how to deal with th Odata with update operation with XSJS exit ?

Dear friends,

        I am trying to write an odata with update operation and xsjs exit to update DB table from my UI5 webpage input. But I am not quick understand the the procedure. how to pass the input value to xsjs file, and how to write the odata file and the xsjs file, so any friends have some complete demo of this exercise ?  or have some advice about this part, thank you so much !

my controller code:

get the input form ui then use the omodel.update to do this

my odata file:

in my xsjs file, I want to use the input saleorderno to check whether it is exit in my DB table, if exit then update it, if not, just give the error message. I know how to do this part, but my biggest problem is how to get the input in xsjs file , how to finish this update operation.

Thanks for your sincerely answer!

Best Regards

Zhang