Question

I’ve been looking at the microsoft support page Binding for Office automation servers with Visual C# .NET to try to create an Excel Worksheet, populate it with values in a datatable, and save it to the machine.

I have an implementation that uses early-binding and simply loops through the items, but I don’t know how you would achieve this with late-binding, and I need to be able to embed the Interop types to make the application version independent in regard to MS Office.

How would I add the rows from a datatable to a new Excel Worksheet using late-binding?

Answer 1

I would recommend writing an interface and abstracting the data population step, and the excel step. That way you can have a system that implements early binding with excel to do things, and then an engine that uses this interface to populate the excel sheet. Step 2 would be to write a second implementation of the interface using Late Binding rather than early binding. Then you just substitute the second implementation for the first in your code when you create the interface.

In the code, you would only create 1 object, the interface itself. When creating it though, you can assign it as any other class/implementation that implements that interface…here’s an example from my own code:

ISpreadsheetControl SSInterface;
if (conditionCheck())
    SSInterface = new ExcelImplementer();
else
    SSInterface = new OpenOfficeImplementer();

I Only ever use the 1 object, SSInterface, when placing data or changing page settings, etc etc…whatever else I implemented…but it can do so in two different manners based on which Class I assigned to the interface at load time.

As for the specifics and details on “how to”…I find the second example in the link you provided to be very helpful indeed. Its all about Type and Invoke. The difficulty will be keeping track of what you are working with at any given time. That is one of the things that will make it harder to work with, and a good reason to extract the early binding implementation first. That way you can see all the method names you will need and their parameter lists when writing the second.

I also want to add this: The very simple and short answer to your question is “Do it exactly the same way you already are” You just change ‘how’ you are calling the method that is populating the data…and all the rest of the excel interop implementation along with it.

UPDATE

I think this might do what you are looking for, although its messy enough that I would recommend putting it (both operations actually, one can call the other) into its own separate method, somewhere.

//Get a range object that contains the cell.
Parameters = new Object[2];
Parameters[0] = iRow + 1;
Parameters[1] = iCol;
objRange_Late = objSheet_Late.GetType().InvokeMember( "Cells",
    BindingFlags.GetProperty, null, objSheet_Late, Parameters );

//Write value in cell
Parameters = new Object[1];
Parameters[0] = row[col.ColumnName];
objRange_Late.GetType().InvokeMember( "Value", BindingFlags.SetProperty, 
    null, objRange_Late, Parameters );

I have to admit, I don’t have an implementation that I can test this on right now, but according to the things I know about it, that should work. If “Cells” doesn’t work, I would also the same code with “Range”…I dont actually know if that one takes numerical input or not.

link to Cells property description (msdn)

you might also want to explore that whole system a bit, it can help you find some of the things you might be looking for.

Tested Managed to successfully create and test the above code, it works perfectly.