External Access Sharepoint API Online

Register Add-In

• Navigate and login to SharePoint online site.
• Then navigate to the Register Add-In page by entering the url as https://<sitename>.SharePoint.com/_layouts/15/appregnew.aspx
• Click Generate button next to the Client Id and Client Secret textboxes to generate the respective values.
• Enter Add-In Title in Title textbox
• Enter AppDomian as a loclhost
• Enter RedirectUri as a https://localhost 

• 
• Click Create button, which registers the add-in and returns the success message with created information.

• 

Grant Permissions to Add-In 

• Navigate to the SharePoint site
• Then enter the URL https://<sitename>.sharepoint.com/_layouts/15/appinv.aspx in the browser. This will redirect to Grant permission page.
• Enter the Client ID(which we have generated earlier), in AppId textbox and click Lookup button. That will populate the value to other textboxes in Title, App Domain and Redirect Url
• 
• Now enter the below permission request in XML format. 
• <AppPermissionRequests AllowAppOnlyPolicy="true">     <AppPermissionRequest Scope="http://sharepoint/content/sitecollection/web" Right="Read" /></AppPermissionRequests>
• Then click Create button. This will redirect to you page, where we have to trust the add-in to read items from website.

 Retrieve the Tenant ID

•  Launch Postman chrome extension.
• Select Get Method
• Enter the below URL in the “Request URL” textbox https://<sitename>/sharepoint.com/_vti_bin/client.svc/
• Configure the below information in the header section to send along with the url requestMethod = Get
• Headers: Authorization Bearer

Generate the Access Token

• After getting the Tenant ID, we have to form a URL with the below format    https://accounts.accesscontrol.windows.net/<TenantID>/tokens/OAuth/2 for requesting the access token.
• Apply the below configurations in header
• Method = POST
• Headers
• Content-Type : application/x-www-form-urlencoded
• Body
• grant_type : client_credentials
• client_id :ClientID@TenantID
• client_secret : ClientSecret
• resource: resource/SiteDomain@TenantID               

• After applying the configuration, click Send button. That will returns the response with the Access Token.

Access the SharePoint resource

• In Postman tool, add the below URL to retrieve the web title https://<sitename>.sharepoint.com/sites/demo/_api/web/lists/getbytitle('customlist')/items

• Apply configurations in header
• Method = POST
• Accept : application/json;odata=verbose
• Authorization : Bearer ayx7fs.....
• After applying the configuration, click Send button.
• We will get the response successful as below if the permission xml applied correctly in app in the page. Otherwise, we will get the access denied error message.