Controllers handle incoming HTTP requests and return responses. They are decorated with @Controller() and use HTTP method decorators to define routes.

Defining a Controller

import { Controller, Get } from "nestelia";

@Controller("/cats")
class CatController {
  @Get("/")
  findAll() {
    return [{ name: "Tom" }, { name: "Garfield" }];
  }
}

The @Controller("/cats") decorator sets the route prefix. The @Get("/") decorator maps GET /cats/ to findAll().

Registering Controllers

Controllers must be declared in a module:

@Module({
  controllers: [CatController],
  providers: [CatService],
})
class CatModule {}

Injecting Services

Use @Inject() in the constructor to access services from the DI container:

@Controller("/cats")
class CatController {
  constructor(@Inject(CatService) private readonly catService: CatService) {}

  @Get("/")
  findAll() {
    return this.catService.findAll();
  }
}

Route Methods

nestelia provides decorators for all standard HTTP methods:

@Controller("/items")
class ItemController {
  @Get("/")       findAll() { /* ... */ }
  @Get("/:id")    findOne() { /* ... */ }
  @Post("/")      create()  { /* ... */ }
  @Put("/:id")    update()  { /* ... */ }
  @Patch("/:id")  patch()   { /* ... */ }
  @Delete("/:id") remove()  { /* ... */ }
  @Options("/")   options() { /* ... */ }
  @Head("/")      head()    { /* ... */ }
  @All("/wild")   any()     { /* ... */ }
}

Returning Responses

Controller methods can return:

• Plain objects / arrays — serialized to JSON automatically
• Strings — returned as plain text
• Promises — awaited and then serialized

@Get("/")
async findAll() {
  const users = await this.userService.findAll();
  return users; // serialized to JSON
}

Accessing Request Data

Use @Ctx() to get the full Elysia context, which provides access to all request data:

@Get("/:id")
findOne(@Ctx() ctx: any) {
  const id = ctx.params.id;
  const q = ctx.query.q;
  return this.service.findById(id);
}

For typed, validated access to body, params, and query, use the TypeBox-based decorators:

import { t } from "elysia";

@Post("/")
create(@Body(t.Object({ name: t.String() })) body: { name: string }) {
  return this.userService.create(body);
}

See Parameter Decorators for details.

Setting Status Codes

Use @HttpCode() to set a custom status code for a route:

@Post("/")
@HttpCode(201)
create(@Body(t.Object({ name: t.String() })) body: { name: string }) {
  return this.userService.create(body);
}

Or use the Elysia context for dynamic status codes:

@Post("/")
create(@Ctx() ctx: any, @Body(t.Object({ name: t.String() })) body: { name: string }) {
  ctx.set.status = 201;
  return this.userService.create(body);
}

Setting Response Headers

Use @Header() to add static response headers:

@Get("/")
@Header("Cache-Control", "no-store")
findAll() {
  return this.service.findAll();
}