How can I read/write to an Excel template (.xltx) from C#?

I have ReportTemplate.xltx in my Visual Studio solution/project. How can I read and write data from my ExcelReport.DataGrid using my ReportTemplate.xltx tem开发者_开发知识库plate in my solution?

Basically I want to put the data in my datagrid into a new excel file using my report template.

How can I do that?

The Open XML SDK from Microsoft allows you to work with the XSLX files using c# without requiring Excel to be installed.

I assume it also covers XLTX files (but I haven't confirmed it myself).