What's new in version 2 (part 1/4)

February 17, 2021 · 5 min read

Loïc Poullain

Fullstack developper and creator of FoalTS

This article presents some improvements introduced in version 2 of FoalTS:

the new CLI commands
the service and application initialization
the AppController interface
custom error-handling & hook post functions
accessing file metadata during uploads

This article is the part 1 of the series of articles What's new in version 2.0. Part 2 can be found here.

New CLI commands#

In version 1, there were many commands to use, and this, in a specific order. Running and generating migrations from model changes required four commands and building the whole application needed three.

In version 2, the number of CLI commands has been reduced and they have been simplified so that one action matches one command.

Generating migrations#

This command generates migrations by comparing the current database schema and the latest changes in your models.

Version 2
Version 1

npm run makemigrations

Running migrations#

This command builds and runs all migrations.

Version 2
Version 1

npm run migrations

Build and run scripts in watch mode (development)#

If you want to re-build your scripts each time a file is change, you can execute npm run develop in a separate terminal.

Version 2
Version 1

# In one terminal:
npm run develop

# In another terminal:
foal run my-script

Revert one migration#

This command reverts the last executed migration.

Version 2
Version 1

npm run revertmigration

Build migrations, scripts and the app#

This command builds the application, the scripts and the migrations. Unit and e2e tests are not included.

Version 2
Version 1

npm run build

Service and Application Initialization#

In version 1, it was possible to add an init method to the AppController class and boot methods in the services to initialize the application. These features needed special options in order to be activated.

Starting from version 2, they are enabled by default.

export class AppController {
  // ...

  init() {
    // Execute some code.
  }
}

export class MyService {
  // ...

  boot() {
    // Execute some code.
  }
}

The `AppController` interface#

This optional interface allows you to check that the subControllers property has the correct type as well as the init and handleError methods.

export class AppController implements IAppController {
  subControllers = [
    controller('/api', ApiController)
  ];

  init() {
    // ...
  }

  handleError(error, ctx) {
    // ...
  }
}

Custom Error-Handling & Hook Post Functions#

In version 1, when an error was thrown or rejected in a hook or a controller method, the remaining hook post functions were not executed.

Starting from version 2, the error is directly converted to an HttpResponseInternalServerError and passed to the next post hook functions.

This can be useful in case we want to use exceptions as HTTP responses without breaking the hook post functions.

Example

class PermissionError extends Error {}

class UserService {

  async listUsers(applicant: User): Promise<User[]> {
    if (!ctx.user.isAdmin) {
      // Use exception here.
      throw new PermissionError();
    }

    return User.find({ org: user.org });
  }

}

// This hook measures the execution time and the controller method and hooks.
@Hook(() => {
  const time = process.hrtime();

  // This post function will still be executed
  // even if an error is thrown in listUsers.
  return () => {
    const seconds = process.hrtime(time)[0];
    console.log(`Executed in ${seconds} seconds`);
  };
})
export class AppController {

  @dependency
  users: UserService;

  @Get('/users')
  @UseSessions({ user: fetchUser(User) })
  @UserRequired()
  listUsers(ctx: Context<User>) {
    return new HttpResponseOK(
      await users.listUsers(ctx.user)
    );
  }

  handleError(error: Error, ctx: Context) {
    // Converts the exception to an HTTP response.
    // The error can have been thrown in a service used by the controller.
    if (error instanceof PermissionError) {
      return new HttpResponseForbidden();
    }

    // Returns an HttpResponseInternalServerError.
    return renderError(error, response);
  }
}

Accessing File Metadata during Uploads#

When using the @ValidateMultipartFormDataBody hook to handle file upload, it is now possible to access the file metadata.