Contextual middleware

Contextual Middleware is a NestJs middleware build to attach a context object to a request/reponse transaction. This context object can then be accessed from anywhere within the lifecycle of the transation to recall the held values at any time.

Getting Started

To supercharge your transaction contexts with this library you must perform the following steps.

1. Install the library npm i contextual-middleware --save
2. Add the middleware to all requests in main.ts

      export class AppModule implements NestModule {
       configure(consumer: MiddlewareConsumer) {
          consumer
          .apply(
            withContext,
            appendToContext(appendTrackingHeaderToContext),
            LoggerMiddleware
          ).forRoutes({ path: '*', method: RequestMethod.ALL });
        }
      }
   

3. Configure the callback to attach custom parameters to the context. The callback takes two arguments context object and a request object and returns nothing. An example is the callback which attaches tracking data from headers to context.

   const appendHeaderToContext = (context, req) => {
     context.customHeaderOne = req.headers['x-custom-header-one'];
     context.customHeaderTwo = req.headers['x-custom-header-two'];
   };
   

4. Access the context anywhere in your request life cycle using

   const context = ctx();
   console.log(context.customHeaderOne);
   

How to contribute:

Want to contribute? Feel free to create an issue, so we can talk about the issue. Then based on that create a pull request if we feel the feature/enhancement should exist.