@anyit/cfg-typeorm-value-provider v1.0.5

Typeorm values provider

The TypeormValueProvider is a custom value provider for the @anyit/cfg library that fetches configuration items from a TypeORM Repository and provides them to the Cfg class.

Constructor

new TypeormValueProvider(args: TypeormValueProviderArgs)

Creates a new instance of the TypeormValueProvider.

• args.dataSource (required): The TypeORM DataSource from which to fetch the configuration items.
• args.trigger (optional): The ValueProviderTrigger that will trigger updates for this provider when configuration items change. Default is undefined.
• args.tag (optional): The tag to associate with the configuration items fetched by this provider. Default is undefined.
• args.serviceName (optional): The name of the service for which to fetch the configuration items. Default is the value of process.env.SERVICE_NAME.
• args.serviceVersion (optional): The version of the service for which to fetch the configuration items. Default is the value of process.env.CFG_SERVICE_VERSION.
• args.createMissingItems (optional): When it is true, the provider will create records in a database for every config item that is not yet stored. Default is true.

Methods

load(configItems: ConfigItem[]): Promise<void>

Loads the configuration items from the Repository based on the provided configItems array. The loaded items are then emitted through the 'loaded' event.

• configItems: An array of ConfigItem objects representing the configuration items to load.

Loading Process:

1. Unversioned Items: The method first looks for configuration items that have the serviceVersion set to null (unversioned items).
2. Versioned Items: Next, the method looks for configuration items that have the serviceVersion set to a specific value (versioned items). If the TypeormValueProvider instance was initialized with a specific serviceVersion, it will fetch these versioned items from the database based on the same condition.
3. Merging: The resulting configuration items are obtained by merging the unversioned and versioned items. Versioned items take priority over unversioned items, meaning that if a configuration item exists in both sources, the value from the versioned item will be used.

Events

Event: 'loaded' Emitted when the configuration items have been loaded from the Repository.

Usage

Before using the TypeormValueProvider, you need to ensure that the ConfigModel is registered with TypeORM. This is typically done by adding the ConfigModel to the entities array in your TypeORM configuration.

// Assuming you have a TypeORM configuration file like this:
import { ConfigModel } from './models/config-model';

export default {
  type: 'postgres',
  host: 'localhost',
  port: 5432,
  username: 'dbuser',
  password: 'dbpassword',
  database: 'dbname',
  entities: [ConfigModel, /* other entities */],
  synchronize: true,
};

Assuming you have already defined configuration in the config.ts:

export const Config = Cfg.set({
  server: {
    host: {
      default: 'localhost',
      type: 'string',
    },
    port: {
      default: 3000,
      type: 'integer',
    },
  },
});

Then you can use the TypeormValueProvider:

import { TypeormValueProvider } from '@anyit/cfg-typeorm-value-provider';
import { DataSource } from 'typeorm';
import { Config } from './config';

// Create a TypeORM DataSource and Repository
const dataSource = new DataSource(...);

// Create an instance of TypeormValueProvider
const valueProvider = new TypeormValueProvider({
  dataSource,
  tag: 'my-tag',
  serviceName: 'my-service',
  serviceVersion: '1.0.0',
});

// Load the configuration items
(async () => {
  await Config.load(valueProvider)
})()

Using triggers

You can configure when to reload configuration from TypeORM with the help of triggers. To do so, just create an instance of a trigger and pass it to the TypeormValueProvider constructor:

import { TypeormValueProvider } from '@anyit/cfg-typeorm-value-provider';
import { IntervalTrigger } from '@anyit/cfg-interval-trigger';
import { DataSource } from 'typeorm';
import { Config } from './config';

// Create a TypeORM DataSource and Repository
const dataSource = new DataSource(...);

const triggerIntervalInSeconds = 10; // Set the desired interval in seconds
const intervalTrigger = new IntervalTrigger({ interval: triggerIntervalInSeconds });

// Create an instance of TypeormValueProvider
const valueProvider = new TypeormValueProvider({
  dataSource,
  tag: 'my-tag',
  trigger: intervalTrigger,
  serviceName: 'my-service',
  serviceVersion: '1.0.0',
});