We will first create the worksheet header table, which will be a vehicle service order table:

1. Create a new table named ConWHSVehicleServiceTable.
2. Create a primary key EDT, ConWHSVehicleServiceId; this time, extend Num. Complete the Label and Help Text properties with appropriate labels.
3. Drag the EDT from Solution Explorer to the Fields node of our table, and rename it to ServiceId.
4. Complete the ServiceId field as an ID field: Mandatory = Yes, Allow Edit = No, Allow Edit On Create = Yes.
5. Complete the relation information on the EDT.
6. Create the primary key index as ServiceIdx with ServiceId as the only field.
7. Set the Clustered Index and Primary Index properties as ServiceIdx.
8. Drag the ConWHSVehicleId EDT to our table and rename it to VehicleId.
9. Make the VehicleId field mandatory. The decision to make the field editable depends on the associated logic (referential integrity) and the business requirement.
10. Create a foreign key relation for ConWHSVehicleId to ConWHSVehicleTable.VehicleId.

11. Drag the Description EDT onto our table from the Application Explorer.
12. Create a new Base Enum for the service status, as defined here:

13. Drag ConWHSVehicleServiceStatus to our table as ServiceStatus.
14. Save and drag the new Enum to our table and rename it to ServiceStatus.
15. Make the ServiceStatus field read only. Allow Edit and Allow Edit On Create should be No. Status fields should be controlled through business logic.
16. Create date EDTs ConWHSVehicleServiceDateReq 'Requested service date' and ConWHSVehicleServiceDateConf 'Confirmed service date'. The dates should extend TransDate. Label appropriately and drag to the new table.
17. Rename the fields to ServiceDateRequested and ServiceDateConfirmed.
18. Complete the table properties as shown here:

19. Create the field groups as follows:

20. Create the now usual Find and Exist methods using ServiceId as the key.
21. You can also create your own validation on the service dates.
22. Finally, we will introduce the validateWrite method. This is to enforce the requirement that only service orders at status confirmed or less can be changed; the method should be written as follows:

public boolean validateWrite() 
{ 
    boolean ret; 
    ret = super(); 
    ret = ret && this.CheckCanEdit(); 
    return ret; 
} 
public boolean CheckCanEdit() 
{ 
    If (!this.CanEdit()) 
    { 
        //Service order cannot be changed. 
        return checkFailed("@ConWHS:ConWHS33"); 
    } 
    return true; 
} 
public boolean CanEdit() 
{ 
    switch (this.ServiceStatus) 
    { 
        case ConWHSVehicleServiceStatus::None: 
        case ConWHSVehicleServiceStatus::Confirmed: 
            return true; 
    } 
    return false; 
} 

23. Finally, we will write a method that initializes the defaults from the main table record, that is, vehicle, when it is selected. Write the following method:

public void InitFromVehicleTable(ConWHSVehicleTable _vehicle) 
{ 
    this.Description = _vehicle.Description; 
} 

24. Then, override modifiedField as follows:

public void modifiedField(FieldId _fieldId) 
{ 
    super(_fieldId); 
    switch(_fieldId) 
    { 
        case fieldNum(ConWHSVehicleServiceTable,  
                      VehicleId): 
            this.InitFromVehicleTable( 
                      ConWHSVehicleTable::Find( 
                                         this.VehicleId)); 
            break; 
    } 
} 

25. Save the table and close the editor tabs.