Constant

@tsed/di

Usage

import { Constant } from "@tsed/di";

See /packages/di/src/common/decorators/constant.ts.

Overview

function Constant<Type = unknown>(expression: string, defaultValue?: Type): PropertyDecorator;

• expression (string): Dot-notation path to the configuration value

• defaultValue (Type): Optional. default value if not found

Description

Inject a frozen configuration value into a property.

Retrieves a value from the injector configuration and freezes it (creates an immutable deep clone). The value is lazily loaded on first access and cached for subsequent accesses.

Usage

import {Injectable, Constant} from "@tsed/di";
import {Env} from "@tsed/core";

@Injectable()
export class MyService {
  @Constant("env")
  env: Env;

  @Constant("api.baseUrl")
  apiUrl: string;

  @Constant("api.timeout", 5000)
  timeout: number;

  constructor() {
    // Not available yet - undefined
  }

  $onInit() {
    console.log(this.env); // Value is available
  }
}