander, hacktoberfest, nestjs, nestjs-commander
- Language: TypeScript
- Homepage: https://nest-commander.jaymcdoniel.dev/
- Size: 7.84 MB
- Stars: 398
- Watchers: 6
- Forks: 49
- Open Issues: 25
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
 [](http://commitizen.github.io/cz-cli/) [](https://www.buymeacoffee.com/jmcdo29) [](https://codebeat.co/projects/github-com-jmcdo29-nest-commander-main)
# NestJS Commander
Have you been building amazing applications with [NestJS](https://docs.nestjs.com/)? Do you want
that same structure for absolutely everything you're working with? Have you always wanted to build
up some sweet CLI application but don't really know where to start? This is the solution. A package
to bring building CLI applications to the Nest world with the same structure that you already know
and love :heart: Built on top of the popular [Commander](https://github.com/tj/commander.js)
package.
## Installation
Before you get started, you'll need to install a few packages. First and foremost, this one:
`nest-commander` (name pending). You'll also need to install `@nestjs/common` and `@nestjs/core` as
this package makes use of them under the hood, but doesn't want to tie you down to a specific
version, yay peerDependencies!
```sh
npm i nest-commander @nestjs/common @nestjs/core
# OR
yarn add nest-commander @nestjs/common @nestjs/core
# OR
pnpm i nest-commander @nestjs/common @nestjs/core
```
## A Command File
`nest-commander` makes it easy to write new command line applications with
[decorators](https://www.typescriptlang.org/docs/handbook/decorators.html) via the `@Command()`
decorator for classes and the `@Option()` decorator for methods of that class. Every command file
_should_ implement the `CommandRunner` abstract class and _should_ be decorated with a `@Command()`
decorator.
### CommandRunner
Every command is seen as an `@Injectable()` by Nest, so your normal Dependency Injection still works
as you would expect it to (woohoo!). The only thing to take note of is the abstract class
`CommandRunner`, which should be implemented by each command. The `CommandRunner` abstract class
ensures that all commands have a `run` method that return a `Promise` and takes in the
parameters `string[], Record`. The `run` command is where you can kick all of your
logic off from, it will take in whatever parameters did not match option flags and pass them in as
an array, just in case you are really meaning to work with multiple parameters. As for the options,
the `Record`, the names of these properties match the `name` property given to the
`@Option()` decorators, while their value matches the return of the option handler. If you'd like
better type safety, you are welcome to create an interface for your options as well. You can view
how the [Basic Command test](./integration/basic/src/basic.command.ts) manages that if interested.
### @Command()
The `@Command()` decorator is to define what CLI command the class is going to manage and take care
of. The decorator takes in an object to define properties of the command. The options passed here
would be the same as the options passed to a new `command` for Commander
| property | type | required | description |
| --------------- | ---------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| name | string | true | the name of the command |
| arguments | string | false | Named arguments for the command to work with. These can be required `<>` or optional `[]`, but do not map to an option like a flag does |
| description | string | false | the description of the command. This will be used by the `--help` or `-h` flags to have a formalized way of what to print out |
| argsDescription | Record | false | An object containing the description of each argument. This will be used by `-h` or `--help` |
| Options | CommandOptions | false | Extra options to pass on down to commander |
For mor information on the `@Command()` and `@Option()` parameters, check out the
[Commander docs](https://github.com/tj/commander.js).
### @Option()
Often times you're not just running a single command with a single input, but rather you're running
a command with multiple options and flags. Think of something like `git commit`: you can pass a
`--amend` flag, a `-m` flag, or even `-a`, all of these change how the command runs. These flags are
able to be set for each command using the `@Option()` decorator on a method for how that flag should
be parsed. Do note that every command sent in via the command line is a raw string, so if you need
to transform that string to a number or a boolean, or any other type, this handler is where it can
be done. See the [putting it all together](#putting-it-all-together) for an example. The `@Option()`
decorator, like the `@Command()` one, takes in an object of options defined in the table below
| property | type | required | description |
| ------------ | ----------------- | -------- | ------------------------------------------------------------------------------------------------------------------- |
| flags | string | true | a string that represents the option's incoming flag and if the option is required (using <>) or optional (using []) |
| description | string | false | the description of the option, used if adding a `--help` flag |
| defaultValue | string or boolean | false | the default value for the flag |
Under the hood, the method that the`@Option()` is decorating is the custom parser passed to
commander for how the value should be parsed. This means if you want to parse a boolean value, the
best way to do so would be to use `JSON.parse(val)` as `Boolean('false')` actually returns `true`
instead of the expected `false`.
## Running the Command
Similar to how in a NestJS application we can use the `NestFactory` to create a server for us, and
run it using `listen`, the `nest-commander` package exposes a simple to use API to run your server.
Import the `CommandFactory` and use the `static` method `run` and pass in the root module of your
application. This would probably look like below
```ts
import { CommandFactory } from 'nest-commander';
import { AppModule } from './app.module';
async function bootstrap() {
await CommandFactory.run(AppModule);
}
bootstrap();
```
By default, Nest's logger is disabled when using the `CommandFactory`. It's possible to provide it
though, as the second argument to the `run` function. You can either provide a custom NestJS logger,
or an array of log levels you want to keep - it might be useful to at least provide `['error']`
here, if you only want to print out Nest's error logs.
```ts
import { CommandFactory } from 'nest-commander';
import { AppModule } from './app.module';
import { LogService } './log.service';
async function bootstrap() {
await CommandFactory.run(AppModule, new LogService());
// or, if you only want to print Nest's warnings and errors
await CommandFactory.run(AppModule, ['warn', 'error']);
}
bootstrap();
```
And that's it. Under the hood, `CommandFactory` will worry about calling `NestFactory` for you and
calling `app.close()` when necessary, so you shouldn't need to worry about memory leaks there. If
you need to add in some error handling, there's always `try/catch` wrapping the `run` command, or
you can chain on some `.catch()` method to the `bootstrap()` call.
## Testing
So what's the use of writing a super awesome command line script if you can't test it super easily,
right? Fortunately, `nest-commander` has some utilities you can make use of that fits in perfectly
with the NestJS ecosystem, it'll feel right at home to any Nestlings out there. Instead of using the
`CommandFactory` for building the command in test mode, you can use `CommandTestFactory` and pass in
your metadata, very similarly to how `Test.createTestingModule` from `@nestjs/testing` works. In
fact, it uses this package under the hood. You're also still able to chain on the `overrideProvider`
methods before calling `compile()` so you can swap out DI pieces right in the test.
[A nice example of this can be seen in the basic.command.factory.spec.ts file](./integration/basic/test/basic.command.factory.spec.ts).
## Putting it All Together
The following class would equate to having a CLI command that can take in the subcommand `basic` or
be called directly, with `-n`, `-s`, and `-b` (along with their long flags) all being supported and
with custom parsers for each option. The `--help` flag is also supported, as is customary with
commander.
```ts
import { Command, CommandRunner, Option } from 'nest-commander';
import { LogService } from './log.service';
interface BasicCommandOptions {
string?: string;
boolean?: boolean;
number?: number;
}
@Command({ name: 'basic', description: 'A parameter parse' })
export class BasicCommand extends CommandRunner {
constructor(private readonly logService: LogService) {
super();
}
async run(passedParam: string[], options?: BasicCommandOptions): Promise {
if (options?.boolean !== undefined && options?.boolean !== null) {
this.runWithBoolean(passedParam, options.boolean);
} else if (options?.number) {
this.runWithNumber(passedParam, options.number);
} else if (options?.string) {
this.runWithString(passedParam, options.string);
} else {
this.runWithNone(passedParam);
}
}
@Option({
flags: '-n, --number [number]',
description: 'A basic number parser'
})
parseNumber(val: string): number {
return Number(val);
}
@Option({
flags: '-s, --string [string]',
description: 'A string return'
})
parseString(val: string): string {
return val;
}
@Option({
flags: '-b, --boolean [boolean]',
description: 'A boolean parser'
})
parseBoolean(val: string): boolean {
return JSON.parse(val);
}
runWithString(param: string[], option: string): void {
this.logService.log({ param, string: option });
}
runWithNumber(param: string[], option: number): void {
this.logService.log({ param, number: option });
}
runWithBoolean(param: string[], option: boolean): void {
this.logService.log({ param, boolean: option });
}
runWithNone(param: string[]): void {
this.logService.log({ param });
}
}
```
Make sure the command class is added to a module
```ts
@Module({
providers: [LogService, BasicCommand]
})
export class AppModule {}
```
And now to be able to run the CLI in your main.ts you can do the following
```ts
async function bootstrap() {
await CommandFactory.run(AppModule);
}
bootstrap();
```
And just like that, you've got a command line application.
## License
This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.