Using Office 365 SharePoint REST API within Rails app, access token fails

Question

I'm trying to use an Office 365 organizational SharePoint site as a storage point through the SharePoint REST API for docx files generated in a Rails app. I've registered the app through https://<domain>.sharepoint.com/_layouts/15/appregnex.aspx and obtained a client_id and client_secret. Using https://<domain>.sharepoint.com/_layouts/15/appinv.aspx, I gave the app the following permissions:

<AppPermissionRequests AllowAppOnlyPolicy="true">
  <AppPermissionRequest Scope="http://sharepoint/content/sitecollection" Right="FullControl" />
</AppPermissionRequests>

Using the oauth2 gem, I've so far managed to obtain an access token using client_credentials:

client = OAuth2::Client.new(<client_id>, <client_secret>, site: "https://<domain>.sharepoint.com", token_url: "https://login.windows.net/<tenant_id>/oauth2/token")
token = client.get_token(grant_type: "client_credentials", client_id: client.id, client_secret: client.secret, resource: "https://<domain>.sharepoint.com")

The client_credentials strategy seems to work, as a token is received. However, trying to use it results in failure.

token.get("/_api/web/title") returns OAuth2::Error: { "error_description" : "The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the <serviceDebug> configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework SDK documentation and inspect the server trace logs." }

RestClient.get("https://<domain>.sharepoint.com/_api/web/title", { "Authorization" => token.token }) returns RestClient::Unauthorized: 401 Unauthorized

I'm pretty much at my wits' end over this, and I'm this close to telling my boss that if it can somehow be done, I'm simply not knowledgeable enough to do it.

Ross Bush Ross Bush · Accepted Answer · 2014-06-28T20:19:52

The IncludeExceptionDetailInFaults is a wcf service setting in the endpoint applications web.config. If you have access to the server https://.sharepoint.com then you can turn that on momentarily. Basically, this will send the exception trace dump to the client in the response. By default, any 500 status errors will come back with no information except for ...ooops an error occurred.

I don't know how that server is configured or that much about SharePoint at all. However, the error could be anything imaginable and not even related to oauth. Unless you can get the server log or have it spit back the exception then you are going to be spinning your wheels.

Using Office 365 SharePoint REST API within Rails app, access token fails

2 Answers