Rajeev Pentyala – Technical Blog on Power Platform, Azure and AI

In this article, lets see how to connect and test Dynamics 365 Web API requests using Postman tool, step by step along with troubleshooting steps.

Note: Refer article for steps to connect to Dataverse Web API from Postman tool.

Those who are not familiar with Postman tool, it is a request composer tool, which allows you to authenticate to your Dynamics 365 instance,  compose Web API requests, send them, and view response. Link to download

Prerequisites:

• Download Postman tool
• Dynamics 365 online instance. (Subscribe to 30 days trial, if you have not one)
• Azure Active Directory Portal (You need to login with your Office 365 Credentials)

Register App in Azure Active Directory:

As a first step, you need to register an App in Azure Active Directory (i.e., oAuth) by following below steps

• Connect to the Azure Active Directory (AD) Portal with your Office 365 credentials.
• Register a new Dynamics 365 App by following steps mentioned here
• Once you are done with App registration, copy ‘Application ID’ and ‘Home page’ values, which you need to use next steps.

Setup your Postman tool:

Create ‘Environment’

• Create a new Postman ‘Environment’ with below variables. This is one time activity for a single D365 instance.
  • url : Your Dynamics 365 URL
  • clientid : ‘Application ID’ from Azure AD,  generated in above section.
  • version : Dynamics version
  • webapiurl : Set this to {{url}}/api/data/v{{version}}/
  • callback : ‘Home page’ value from Azure AD,  generated in above section.
  • authurl : Set this to https://login.microsoftonline.com/common/oauth2/authorize?resource={{url}}
• I created a new ‘Environment’ with name ‘DynamicsCRM’ and it looks as below

Generate oAuth Access Token:

Post ‘Environment’ creation, we need to generate oAuth Access Token. This is one time activity for a single D365 instance.

• Make sure you select ‘Environment’ created in previous section. In my case its ‘DynamicsCRM’.
• Under ‘Authorization’ tab, set ‘Type’ to ‘oAuth 2.0’ and click on ‘Get New Access Token’.

• In the ‘GET NEW ACCESS TOKEN SCREEN’ make sure you set values as below.

• Click ‘Request Token’ and system will prompt you for credentials, pass your O365 credentials.

• When you click ‘Next’, you may encounter “response_type ‘token’ is not enabled for the application” exception.
  • To fix this, make sure in your Azure AD Application’s manifest “oauth2AllowImplicitFlow” property is set to ‘true’

• You may also encounter “The reply url specified in the request does not match the reply urls configured for the application“.
  • To fix this, make sure you set the Postman’s ‘Environment’ -> ‘callback’ variable set correctly.

• Click ‘Continue’ to complete the ‘Access Token’ generation process.
• On successful ‘Access Token’ generation, you would get the screen as below.

• Click ‘Use Token’.

That’s it! we are done with settings and its time to test the Dynamics API’s with Postman

Test by executing ‘WhoAmI’ request:

• Make sure you select the right ‘Environment’ and generated your ‘Access Token’.
• Select ‘GET’ operation and set the URL as {{webapiurl}}WhoAmI
• Click ‘Send’
• You should get “200 OK” response up on success.

• You may get “401 Unauthorized” response.

• To fix this, make sure you set “Add authorization data to” to “Request Headers”.

🙂