I have searched and searched and find it odd that I am unable to locate any reasonably comprehensive source code examples, on the intuit developer platform or anywhere else, to see how the .NET v3 SDK for QBO is used in a best-practices sense. Anyone know the existence of ANY kind of examples that would be helpful?
You can have a look at this link.
From the following thread, you'll get a invoice create example. how to add invoice or sales receipt quickbooks rest api v3.0
Hope it will be useful.
Thanks