Allow for headers to be passed through

Author: stephenbaldwin

Route.ts

@@ -1,4 +1,5 @@
 import IMountableItem from './IMountableItem';
+import { IncomingHttpHeaders } from 'http';
 import Router from './Router';
 import { DocumentNode, parse, print, getOperationAST } from 'graphql';
 import { AxiosTransformer, AxiosInstance, AxiosRequestConfig } from 'axios';
@@ -14,6 +15,8 @@ export interface IConstructorRouteOptions {
   cacheTimeInMs?: number;
   method?: string;
 
+  passThroughHeaders?: string[];
+
   staticVariables?: {};
   defaultVariables?: {};
 }
@@ -22,6 +25,7 @@ export interface IRouteOptions {
   path?: string;
   cacheTimeInMs?: number;
   method?: string;
+  passThroughHeaders?: string[];
 
   staticVariables?: {};
   defaultVariables?: {};
@@ -90,8 +94,10 @@ export default class Route implements IMountableItem {
   private operationName!: string;
   private operationVariables!: IOperationVariable[];
 
-  private transformRequestFn?: AxiosTransformer;
-  private transformResponseFn?: AxiosTransformer;
+  private transformRequestFn: AxiosTransformer[] = [];
+  private transformResponseFn: AxiosTransformer[] = [];
+
+  private passThroughHeaders: string[] = [];
 
   private staticVariables: {} = {};
   private defaultVariables: {} = {};
@@ -124,12 +130,32 @@ export default class Route implements IMountableItem {
     this.withOptions(options);
   }
 
+  private filterHeadersForPassThrough(headers: IncomingHttpHeaders): IncomingHttpHeaders {
+    const passThroughHeaders: IncomingHttpHeaders = {};
+
+    this.passThroughHeaders.forEach(
+      (header: string) => {
+        if (headers.hasOwnProperty(header)) {
+          passThroughHeaders[header] = headers[header];
+        }
+      }
+    );
+
+    return passThroughHeaders;
+  }
+
   setRouter(router: Router): this {
     this.router = router;
 
     return this;
   }
 
+  whitelistHeaderForPassThrough(header: string): this {
+    this.passThroughHeaders.push(header);
+
+    return this
+  }
+
   at(path: string): this {
     this.path = cleanPath(path);
 
@@ -172,6 +198,7 @@ export default class Route implements IMountableItem {
       defaultVariables,
       staticVariables,
       cacheTimeInMs,
+      passThroughHeaders,
     } = options;
 
     if (path) {
@@ -182,6 +209,10 @@ export default class Route implements IMountableItem {
       this.as(httpMethod);
     }
 
+    if (passThroughHeaders) {
+      passThroughHeaders.forEach(this.whitelistHeaderForPassThrough.bind(this));
+    }
+
     if (defaultVariables) {
       this.defaultVariables = defaultVariables;
     }
@@ -246,6 +277,8 @@ export default class Route implements IMountableItem {
       const assembledVariables = this.assembleVariables(providedVariables);
       const missingVariables = this.missingVariables(assembledVariables);
 
+      const headers = this.filterHeadersForPassThrough(req.headers);
+
       if (missingVariables.length) {
         res.json({
           error: 'Missing Variables',
@@ -254,7 +287,7 @@ export default class Route implements IMountableItem {
         return;
       }
 
-      const { statusCode, body } = await this.makeRequest(assembledVariables);
+      const { statusCode, body } = await this.makeRequest(assembledVariables, headers);
 
       res
         .status(statusCode)
@@ -273,13 +306,13 @@ export default class Route implements IMountableItem {
   // areVariablesValid(variables: {}) {}
 
   transformRequest(fn: AxiosTransformer): this {
-    this.transformRequestFn = fn;
+    this.transformRequestFn.push(fn);
 
     return this;
   }
 
   transformResponse(fn: AxiosTransformer): this {
-    this.transformResponseFn = fn;
+    this.transformResponseFn.push(fn);
 
     return this;
   }
@@ -329,7 +362,7 @@ export default class Route implements IMountableItem {
       );
   }
 
-  private async makeRequest(variables: {}): Promise<IResponse> {
+private async makeRequest(variables: {}, headers: {} = {}): Promise<IResponse> {
     const { axios, schema, operationName } = this;
 
     const config: AxiosRequestConfig = {
@@ -338,15 +371,12 @@ export default class Route implements IMountableItem {
         variables,
         operationName,
       },
-    };
 
-    if (this.transformRequestFn) {
-      config.transformRequest = this.transformRequestFn;
-    }
+      headers,
 
-    if (this.transformResponseFn) {
-      config.transformResponse = this.transformResponseFn;
-    }
+      transformRequest: this.transformRequestFn,
+      transformResponse: this.transformResponseFn,
+    };
 
     try {
       const { data, status } = await axios(config);

Router.ts

@@ -13,6 +13,7 @@ interface IGlobalConfiguration {
   autoDiscoverEndpoints?: boolean;
   optimizeQueryRequest?: boolean;
   headers?: {};
+  passThroughHeaders?: string[];
   auth?: AxiosBasicCredentials;
   proxy?: AxiosProxyConfig;
 }
@@ -35,13 +36,15 @@ export default class Router {
   public routes: Route[] = [];
   public modules: IMountableItem[] = [];
 
+  private passThroughHeaders: string[] = [];
   private axios: AxiosInstance;
 
   constructor(public endpoint: string, schema: string, assignedConfiguration?: IGlobalConfiguration) {
     const {
       auth,
       proxy,
       defaultTimeoutInMs: timeout,
+      passThroughHeaders,
       ...options
     } = {
       ...DEFAULT_CONFIGURATION,
@@ -66,6 +69,11 @@ export default class Router {
 
     this.schema = parse(schema);
     this.axios = axios.create(axiosConfig);
+
+    if (passThroughHeaders) {
+      this.passThroughHeaders = passThroughHeaders;
+    }
+
     this.options = options;
   }
 
@@ -84,20 +92,26 @@ export default class Router {
     return schema;
   }
 
-  mount(operationName: string, options?: {}): Route;
-  mount(mountableItem: IMountableItem, options?: {}): IMountableItem;
-  mount(operationNameOrMountableItem: string | IMountableItem, options?: {}): IMountableItem {
+  mount(operationName: string, options?: any): Route;
+  mount(mountableItem: IMountableItem, options?: any): IMountableItem;
+  mount(operationNameOrMountableItem: string | IMountableItem, options?: any): IMountableItem {
     if (typeof operationNameOrMountableItem === 'string') {
       const { schema, axios } = this;
       const operationName = operationNameOrMountableItem;
 
+      const passThroughHeaders = Boolean(options)
+        ? [...this.passThroughHeaders, ...options.passThroughHeaders]
+        : [...this.passThroughHeaders];
+
       const routeOptions: IConstructorRouteOptions = {
-        operationName: operationNameOrMountableItem,
+        ...options,
+
+        operationName,
 
         axios,
         schema,
 
-        ...options,
+        passThroughHeaders,
       };
 
       const graphQLRoute = new Route(routeOptions, this);