Create and Expose Core Data Services Based on a Database Table

Specify the sql view name in the view definition as ZV_BOOKING_XXX.

Specify your data source after the select from statement as ztbooking_xxx.

Specify your data definition as shown below. The keyword key is used to specific a key element and the keyword as is used to define alias names. The two associations I_Country and I_Currency are defined and exposed in the projection. The element CurrencyCode is specified as currency key for the element Cost which is an amount field. The view entity is specified as searchable using the view annotation @Search.searchable: true and the element CustomerName is specified as default search element using the element annotation @Search.defaultSearchElement: true.

@AbapCatalog.sqlViewName: 'ZV_BOOKING_XXX'
@AbapCatalog.compiler.compareFilter : true
@AbapCatalog.preserveKey: true
@AccessControl.authorizationCheck: #CHECK
@EndUserText.label : 'Data Definition Booking'
@Search.searchable : true
define view ZI_BOOKING_XXX
   as select from ztbooking_xxx as Booking
   association [0..1] to I_Country  as _Country  on $projection.country = _Country.country
   association [0..1] to I_Currency as _Currency on $projection.CurrencyCode = _Currency.Currency

   {
     key booking              as Booking,
         @Search.defaultSearchElement: true
         customername         as CustomerName,
         numberofpassengers   as NumberOfPassengers,
         emailaddress         as EmailAddress,
         country,
         dateofbooking        as DateOfBooking,
         dateoftravel         as DateOfTravel,
         @Semantics.amount.currencyCode: 'CurrencyCode'
         cost,
         @Semantics.currencyCode: true
         currencycode          as CurrencyCode,
         lastchangedat         as LastChangedAt,

         _Country,
         _Currency       
}

Go back to the data definition and used the @UI annotations to add the UI-specific semantics. Add following UI annotation in front of your data definition.

    @UI: {
  headerInfo: {
  typeName: 'Booking',
  typeNamePlural: 'Bookings',
  title: { type: #STANDARD, value: 'Booking' }
  }
}

Replace your code with following:

define view ZI_Booking_XXX
  as select from ztbooking_xxx as Booking
  association [0..1] to I_Country  as _Country  on $projection.country = _Country.Country
  association [0..1] to I_Currency as _Currency on $projection.CurrencyCode = _Currency.Currency
{

      @UI.facet: [
        {
          id:       'Booking',
          purpose:  #STANDARD,
          type:     #IDENTIFICATION_REFERENCE,
          label:    'Booking',
          position: 10 }
      ]


      @UI: {
          lineItem: [ { position: 10, importance: #HIGH, label: 'Booking ID' } ],
          identification:[ { position: 10, label: 'Booking ID' } ]
          }
  key booking                                as Booking,

      @UI: {
        lineItem: [ { position: 20, label: 'Customer', importance: #HIGH } ],
        identification:[ { position: 10, label: 'Customer' } ]
      }
      @Search.defaultSearchElement: true
      customername                           as CustomerName,

      @UI: {
      lineItem: [ { position: 30, label: 'No of Passengers', importance: #HIGH } ],
      identification:[ { position: 30, label: 'No of Passengers' } ]
      }
      numberofpassengers                     as NumberOfPassengers,

      @UI: {
           identification:[ { position: 40, label: 'Email' } ]
       }
      emailaddress                           as EmailAddress,

      @UI: {
           identification:[ { position: 50, label: 'Country' } ]
       }
      country,

      @UI: {
           identification:[ { position: 60, label: 'Booked On' } ]
       }
      dateofbooking                          as DateOfBooking,

      @UI: {   identification:[ { position: 70, label: 'Traveling on' } ]    }
      dateoftravel                           as DateOfTravel,


      @UI: {
      lineItem: [ { position: 40, label: 'Cost', importance: #HIGH } ],
      identification:[ { position: 80, label: 'Cost' } ]
      }
      @Semantics.amount.currencyCode: 'CurrencyCode'
      cost,

      @UI: { identification:[ { position: 90, label: 'Currency' } ]     }
      @Semantics.currencyCode: true
      currencycode                           as CurrencyCode,

      @UI: { identification:[ { position: 100, label: 'Last Changed At' } ] }
      lastchangedat                          as LastChangedAt,

      //publich associations
      _Country,
      _Currency
}

Save and activate your data definition.

Expose the ZI_Booking_XXX and the I_Country view entities.

  @EndUserText.label: 'Service Definition for Booking'

  define service Z_I_Booking_XXX {
  expose ZI_Booking_XXX as Booking;
  expose I_Country  as Country;
  }

Save and activate your service definition.