Nest - 执行上下文

主要有两个重要的执行上下文的类:

{ host: ArgumentsHost, context: ExecutionContext }

ArgumentsHost

ArgumentsHost 类提供了用于检索传递给处理程序的参数的方法

它允许选择适当的上下文:

• host.switchToHttp: http 环境
• host.switchToRpc: RPC 微服务环境
• host.switchToWs: Websocket

使用

app context

if (host.getType() === "http") {
  // do something that is only important in the context of regular HTTP requests (REST)
} else if (host.getType() === "rpc") {
  // do something that is only important in the context of Microservice requests
} else if (host.getType<GqlContextType>() === "graphql") {
  // do something that is only important in the context of GraphQL requests
}

http Type1

const [req, res, next] = host.getArgs();

// or

const request = host.getArgByIndex(0);
const response = host.getArgByIndex(1);

http Type2

const ctx = host.switchToHttp();
const request = ctx.getRequest<Request>();
const response = ctx.getResponse<Response>();

ws/rpc

export interface WsArgumentsHost {
  /**

   * Returns the data object.
   */
  getData<T>(): T;
  /**

   * Returns the client object.
   */
  getClient<T>(): T;
}

export interface RpcArgumentsHost {
  /**

   * Returns the data object.
   */
  getData<T>(): T;

  /**

   * Returns the context object.
   */
  getContext<T>(): T;
}

ExecutionContext

ExecutionContext 提供了当前执行过程的信息:

• getClass: 控制器上下文
• getHandler: 处理函数上下文

const methodKey = ctx.getHandler().name; // "create"
const className = ctx.getClass().name; // "PersonController"

我们可以通过拿到控制器上下文和处理函数上下文来获取元数据来构建守卫 (guard) 或拦截器 (interceptors) 的逻辑