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      • Server Functions

      Server Functions are TanStack Start's server-side RPCs. They run on the server but can be called from loaders, components, hooks, event handlers, and other server functions.

      Basic Form

      import { createServerFn } from '@tanstack/react-start'

export const getTodos = createServerFn({ method: 'GET' }).handler(async () => {
  return db.todo.findMany()
})

      Input Validation

      const createTodo = createServerFn({ method: 'POST' })
  .validator((input: { title: string }) => {
    if (!input.title.trim()) throw new Error('Title required')
    return { title: input.title.trim() }
  })
  .handler(async ({ data }) => db.todo.create({ data }))

      Use schema validation in production and never trust client input.

      GET vs POST

      MethodUse
      GETReads, no side effects, cacheable
      POSTCreate, update, delete, side effects

      Server functions are same-origin RPCs. Use Server Routes for public APIs and webhooks.

      Next Steps