feat: Add getters for headers (#111)

* Add methods to get headers from request
* Write tests for getHeader and getAllHeaders
* Update other RequestModel methods to use getHeader

Author: seb-cr

src/Service/Request.service.js

@@ -41,18 +41,47 @@ export default class RequestService extends DependencyAwareClass {
     return typeof queryParameters[parameter] !== 'undefined' ? queryParameters[parameter] : ifNull;
   }
 
+  /**
+   * Get all HTTP headers included in the request.
+   *
+   * @returns {object} An object with a key for each header.
+   */
+  getAllHeaders() {
+    return { ...this.getContainer().getEvent().headers };
+  }
+
+  /**
+   * Get an HTTP header from the request.
+   *
+   * The header name is case-insensitive.
+   *
+   * @param {string} name The name of the header.
+   * @param {string} [whenMissing] Value to return if the header is missing.
+   *   (default: empty string)
+   *
+   * @returns {string}
+   */
+  getHeader(name: string, whenMissing: string = '') {
+    const headers = this.getAllHeaders();
+    if (!headers) {
+      return whenMissing;
+    }
+    const lowerName = name.toLowerCase();
+    const key = Object.keys(headers).find((k) => k.toLowerCase() === lowerName);
+    return (key && headers[key]) || whenMissing;
+  }
+
   /**
    * Get authorization token
    * @return {*}
    */
   getAuthorizationToken() {
-    const { headers } = this.getContainer().getEvent();
-
-    if (typeof headers.Authorization === 'undefined' && typeof headers.authorization === 'undefined') {
+    const authorization = this.getHeader('Authorization');
+    if (!authorization) {
       return null;
     }
 
-    const tokenParts = headers[typeof headers.Authorization === 'undefined' ? 'authorization' : 'Authorization'].split(' ');
+    const tokenParts = authorization.split(' ');
     const tokenValue = tokenParts[1];
 
     if (!(tokenParts[0].toLowerCase() === 'bearer' && tokenValue)) {
@@ -103,30 +132,22 @@ export default class RequestService extends DependencyAwareClass {
     }
 
     if (event.httpMethod === 'POST' || requestType === REQUEST_TYPES.POST) {
+      const contentType = this.getHeader('Content-Type');
       let queryParameters = {};
 
-      if (
-        (typeof event.headers['Content-Type'] !== 'undefined' && event.headers['Content-Type'].includes('application/x-www-form-urlencoded')) ||
-        (typeof event.headers['content-type'] !== 'undefined' && event.headers['content-type'].includes('application/x-www-form-urlencoded'))
-      ) {
+      if (contentType.includes('application/x-www-form-urlencoded')) {
         queryParameters = QueryString.parse(event.body);
       }
 
-      if (
-        (typeof event.headers['Content-Type'] !== 'undefined' && event.headers['Content-Type'].includes('application/json')) ||
-        (typeof event.headers['content-type'] !== 'undefined' && event.headers['content-type'].includes('application/json'))
-      ) {
+      if (contentType.includes('application/json')) {
         try {
           queryParameters = JSON.parse(event.body);
         } catch {
           queryParameters = {};
         }
       }
 
-      if (
-        (typeof event.headers['Content-Type'] !== 'undefined' && event.headers['Content-Type'].includes('text/xml')) ||
-        (typeof event.headers['content-type'] !== 'undefined' && event.headers['content-type'].includes('text/xml'))
-      ) {
+      if (contentType.includes('text/xml')) {
         XML2JS.parseString(event.body, (error, result) => {
           if (error) {
             queryParameters = {};
@@ -135,12 +156,11 @@ export default class RequestService extends DependencyAwareClass {
           }
         });
       }
-      if (
-        (typeof event.headers['Content-Type'] !== 'undefined' && event.headers['Content-Type'].includes('multipart/form-data')) ||
-        (typeof event.headers['content-type'] !== 'undefined' && event.headers['content-type'].includes('multipart/form-data'))
-      ) {
+
+      if (contentType.includes('multipart/form-data')) {
         queryParameters = this.parseForm(true);
       }
+
       return typeof queryParameters !== 'undefined' ? queryParameters : {};
     }
 
@@ -170,19 +190,7 @@ export default class RequestService extends DependencyAwareClass {
    * @return {*}
    */
   getUserBrowserAndDevice() {
-    const { headers } = this.getContainer().getEvent();
-    let userAgent = null;
-
-    if (typeof headers !== 'object' || headers === null) {
-      return null;
-    }
-
-    Object.keys(headers).forEach((header) => {
-      if (header.toUpperCase() === 'USER-AGENT') {
-        userAgent = headers[header];
-      }
-    });
-
+    const userAgent = this.getHeader('user-agent', null);
     if (userAgent === null) {
       return null;
     }

tests/unit/Service/Request.service.test.js

@@ -210,4 +210,36 @@ describe('Service/RequestService', () => {
       });
     });
   });
+
+  describe('getAllHeaders()', () => {
+    const event = { ...getEvent };
+    const di = new DependencyInjection(CONFIGURATION, event, getContext);
+    const request = new RequestService(di);
+
+    it('should return all headers from the event', () => {
+      expect(request.getAllHeaders()).toStrictEqual(getEvent.headers);
+    });
+  });
+
+  describe('getHeader()', () => {
+    const event = { ...getEvent };
+    const di = new DependencyInjection(CONFIGURATION, event, getContext);
+    const request = new RequestService(di);
+
+    it('should return the specified header', () => {
+      expect(request.getHeader('Accept')).toEqual(event.headers.Accept);
+    });
+
+    it("should return '' by default if header is missing", () => {
+      expect(request.getHeader('Authorization')).toEqual('');
+    });
+
+    it("should return `whenMissing` if header is missing", () => {
+      expect(request.getHeader('Authorization', 'none')).toEqual('none');
+    });
+
+    it('should not be case-sensitive', () => {
+      expect(request.getHeader('accept')).toEqual(event.headers.Accept);
+    });
+  });
 });