As most of us, I already know my next week work schedule. It includes writing some actions in respond to a requirement for excel exports. It’s nothing new and its’s relatively easy with libraries like NPOI: you just create your excel on the fly and return a FileResult.
Read how to create an excel on the fly inside your action here: http://www.talkingdotnet.com/import-export-excel-asp-net-core-2-razor-pages/
And that could be the end of story for that requirement, but while walking home for the weekend I remembered about the XmlSerializerOutputFormatter I read on Microsoft Docs. The idea was to write my own
ExcelOutputFormatter to respond to client requests with an Excel instead of a JSON.