GuardsContextCreator

Kind: Class

Source: packages/core/guards/guards-context-creator.ts

Part of: Core

GuardsContextCreator resolves the guards that apply to a controller handler, including method/class metadata and globally registered guards. It converts guard classes or instances into executable CanActivate instances while respecting module scope, request context, and dependency injection.

Extends: ContextCreator

Methods

Where it refuses work

• GuardsContextCreator stops the work with an early return when isEmpty(metadata).
• GuardsContextCreator stops the work with an early return when isObject.
• GuardsContextCreator stops the work with an early return when !instanceWrapper.
• GuardsContextCreator stops the work with an early return when !this.moduleContext.
• GuardsContextCreator stops the work with an early return when !moduleRef.
• GuardsContextCreator stops the work with an early return when !this.config.

Diagram

mermaid
graph LR
  A[Controller handler] --> B[GuardsContextCreator.create]
  B --> C[Read @UseGuards metadata]
  B --> D[Read global guard metadata]
  C --> E[createConcreteContext]
  D --> E
  E --> F[getGuardInstance]
  F --> G[Resolve injectable from module container]
  G --> H[CanActivate[]]

Usage

ts
import { ApplicationConfig } from '@nestjs/core/application-config';
import { GuardsContextCreator } from '@nestjs/core/guards/guards-context-creator';
import { NestContainer } from '@nestjs/core/injector/container';

const container = new NestContainer();
const applicationConfig = new ApplicationConfig();

const guardsContextCreator = new GuardsContextCreator(
  container,
  applicationConfig,
);

// `moduleToken` should identify the module that owns the controller.
const guards = guardsContextCreator.create(
  usersController,
  usersController.findAll,
  moduleToken,
);

for (const guard of guards) {
  const allowed = await guard.canActivate(executionContext);

  if (!allowed) {
    throw new Error('Request denied by guard');
  }
}

AI Coding Instructions

• Use create() when resolving guards for a controller method; it combines handler, controller, and global guard metadata.
• Ensure the supplied module token matches the module containing guard providers, or class-based guards cannot be resolved from the container.
• Guard metadata may contain either guard instances or injectable guard classes; preserve support for both when extending resolution logic.
• Pass the correct request contextId and inquirerId for request-scoped guards instead of always relying on the static context.
• Treat this as core framework infrastructure; application code should normally configure guards with @UseGuards() or global guard registration rather than instantiate this class directly.

Relationships

• IMPORTS → CanActivate
• IMPORTS → GUARDS_METADATA
• IMPORTS → Controller
• IMPORTS → Type
• IMPORTS → isEmpty
• IMPORTS → isFunction

Used by

4 references from 4 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

Imported by (4)

• RpcHandlerMetadata — packages/microservices/context/rpc-context-creator.ts:35
• MicroservicesModule — packages/microservices/microservices-module.ts:23
• WsHandlerMetadata — packages/websockets/context/ws-context-creator.ts:34
• SocketModule — packages/websockets/socket-module.ts:27