Validations with Service Create Expense Report

Question

Dear experts.
I have the following doubt:
In the service "Create Expense Report" ESS the system call two component different:
Application: FITE_EXPENSES
Web Dynpro Component: FITV_FPM
Window Information: FPM_WINDOW
View Information: LAYOUT_VIEW
Configuration ID: FITV_FPM_EXPENSES
This component show two buttons Start and Cancel, as is displayed in the screen attach.
And other component is
Application: FITE_EXPENSES
Web Dynpro Component: FITE_VC_PRESELECTION
Window Information: VC_WINDOW
View Information: PRESELECTION_VIEW
Configuration ID: FITE_VC_PRESELECTION
That show the information with "Available Travel Requests / Plans and a listbox with Schema Selection(National Trip and Foreign Trip). as is displayed in the screen attach.
I need do two validations and I dont know Where Can I do this validations:
1.When I select the schema National and press the button Start the system must validate that the enduser have selectioned a row of "Available Travel Requests / Plans",  if the enduser not select a row the system have that show a message saying "Please select a row". This message have that be type error.
2. What is the name of the table and the method that use SAP for get the information that is displayed in the grid "Available Travel Requests / Plans"
Thanks in advance
Regards

Answer 1

Hi Carmen,
You can add custom code, just like the one for selected row validation. It can have logic such that if a particular trip number is selected, and it has cities of a particular country, the schema, say, 'Domestic' would be chosen. To 'auto-choose' schema, bind the attribute TRIP_SCHEMA of node TRIP_SCHEMA with the value 'Domestic'.
ABAP Dynpro is a component based model. So, a typically a component is created in such a way that it can be reused at many places. The component FITE_VC_PRESELECTION is for listing already initiated trips, and is rendered in expense report. The same component might be used in other travel web dynpro applications, like FITE_REQUEST, FITE_EXPRESS_EXPENSES, etc. The component FITV_FPM uses many other components for rendering different features of travel. You can think of it as parent-child relationship.
I am attaching an old book on WDA, which I guess, I downloaded from SDN itself.
I hope I could clear you doubts.
couldn't attach the book, as the file extension is not allowed. You can search for WDA resources at SDN, SAP help, or do a simple google search for PDF.