ParamProperties

Kind: Interface

Source: packages/core/helpers/context-utils.ts

Part of: Core

ParamProperties describes the metadata required to resolve a handler or controller parameter at runtime. It identifies the parameter position, its declared type, extraction configuration, optional transformation pipes, and the extractor responsible for obtaining the raw value.

Properties

Diagram

mermaid
graph LR
  A[Incoming request/context] --> B[IExtractor]
  B --> C[Extracted value]
  C --> D[PipeTransform[]]
  D --> E[Resolved parameter value]
  E --> F[Handler argument at index]
  
  G[ParamProperties] --> H[index: number]
  G --> I[type: T | string]
  G --> J[data: ParamData]
  G --> K[pipes: PipeTransform[]]
  G --> L[extractValue: IExtractor]

Usage

ts
import type { ParamProperties } from './context-utils';

const userIdParam: ParamProperties<string> = {
  index: 0,
  type: String,
  data: {
    name: 'id',
    source: 'params',
  },
  pipes: [parseIntPipe],
  extractValue: {
    extract(context, data) {
      return context.params[data.name];
    },
  },
};

// Runtime parameter resolution flow:
const rawValue = userIdParam.extractValue.extract(context, userIdParam.data);
const value = userIdParam.pipes.reduce(
  (result, pipe) => pipe.transform(result),
  rawValue,
);

handlerArguments[userIdParam.index] = value;

AI Coding Instructions

• Use index as the authoritative position when assigning the resolved value into a handler argument array.
• Keep extractValue focused on reading raw values from the current execution context; apply validation and conversion through pipes.
• Preserve pipe order, since each PipeTransform should receive the output of the previous pipe.
• Use data to pass extractor-specific configuration such as parameter names, headers, query keys, or request-body paths.
• Support both constructor types and string-based types in type, especially when runtime type metadata may be unavailable.

Relationships

• IMPORTS → ParamData
• IMPORTS → PARAMTYPES_METADATA
• IMPORTS → RESPONSE_PASSTHROUGH_METADATA
• IMPORTS → ContextType
• IMPORTS → Controller
• IMPORTS → PipeTransform
• IMPORTS → Type
• IMPORTS → isFunction