PropertyMetadata

Kind: Interface

Source: packages/core/injector/instance-wrapper.ts

Part of: Core

PropertyMetadata describes a property-level dependency managed by the injector. It associates a property key with the InstanceWrapper that contains the dependency's registration, lifecycle, and resolved instance information. The interface is typically used when collecting metadata for property injection on a class instance.

Properties

Diagram

mermaid
graph LR
  A[Target Class Property] --> B[PropertyMetadata]
  B --> C[key: symbol | string]
  B --> D[wrapper: InstanceWrapper]
  D --> E[Provider Definition]
  D --> F[Resolved Dependency Instance]

Usage

ts
import { InstanceWrapper } from './instance-wrapper';

interface PropertyMetadata {
  key: symbol | string;
  wrapper: InstanceWrapper;
}

class Logger {
  log(message: string) {
    console.log(message);
  }
}

class UserService {
  logger!: Logger;
}

const loggerWrapper = new InstanceWrapper({
  token: Logger,
  metatype: Logger,
});

const propertyMetadata: PropertyMetadata = {
  key: 'logger',
  wrapper: loggerWrapper,
};

// Injector logic can use the metadata to assign the resolved dependency.
const userService = new UserService();
userService[propertyMetadata.key] = loggerWrapper.instance;

userService.logger.log('Property dependency injected');

AI Coding Instructions

• Use key as the exact property name or symbol defined on the target class; do not substitute the provider token unless they are intentionally the same.
• Always provide an InstanceWrapper that represents the dependency provider and its lifecycle state.
• Support both string and symbol property keys when reading or assigning injected properties.
• Keep property metadata collection separate from instance assignment; the injector should resolve the wrapper before setting the target property.
• When adding property injection behavior, preserve wrapper scope and lifecycle handling rather than directly constructing dependencies.

How it works

PropertyMetadata

PropertyMetadata is an exported TypeScript interface that records one property dependency for an InstanceWrapper. It contains:

• key: the target property name or symbol (string | symbol). [packages/core/injector/instance-wrapper.ts:50-53]
• wrapper: the InstanceWrapper for the dependency associated with that property. [packages/core/injector/instance-wrapper.ts:50-53]

It has no methods, runtime validation, or direct side effects; it is a compile-time interface whose values are stored in an InstanceWrapper’s internal metadata cache under properties. [packages/core/injector/instance-wrapper.ts:55-58]