Enum Constant Usage Guide for Akan.js

This guide provides comprehensive instructions for using `enumOf` to create type-safe enumerations in constant files within Akan.js applications.

Overview of enumOf

`enumOf` provides runtime-enforced enumerations with full TypeScript type safety. Key features include type safety, immutable values, utility methods, and seamless MongoDB integration.

1import { enumOf } from "@akanjs/base";
2
3export const MyEnum = enumOf(["value1", "value2"] as const);
4export type MyEnum = enumOf<typeof MyEnum>;

Declaring Enumerations

Use this pattern to declare enums with required `as const` assertion and double export pattern.

1export const Status = enumOf(["active", "pending", "archived"] as const);
2export type Status = enumOf<typeof Status>;

Key Requirements:

`as const` assertion is essential for literal type inference
Values must be declared as a constant array
Double export pattern for constant and type

Using Enums in Models

Field Decorators

1@Field.Prop(() => String, {
2  enum: Status,
3  default: "active"
4})
5status: Status;

Arrays

1@Field.Prop(() => [String], {
2  enum: UserRole
3})
4roles: UserRole[];

Filter Arguments

1@Filter.Mongo()
2filterByStatus(
3  @Filter.Arg("status", () => String, {
4    enum: Status
5  })
6  status: Status
7) {
8  return { status };
9}

Enum Operations and Methods

Value Checking

1Status.has("active"); // true
2Status.has("invalid"); // false

Index Lookup

1Status.indexOf("archived"); // Returns 2

Iteration Methods

1// Find
2Status.find((val) => val.includes("a"));
3
4// Filter
5Status.filter((val) => val.startsWith("a"));
6
7// Map
8Status.map((val) => val.toUpperCase());

Best Practices

Do's

Use simple string literals for enum values
Group related enums near their usage context
Always specify default values in decorators
Use PascalCase for enum names

Don'ts

Don't omit `as const` assertion
Avoid non-constant arrays
Never modify enum values after creation
Avoid complex objects unless necessary

Real-World Examples

Ticket Status Board Policy Credit Purpose

1export const TicketStatus = enumOf([
2  "active",
3  "rejected",
4  "opened",
5  "inProgress",
6  "done",
7  "reviewing",
8  "feedback",
9  "completed",
10  "archived",
11] as const);

Enum Usage in Class Methods

1static getActiveTickets(tickets: LightTicket[]) {
2  return tickets.filter(t => 
3    ["active", "inProgress"].includes(t.status)
4  );
5}

Key Takeaways

Enums ensure type safety across frontend/backend
Works seamlessly with Akan.js decorator system
Provides runtime validation in addition to compile-time checks

Quick Start

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