Unable to fetch lookup field values using REST api

Question

I am using REST api to fetch data from a SharePoint list.

I am able to get the lookup fields data using this query: requestUri = "/_api/lists/GetByTitle('Data')/items?$select=ID,Title,Department/Title&$expand=Department .

However when I use this query requestUri = "/_api/lists/GetByTitle('Data')/items(6)" or this query requestUri = "/_api/lists/GetByTitle('Data')/items?$select=ID,Title,Department/Title&$expand=Department&$filter=ID eq 6" I am not getting the data from the lookup fields.

What could be going wrong here?

Answer 1

I tested with the endpoint, it works:

/_api/web/lists/GetByTitle('ListName')/items(1)?$select=ID,Title,Department/Title&$expand=Department

Compared the url with yours in original question, only append web behind /_api, it should be working.

Answer 2

The issue was found.

Figured out that I was fetching an item for which all the lookup fields were blank.

I fetched another item, and data was returned as expected.