effect-store-patterns

Effect-TS Store Implementation Patterns and Best Practices

Import Patterns

Always Use Relative Paths for Internal Imports

• CRITICAL: Never use src/ aliases for internal imports
• Always use relative paths like ../schema/blog-schema.js
• Use package imports only for external dependencies
• Store files follow pattern: store-name.store.ts

// ✅ CORRECT - Relative paths for internal imports
import { BlogSchema } from '../schema/blog-schema.js'
import { ConfigService } from '../../config/config-service.js'

// ✅ CORRECT - Package imports for external dependencies
import { BlogPost, BlogPostId } from '@t6c/blog-domain'
import { Effect as E, Context } from 'effect'

// ❌ WRONG - Never use src/ aliases
import { BlogSchema } from 'src/stores/blog/schema/blog-schema.js'

Store Service Definition

Service Class Structure

export class BlogStore extends E.Service<BlogStore>()('BlogStore', {
  dependencies: [DynamoDBDocument.layer({})],
  effect: E.gen(function* () {
    const dynamodb = yield* DynamoDBService
    
    return {
      create: (blogPost: BlogPost) => E.gen(function* () {
        // Implementation
      }),
      getById: (id: BlogPostId) => E.gen(function* () {
        // Implementation  
      }),
    }
  }),
}) {
  static makeTestService = (
    mockImplementation: Partial<Omit<BlogStore, '_tag'>>,
  ) =>
    Layer.succeed(BlogStore, {
      _tag: 'BlogStore',
      create: () => E.die('Not implemented' as const),
      getById: () => E.die('Not implemented' as const),
      ...mockImplementation,
    })
}

Configuration Management

Environment Variables in config.ts

• ALWAYS store environment variables in config.ts using Effect's Config system
• Use Config.string() for regular values and Config.redacted() for sensitive data
• Provide mock configuration for testing

// config.ts
import { Config, ConfigProvider, Layer } from 'effect'

export const envVars = {
  BLOG_TABLE: Config.string('BLOG_TABLE'),
  USER_SERVICE_URL: Config.string('USER_SERVICE_URL'),
  USER_SERVICE_API_KEY: Config.redacted('USER_SERVICE_API_KEY'),
  ALGOLIA_APP_ID: Config.string('ALGOLIA_APP_ID'),
  ALGOLIA_SEARCH_API_KEY: Config.redacted('ALGOLIA_SEARCH_API_KEY'),
  ALGOLIA_WRITE_API_KEY: Config.redacted('ALGOLIA_WRITE_API_KEY'),
  OPENAI_API_KEY: Config.redacted('OPENAI_API_KEY'),
  CONTENT_BUCKET: Config.string('CONTENT_BUCKET'),
} as const

const mockConfigProvider = ConfigProvider.fromJson({
  BLOG_TABLE: 'blog-table-test',
  USER_SERVICE_URL: 'http://localhost:3000',
  USER_SERVICE_API_KEY: 'USER_SERVICE_API_KEY',
  ALGOLIA_APP_ID: 'ALGOLIA_APP_ID',
  ALGOLIA_SEARCH_API_KEY: 'ALGOLIA_SEARCH_API_KEY',
  ALGOLIA_WRITE_API_KEY: 'ALGOLIA_WRITE_API_KEY',
  OPENAI_API_KEY: 'OPENAI_API_KEY',
  CONTENT_BUCKET: 'CONTENT_BUCKET',
})

export const MockConfigLayer = Layer.setConfigProvider(mockConfigProvider)