Adding a drop dialog to change vehicle group

We can use a similar pattern to use a drop dialog to update data on a record, the vehicle group in this case.

To do this, the contract and update classes are nearly identical to the earlier status change logic. We are simply updating the vehicle group. The steps required for this are similar as before, except that we will use a drop dialog form instead of menu items. It is not ideal to use menu items, as vehicle groups are defined in data. It is, therefore, far more natural to select the vehicle group with a drop-down list control.

We will be following the same pattern as before, so a summary of the first part of this task is listed as follows:

  1. Create a data contract class called ConFMSVehicleGroupChangeContract, adding the [DataContractAttribute] decoration above classDeclaration.
  2. Create variables in the classDeclaration for the vehicleId and vehicleGroupId using their EDTs.
  3. Create the data member methods as we did in the vehicle status data contract class. Remember the [DataMemberAttribute] decoration.
  4. Create the construct static method as usual.
  5. Create the class that will perform the update. Following the earlier pattern, name this class ConFMSVehicleGroupChange, and use the following methods:
    • public static ConFMSVehicleGroupChange construct()
    • public ConFMSVehicleGroupChangeContract parmContract(…)
    • public static ConFMSVehicleGroupChange newFromContract(..)
    • private void updateVehicle
    • public boolean validate()
    • public void run()
    • public void runContract(…)
  6. Next, you should write a job to test this, supplying both valid and invalid data; this is more important this time because the dialog won't allow the user to enter a vehicle group that does not exist.

There is a temptation to duplicate the vehicle status classes and then modify them for the new situation. This isn't necessarily a bad idea, but it is very vitally important to ensure that every part is modified appropriately. Failure to do this is one of the biggest causes of errors. AX's helpfulness in casting between EDTs of the same base type will allow us to use a vehicle group ID to check whether a record exists in the vehicle table. It will assume that we intended to cast the types. This is another benefit of using data contracts; we will not be allowed to cast between them.

Creating a drop dialog form

The next step is to create the user interface—a drop dialog. This is done by the following steps:

  1. Right-click on the AOTs Forms node and select New from form template | DropDialog.
  2. Rename this form to ConFMSVehicleGroupChange and drag this onto your project.
  3. We do not need a data source for this; we are going to use the data contract.
  4. In the classDeclaration, we declare our contract as follows:
    public class FormRun extends ObjectRun
{
    ConFMSVehicleGroupChangeContract contract;
}
  5. We now need to construct our contract and get the vehicle ID from the caller. The element object (the instance of the form) contains an args object, which we will use to construct the contract class:
    public void init()
{
    ConFMSVehicleTable callerVehicle;
    super();
    switch(element.args().dataset())
    {
        case tableNum(ConFMSVehicleTable):
            callerVehicle = element.args().record();
            break;
    }
    if(callerVehicle.RecId == 0)
    {
        throw error("@SYS79604");
    }
    contract = ConFMSVehicleGroupChangeContract::construct();
    contract.vehicleId(callerVehicle.VehicleId);
    contract.vehicleGroupId(callerVehicle.VehicleGroupId);
}

    Note

    The this variable has a different meaning in the context of forms. It means the element or control within the form that the current method is acting on. This could be the form, a data source, a field, or a control. The element object always refers to the instance of the form. If we are in the Methods node of the form, this and element are the same thing, but it is good practice to use element regardless when we are referring to the form instance.

  6. We now need to create an edit method that acts on a data source for the vehicle group drop-down control, but unlike before, we are using the contract as our storage:
    public edit ConFMSVehicleGroupId editVehicleGroupId(
                      boolean _set,
                      ConFMSVehicleGroupId _vehicleGroupId)
{
    if (_set)
    {
        contract.vehicleGroupId(_vehicleGroupId);
    }
    return  contract.vehicleGroupId();
}
  7. Create a method that will update the vehicle and refresh the calling record. It will be called from the clicked method of the OK button, so we need to know whether the update succeeded. The code is as follows:
    public boolean updateVehicle()
{
    ConFMSVehicleGroupChange change;
    FormDataSource           callerDS;
    
    change =
       ConFMSVehicleGroupChange::newFromContract(contract);
    if(change.validate())
    {
        change.run();
        if(element.args().record().isFormDataSource())
        {
            callerDS =
               element.args().record().dataSource();
            callerDS.research(true);
            return true;
        }
    }
    Return false;
}
  8. Enter a brief instruction in the MainInstruction control. We don't really need the SupplementalInstruction, so we can delete this control.
  9. Drag the edit method onto the DialogContent group so that it is below the MainInstruction.
  10. Finally, locate the OKButton and override its clicked method.
  11. The super() method triggers several form events, one of which closes the form. We only need our updateVehicle to be called, and we need to close the form only on success, allowing the user to correct any data entry uses without having to reopen the form:
    void clicked()
{
    if(element.updateVehicle())
    {
        super();
    }
}
  12. We now need to create a menu item. We do this by dragging the saved form onto our project's Display node (which can be found under Menu items), remembering the label.

    Note

    The final step is to add this menu item to our vehicle list page. If we simply drag this onto the form, it will not create a drop dialog. It will display the form as a normal dialog, so we have to create this manually.

  13. From the ConFMSVehicleTableListPage form, go to Designs | Design | ActionPane | HomeTab | MaintainGroup.
  14. Right-click on MaintainGroup and go to New | DropDialogButton.
  15. Rename the control to ConFMSVehicleGroupChangeButton.
  16. Change the new button's MenuItemName property to ConFMSVehicleGroupChange.
  17. Feel free to look for a nice icon in Embedded resources under Tools, and adjust the button's Big, NeedsRecord, and Primary properties as required.

Finally, it is important to understand what is happening and feel comfortable with this pattern. To challenge yourself, try the preceding steps for the vehicle schedule, and consider what might happen to the existing vehicle service records.

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