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Functions

Functions in Pikku serve as a core interface for the application. They manage logic, interact with services, and handle data processing. Functions are highly flexible and can:

  • Accept arguments
  • Return objects
  • Interact with services
  • Throw errors

Function-Centric Approach​

In Pikku, functions often act as a service layer, interacting with databases or caches. Since they are independent of HTTP, the core logic is typically placed directly within the functions.

Here’s an example of a simple function that retrieves a book using kysely:

const getBook: APIFunction<JustBookId, Book> = async (services, data) => {
  return await services.database
    .selectFrom('book')
    .selectAll()
    .where('bookId', '=', data.bookId)
    .executeTakeFirstOrThrow(() => new NotFoundError());
};

Service-Oriented Approach​

You can also use a service-driven approach, similar to frameworks like NestJS. In this case, functions interact directly with services to perform specific actions.

const getBook: APIFunction<JustBookId, Book> = async (services, data) => {
  return await services.books.getBook(data.id);
};
info

If you follow this approach, it could make sense to embed the function directly in the binding to reduce functions.

const getBook: APIFunction<JustBookId, Book> = async (services, data) => {
  return await services.books.getBook(data.id);
};

Error Handling​

A more detailed explanation of error handling will be covered here. It's worth noting that errors are thrown as they are in a normal javascript project. Pikku then maps it to the correct response depending on the protocol.

HTTP Access in Functions​

To access HTTP-related elements (such as request or response objects), a HTTP service is created. This service abstracts HTTP details, allowing for:

  • Easier testing through stubbing
  • Flexibility across different deployment frameworks and servers
  • Clearer and more manageable API interfaces

Summary​

Functions in Pikku provide a consistent and flexible way to manage services, data, and HTTP requests. The next section will explain how these functions are connected to actual HTTP routes, offering developers a seamless experience.