AsyncResult and Result

The AsyncResult and Result classes are foundational utilities in the garden ecosystem. They provide a structured way to handle asynchronous operations and their results, eliminating the need for explicit try-catch blocks in most cases.

The Result class wraps the outcome of a function, while AsyncResult extends this concept for asynchronous operations.

import { AsyncResult, Result, Ok, Err } from '@catalogfi/utils';

Result class

The Result class encapsulates an operation's result, including whether it succeeded and its associated value or error.

Properties

Property	Type	Description
ok	boolean	Indicates whether the operation was successful (true) or failed (false).
val	T	The value returned by a successful operation.
error	E | undefined	The error returned by a failed operation.

Constructor

new Result(ok: boolean, val: T, error?: E | undefined)

AsyncResult Type

The AsyncResult type represents an asynchronous version of Result.

type AsyncResult<T, E> = Promise<Result<T, E>>;

Key Features

• Combines Promise and Result, enabling both asynchronous handling and structured error management.
• Simplifies error handling: instead of try-catch, use res.error to access any errors.

Utility Functions

Ok

Creates a successful Result with the given value.

export const Ok = <T>(val: T): Result<T, never>;

parameters

• val: T - The value to return in the result.

Err

Creates a failed Result with the given error value.

export const Err = <E>(error: E, ...optionalMsg?: string[]): Result<never, E>;

parameters

• error: E - The error value.
• optionalMsg?: string[] - Additional messages to append to the error.

Example: using Ok and Err

//Suppose we have a function fetchData that retrieves
//some data asynchronously and uses AsyncResult for its return type.
async function fetchData(id: string): AsyncResult<{ data: string }, string> {
  if (!id) {
    return Err('Invalid ID provided');
  }

  try {
    const response = await fetch(`https://api.example.com/data/${id}`);
    if (!response.ok) {
      return Err(`Failed to fetch data: ${response.statusText}`);
    }

    const data = await response.json();
    return Ok({ data });
  } catch (error) {
    return Err('Unexpected error occurred', error.message);
  }
}

//Now, you can use fetchData in your application without worrying about error handling.
const result = await fetchData('123');

if (result.ok) {
  console.log('Data fetched successfully:', result.val);
} else {
  console.error('Error fetching data:', result.error);
}