New: Select OAuth grant type for authentication

README.md

@@ -6,7 +6,7 @@ This a node API wrapper for accessing the Trustpilot APIs. You can learn all abo
 
 ## Installation
 
-This module is built using Typescript and Node.js `v8.10.x`.
+This module is built using Typescript and Node.js `v12.21.x`.
 
 If you are not using version 4 of Node, you'll have to transpile the code down to ES5 yourself.
 
@@ -65,6 +65,24 @@ async run() {
 }
 ```
 
+### Choose OAuth token grant type
+
+For service-to-service communication use 'client_credentials' grant type and API application key, secret combination to obtain an OAuth token. (Default grant type: password)
+
+```ts
+import { TrustpilotApi } from "trustpilot";
+
+async run() {
+  const client = await new TrustpilotApi({
+      key: 'YOUR-API-KEY',
+      secret: 'YOUR-SECRET',
+      granttype: 'client_credentials'
+    }).authenticate();
+
+  // Use client
+}
+```
+
 ### Override API Base URL
 
 The Invitations API methods have a different base URL. To override it, simply pass the `baseUrl`.

src/access-provider.ts

@@ -1,6 +1,6 @@
 import * as rp from 'request-promise-native';
 
-import { ITrustpilotApiConfig } from './models';
+import { GrantType, ITrustpilotApiConfig } from './models';
 
 export class AccessProvider {
   private apiAuthorization: any | undefined;
@@ -26,12 +26,13 @@ export class AccessProvider {
   private createApiTokenRequest() {
     const defaultRequest = {
       form: {
-        grant_type: 'password',
+        grant_type: this.trustpilotApiConfig.grantType || GrantType.password,
         password: this.trustpilotApiConfig.password,
         username: this.trustpilotApiConfig.username,
       },
       uri: '/v1/oauth/oauth-business-users-for-applications/accesstoken',
     };
+
     return (this.trustpilotApiConfig.tokenRequest) as typeof defaultRequest || defaultRequest;
   }
 

src/models.ts

@@ -10,7 +10,13 @@ interface IConfig {
   password: string;
   tokenRequest: any;
   accessToken: string;
+  grantType: GrantType;
   defaultHeaders: IHeaders;
 }
 
+export enum GrantType {
+  password = 'password',
+  client_credentials = 'client_credentials'
+}
+
 export interface ITrustpilotApiConfig extends Partial<IConfig> {}