# GuardsContextCreator

**Kind:** Class

**Source:** [`packages/core/guards/guards-context-creator.ts`](https://github.com/nestjs/nest/blob/master/packages/core/guards/guards-context-creator.ts#L12)

**Part of:** [Core](subsystem-packages-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

| Method | Signature | Returns |
|---|---|---|
| `create` | `create(instance: Controller, callback: (...args: unknown[]) => unknown, module: string, contextId: undefined, inquirerId: string)` | `CanActivate[]` |
| `createConcreteContext` | `createConcreteContext(metadata: T, contextId: undefined, inquirerId: string)` | `R` |
| `getGuardInstance` | `getGuardInstance(metatype: Function | CanActivate, contextId: undefined, inquirerId: string)` | `CanActivate | null` |
| `getInstanceByMetatype` | `getInstanceByMetatype(metatype: Type<unknown>)` | `InstanceWrapper | undefined` |
| `getGlobalMetadata` | `getGlobalMetadata(contextId: undefined, inquirerId: string)` | `T` |

## 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