Adding a Service

Services hold business logic and database queries. They are called by server functions, never directly from components.

1. Create the service

Add a new file in services/. Use named function exports, not classes:

src/services/notification.service.ts

import { db } from '#/database'
import { notifications } from '#/database/schemas/notifications'
import { eq, desc } from 'drizzle-orm'

export async function getNotifications(userId: string) {
  return db
    .select()
    .from(notifications)
    .where(eq(notifications.userId, userId))
    .orderBy(desc(notifications.createdAt))
}

export async function markAsRead(notificationId: string) {
  return db
    .update(notifications)
    .set({ readAt: new Date() })
    .where(eq(notifications.id, notificationId))
}

2. Create the server function

Wrap the service in a server function with middleware:

src/functions/notifications.ts

import { createServerFn } from '@tanstack/react-start'
import { z } from 'zod'
import { authMiddleware } from '#/middleware/auth'
import { createRateLimitMiddleware } from '#/middleware/rate-limit'
import * as notificationService from '#/services/notification.service'

const defaultRateLimit = createRateLimitMiddleware('default')

export const listNotifications = createServerFn({ method: 'GET' })
  .middleware([defaultRateLimit, authMiddleware])
  .handler(async ({ context }) => {
    return notificationService.getNotifications(context.user.id)
  })

export const markNotificationRead = createServerFn({ method: 'POST' })
  .middleware([defaultRateLimit, authMiddleware])
  .inputValidator(z.object({ id: z.string().min(1) }))
  .handler(async ({ data }) => {
    return notificationService.markAsRead(data.id)
  })

3. Use the server function in a route

Call the server function from a route loader and return its data. Components read via Route.useLoaderData(). See Adding a Page for the full pattern.

Naming conventions

Thing	Convention	Example
Service file	<domain>.service.ts	notification.service.ts
Service exports	Named functions	getNotifications, markAsRead
Server function	camelCase verb	listNotifications, markNotificationRead