Usage of Custom HTTP Client & Pipeline Policies

The following sample code shows the usage of custom HTTP Client and also custom pipeline policies as Middleware

import {
  createHttpHeaders,
  HttpClient,
} from "@azure/core-rest-pipeline";
import { AdditionalPropertiesClient } from ".";

async function main() {
  // Define a custom client to send the requests
  // In this example we just log the request and
  // send back a dummy response, but this could be
  // plugged into any implementation
  const customClient: HttpClient = {
    sendRequest: async request => {
      console.log(`Sending a ${request.method} request to ${request.url}`);
      return {
        headers: createHttpHeaders(),
        bodyAsText: `{"foo": "bar"}`,
        status: 200,
        request
      };
    }
  };

  // Pass the custom HttpClient to the generated client
  const client = new AdditionalPropertiesClient({
    httpClient: customClient
  });

  // You can also use pipelines as middleware
  client.pipeline.addPolicy({
    name: "customPolicy",
    sendRequest: async (request, next) => {
      // You can manipulate the request before handing it off to the pipeline and eventually
      // get sent.
      request.headers.set("test-header", "hello world!");
      // Handing it off to the pipeline to process all remaining policies and eventually
      // reach the sendRequest on the HttpClient that we defined above (or the default if no custom HttpClient is provided)
      const response = await next(request);

      // You can also manipulate the response before handing it back to the pipeline and eventually reaching your client's method
      const parsedBody = JSON.parse(response.bodyAsText ?? "{}");
      parsedBody.testValue = "Added this is a pipeline policy!";
      response.bodyAsText = JSON.stringify(parsedBody);

      // And off the response to the pipeline
      return response;
    }
  });

  const result = await client.pets.createAPInProperties({ id: 1, name: "Foo" });

  console.log(result);
  // Output:
  // Sending a PUT request to http://localhost:3000/additionalProperties/in/properties
  // { foo: 'bar' }
}

main();