PrimaryKey.ts

PrimaryKey.ts overview

The PrimaryKey module defines a small protocol for values that can expose a stable, string-based identifier. A value participates by implementing a method at symbol; consumers can check unknown values with isPrimaryKey and read the key with value.

Since v2.0.0

---

Exports Grouped by Category

• accessors
  • value
• models
  • PrimaryKey (interface)
  • isPrimaryKey
• symbols
  • symbol

---

accessors

value

Extracts the string value from a PrimaryKey.

When to use

Use to read the stable string identifier from a value that implements PrimaryKey.

Example (Reading primary key values)

import { PrimaryKey } from "effect"

class OrderId implements PrimaryKey.PrimaryKey {
  constructor(
    private timestamp: number,
    private sequence: number
  ) {}

  [PrimaryKey.symbol](): string {
    return `order_${this.timestamp}_${this.sequence}`
  }
}

const orderId = new OrderId(1640995200000, 1)
console.log(PrimaryKey.value(orderId)) // "order_1640995200000_1"

// Can also be used with simple string-based implementations
const simpleKey = {
  [PrimaryKey.symbol]: () => "simple-key-123"
}
console.log(PrimaryKey.value(simpleKey)) // "simple-key-123"

Signature

declare const value: (self: PrimaryKey) => string

Source

Since v2.0.0

models

PrimaryKey (interface)

An interface for objects that can provide a string-based primary key.

When to use

Use to define values that expose a stable string identifier for equality, hashing, caching, or persistence.

Details

Objects implementing this interface must provide a method that returns a unique string identifier.

Example (Implementing a primary key)

import { PrimaryKey } from "effect"

class ProductId implements PrimaryKey.PrimaryKey {
  constructor(
    private category: string,
    private id: number
  ) {}

  [PrimaryKey.symbol](): string {
    return `${this.category}-${this.id}`
  }
}

const productId = new ProductId("electronics", 42)
console.log(PrimaryKey.value(productId)) // "electronics-42"

Signature

export interface PrimaryKey {
  [symbol](): string
}

Source

Since v2.0.0

isPrimaryKey

Checks whether a value implements the PrimaryKey protocol.

When to use

Use to narrow an unknown value before treating it as a PrimaryKey.

Details

This is a structural guard for the PrimaryKey.symbol property.

Gotchas

This guard does not call the method or verify that it returns a string.

See

• PrimaryKey for the protocol being checked
• value for extracting the string value after narrowing

Signature

declare const isPrimaryKey: (u: unknown) => u is PrimaryKey

Source

Since v4.0.0

symbols

symbol

Defines the unique identifier used to identify objects that implement the PrimaryKey interface.

When to use

Use to implement the PrimaryKey protocol as a computed property key on classes or object literals that expose a stable string identifier.

See

• PrimaryKey for the protocol interface that declares the method keyed by this symbol
• value for reading the string key from a PrimaryKey value
• isPrimaryKey for checking whether an unknown value carries this method

Signature

declare const symbol: "~effect/interfaces/PrimaryKey"

Source

Since v2.0.0