@TypedParam

export function TypedParam(name: string): ParameterDecorator;

Drop-in replacement for @Param("name") from @nestjs/common. Identical behavior plus:

• The path parameter is coerced to the TypeScript type ("42" → 42, "true" → true, "null" → null).
• The coerced value is validated — invalid uuid, out-of-range number, malformed date, etc. become a 400 Bad Request.
• The parameter is visible to @nestia/sdk — appears in the generated SDK with the same type your handler sees.

Vanilla @Param("id") always gives you a string. @TypedParam("id") gives you exactly the type you declared.

Basic usage

import { TypedParam, TypedRoute } from "@nestia/core";
import { Controller } from "@nestjs/common";
import { tags } from "typia";
 
@Controller("articles")
export class ArticlesController {
  // Path: GET /articles/2b5e21d8-0e44-4482-bd3e-4540dee7f3d6
  // `id` is typed as `string & tags.Format<"uuid">`
  @TypedRoute.Get(":id")
  public async at(
    @TypedParam("id") id: string & tags.Format<"uuid">,
  ): Promise<IArticle> { ... }
 
  // Path: GET /articles/section/general/page/42
  // `section` is `string`, `page` is `number & tags.Type<"uint32">`
  @TypedRoute.Get("section/:section/page/:page")
  public async list(
    @TypedParam("section") section: string,
    @TypedParam("page")    page: number & tags.Type<"uint32">,
  ): Promise<IPage<IArticle>> { ... }
}

The string "42" arrives at the wire, but page in your handler is already a number. A request to /articles/section/general/page/abc returns 400 before your handler is called.

Supported parameter types

Tags layered on top (MinLength, Maximum, Pattern, etc.) work the same as on body / query types.

Path parameters are flat by definition — you cannot decode a nested object out of a single segment. If you need an object, use @TypedQuery or @TypedBody.

When to use plain @Param instead

Reach for the vanilla decorator when:

• The param is consumed by NestJS-only middleware that expects raw strings.
• You’re migrating a route piecewise and don’t want to add the dependency yet.

Vanilla params are invisible to @nestia/sdk’s generators.

Common pitfalls

Validation is on the coerced value, not the raw string. A path of /articles/abc against @TypedParam("id") id: number fails because "abc" cannot become a number — the error is coercion, not a Minimum<…> violation. The 400 response distinguishes between them.

Path-only. @TypedParam reads from path parameters (:name in the route). For querystring values use @TypedQuery; for headers, @TypedHeaders.

See also

• TypedQuery — query-string parameters, including nested DTOs.
• TypedBody — JSON request bodies.
• TypedRoute — the route decorators these parameters live on.