Add a footer to an existing OpenXML spreadsheet - excel

Question

EDIT: There's a further detail I left out with my original post. The program is using a template stream rather than a concrete template for the ".Open" command. The template stream gets initialized with this code block:
public void Initialize(Stream templateStream)
{
spreadsheet = SpreadsheetDocument.Open(templateStream, true);
}
I'm still researching this, but does anyone know the implications of using a stream for the HeaderFooter object in OpenXML?
I'm new to OpenXML and still in the process of reading and learning what I can of this massive SDK. I've inherited a C# MVC.NET program that uses OpenXML to display information on an Excel spreadsheet and all of that is working, but I now need to add a footer to the same spreadsheet and I'm hitting some brick walls in my OpenXML knowledge.
I put the footer information I wanted into the spreadsheet, opened it up with the Open XML SDK Productivity Tool and found this code under <.x:oddFooter(OddFooter):
// Creates an OddFooter instance and adds its children.
public OddFooter GenerateOddFooter()
{
OddFooter oddFooter1 = new OddFooter();
oddFooter1.Text = "&L&\"Times New Roman,Regular\"Page &P of &N&C&\"Times New Roman,Regular\"Generated On: <Date/Time> Central&R&\"Times New Roman,Regular\"Report";
return oddFooter1;
}
And this code one level up under <>x:headerFooter(OddFooter):
// Creates an HeaderFooter instance and adds its children.
public HeaderFooter GenerateHeaderFooter()
{
HeaderFooter headerFooter1 = new HeaderFooter();
OddFooter oddFooter1 = new OddFooter();
oddFooter1.Text = "&L&\"Times New Roman,Regular\"Page &P of &N&C&\"Times New Roman,Regular\"Generated On: <Date/Time> Central&R&\"Times New Roman,Regular\"Report";
headerFooter1.Append(oddFooter1);
return headerFooter1;
}
Now I of course need to append the footer info somewhere, and this is where I'm stuck. In <>x:worksheet(Worksheet) I see this line of code:
worksheet1.Append(headerFooter1);
This looked easy enough, but when I looked back at the application code I found no worksheet object to append to. I thought I was close with the following line of code:
spreadsheet.WorkbookPart.Workbook.Append(headerFooter1);
but this yielded nothing. In the application I see a SpreadsheetDocument object and references to OpenXMLParts... do I need to get a spreadsheet part to append to? Or do I need to take a different approach with a Spreadsheet versus a worksheet object? Do I need to materialize the current worksheet and then append?
I have a feeling this has an easy solution, but as I said I'm still learning the SDK.
Thank you!

Answer 1

For those who don't know about the productivity tool, it is included with the SDK and can be downloaded from https://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=5124
On my 64 bit machine, the install path to the tool was:
"C:\Program Files (x86)\Open XML SDK\V2.0\tool\OpenXmlSdkTool.exe"
You should be able to manually add a footer to a spreadsheet, and open it up with the tool and see the exact C# required to create the entire spreadsheet, including the footer. You can then remove the parts of the code that are unnecessary, like some of the styles that are automatically added.