RouteParamMetadata

Kind: Interface

Source: packages/common/decorators/http/route-params.decorator.ts

Part of: Common

RouteParamMetadata describes metadata for a parameter in an HTTP route handler. It records the parameter’s zero-based position (index) and associated route parameter configuration (data) so the framework can resolve and inject request values into the correct handler argument.

Properties

Diagram

mermaid
graph LR
  Decorator[Route parameter decorator] --> Metadata[RouteParamMetadata]
  Metadata --> Index[index: parameter position]
  Metadata --> Data[data: ParamData]
  Metadata --> Resolver[Route argument resolver]
  Resolver --> Handler[Controller handler argument]

Usage

ts
import type { RouteParamMetadata } from './route-params.decorator';

const userIdParameter: RouteParamMetadata = {
  index: 0,
  data: 'id',
};

// Used by route metadata processing to inject req.params.id
// into the first controller method argument.

AI Coding Instructions

• Keep index aligned with the decorated method parameter’s zero-based position.
• Use data values compatible with the ParamData type; do not introduce untyped parameter keys.
• Preserve this metadata shape when extending route parameter decorators, since argument resolvers depend on it.
• Avoid changing property names or semantics without updating metadata readers and request-argument resolution logic.

How it works

RouteParamMetadata is an exported TypeScript interface for an entry in HTTP route-argument metadata. Its declared shape has:

• index: number — the zero-based route-handler argument position. [packages/common/decorators/http/route-params.decorator.ts:25-28]
• data?: ParamData — optional decorator data, where ParamData is object | string | number. [packages/common/decorators/http/route-params.decorator.ts:24-28]

Standard route-parameter decorators read existing ROUTE_ARGS_METADATA, add an entry keyed as ${paramtype}:${index}, and write the resulting object back through Reflect.defineMetadata. The entry records index, data, and a pipes array. [packages/common/decorators/http/route-params.decorator.ts:47-64] The ROUTE_ARGS_METADATA metadata key is the string __routeArguments__. [packages/common/constants.ts:18]

Although pipes is stored and later read, it is not declared in RouteParamMetadata. [packages/common/decorators/http/route-params.decorator.ts:25-28] [packages/common/decorators/http/route-params.decorator.ts:37-44] Custom parameter decorators similarly create entries with index, factory, data, and pipes; factory is also not declared by the interface. [packages/common/utils/assign-custom-metadata.util.ts:9-25]

At HTTP handler setup, the router reads these entries, uses the largest recorded index plus one as the argument-array length, and converts each metadata entry into parameter-processing details. [packages/core/router/router-execution-context.ts:191-221] [packages/core/helpers/context-utils.ts:52-56] For standard entries, it passes data and the parameter type to RouteParamsFactory; for example, data selects a body, path, query, host, or header property when it is truthy. [packages/core/router/router-execution-context.ts:315-327] [packages/core/router/route-params-factory.ts:21-44] During invocation, the extracted value is written to args[index]; pipeable parameter types run global and parameter pipes first. [packages/core/router/router-execution-context.ts:392-415]

The interface itself has no runtime validation, executable behavior, thrown errors, or side effects; those occur in the decorators and router code that create and consume objects shaped like it. [packages/common/decorators/http/route-params.decorator.ts:25-28]

Used by

1 reference from 1 file. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (1)

• ParamProperties — packages/core/router/router-execution-context.ts:50