customization - abap badi customer_add_data: how to process user input in custom fields? -

I should know what is the process (save and display) with user input in custom fields.

My setup:
- New subscript for transaction XD .. (eg XD02)
- Using badi customer_add_data and customer_add_data_cs - Some custom fields have been added to the table, e.g. . KAA1

Transaction created a function group with dynpros for XD ..
- New customer fields are displayed in XD ..

However, in my new areas Nothing seems to be processed, processed I do not know how to continue my implementation

What I tried to do in the window:

  "wokrs saves data input method IF_EX_CUSTOMER_ADD_DATA_CS ~ GET_DATA." SAPLZSD_FOO_CUSTOMER = My Function Group Constants: c_foo (50) VALUE '(SAPLZSD_FOO_CUSTOMER) KNA1-ZZFOO' Field-symbols: & lt; Fs & gt; Type Any ASSIGN (c_foo) TO & lt; Fs & gt; IF sy-subrc = 0. s_kna1-ZZFOO = & lt; Fs & gt; end if. Endmethod  

What I did try in PBO to display the custom field value

  "does not work, stored values ​​do not display in dynpro module status_2001 output Statistics: gf_eori type kna1-zzeori constant: c_foo (34) VALUE '(SAPMF02D) kNA1-ZZfoo' field-symbol: .. & lt; fs & gt; Specify (c_foo) & lt; FS & gt; If the SY-subrc = 0. kna1 -zzfoo =. & Lt ;. FS> endif endmodule  

and what interface customer_add_data methods do to use customer_add_data_cs The Or my dynpros have to be written in PBO / PAI?

If a new example is for example: How to see a solution: knvv-zfoo and knvv-zbar.

< P> I'm new to customizing the SAP and in general, some disputes are needed to use BADI.

The above examples were based on a post found on the Internet. My problems, I found a work and a better solution in a book.

The essence of this is:

• I use
• Two functions (Getter) to work on importing and exporting custom fores And setter)
• Assign or return its values. Customized fields in those tasks

Now, my custom fields are saved and loaded properly.