Is it possible to get document id of uploaded file(a!fileUploadField()) within same interface without submitting a form?

To confirm, you'll definitely need either this plug-in (Excel Tools), or a different one (if there is any other that has this functionality, which there might not be), as this functionality is not included in OOB Appian.  Why wouldn't you want to use a plug-in, though?

Yes, I used the Excel Tools plugin.

Here's the rule expression I used:

a!localVariables(
 
 local!excel: readexcelsheet(
 excelDocument: ri!spreadsheet,
 sheetNumber: 0,
 startRow: 2
 ),
 a!forEach(
 items: local!excel.result,
 expression: {
 app_id: fv!item.values[1],
 app_name: fv!item.values[2],
 app_owner_email: fv!item.values[3],
 app_department: fv!item.values[4],
 app_division: fv!item.values[5]
 }
 )
)

Hello Rick,

I have similar requirement except I want the user to have a look at the data in excel file before writing it to DB,
So basically I want user to upload the excel file, Once that is done a read only grid will be shown having data in the excel file in that same interface below, then the user can decide to submit it or not.

I wanted to know is it possible to do that in single interface.

Thank You. 

You can do it in a single interface, but you'll need to make the user click a "submit" button between uploading the Excel file and having Appian read its contents.  My normal suggestion here would be to add a button to the form saying something like "Load excel contents" that becomes enabled after the file is uploaded, which will then submit the task and cause the process model to loop straight back to the same task again.  As far as the user is concerned, they'll still be on the same task as when they started, plus or minus one button click to "load" the Excel contents.