Office.context.document.getSelectedDataAsync() is unable to handle more than a handful of rows/columns of data before it decides that "too much data" was selected and refuses to do anything. A user should be able to click the upper-left corner of the spreadsheet, which selects all cells, and then Office.context.document.getSelectedDataAsync() should have an option that transfers the data to the app in a piecemeal fashion.
Grant, thanks for your suggestion! We really appreciate it. The API is only available for 2016+ clients for Windows and online, iPad, Mac platform and there is currently no plan to backport this to shared API mentioned in the request.
As such. we are closing this request. Please feel free to contact us anytime you’ve any feedback. We look forward to hearing from you.
Office Extensibility Team
Isaac Nichols commented
I encountered this issue as well when developing my Excel App and posted the question to the Office Forums a while back asking for help. Nobody was able to help me, but I eventually found a way to work around the issue by handling the case where the user selection included a full row and then limiting the getDataAsync to a subset of the selection to prevent the "too much data" error.
You can find more details of my work around here: http://social.msdn.microsoft.com/Forums/office/en-US/f4ecaa70-32ee-4fcb-a26b-dde9d87a53f1/getdataasync-fails-when-selection-is-an-entire-row-in-excel?forum=appsforoffice#bf165b30-ae32-41c9-9bbd-f90fbc686203