Rajeev Pentyala – Microsoft Power Platform

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”.

🙂