1. In Visual Studio Code, open the televisionShow folder that you extracted from ch9-start.zip and have been working with in the previous recipes of this chapter.
2. In Explorer, select src/table/Television Show.al.
3. Add the ObsoleteState and ObsoleteReason properties to the Status field, as follows:

field(4; Status; Option)
{
     OptionCaption = 'Active,Finished';
     OptionMembers = Active,Finished;
     DataClassification = CustomerContent;
     ObsoleteState = Pending;
     ObsoleteReason = 'Replaced by new field: Running';
 }

4. Add a new field to the Television Show table object:

field(9; Running; Boolean)
{
     DataClassification = CustomerContent;
}

5. Right-click on the src/codeunit folder and create a new file named App Upgrade.al. Then, create a new codeunit object:

codeunit 50112 "App Upgrade"
{

}

6. Add the Subtype = Upgrade attribute to the codeunit object:

codeunit 50112 "App Upgrade"
{
   Subtype = Upgrade;

}

This will cause the codeunit object to be executed when the application is upgraded from a previous version.

7. Add the following trigger and logic to the codeunit object:

trigger OnUpgradePerCompany()
var
     CurrentAppInfo: ModuleInfo;
begin
     if NavApp.GetCurrentModuleInfo(CurrentAppInfo) then begin
          Case CurrentAppInfo.DataVersion() of
               Version.Create('1.0.0.0'):
                    PopulateTelevisionShowRunningField();
          end;
     end;
end;

When the application is installed, if version 1.0.0.0 was previously installed, then the upgrade logic will execute in order to populate the new field.

8. Add the following logic to update the new Running field. We'll set the new field to true, but only if the Status field is set to Active:

local procedure PopulateTelevisionShowRunningField()
var
     TelevisionShow: Record "Television Show";
begin
     if TelevisionShow.FindSet() then
          repeat
               if TelevisionShow.Status = 
               TelevisionShow.Status::Active then begin
                    TelevisionShow.Running := true;
                    TelevisionShow.Modify();
               end;
          until TelevisionShow.Next() = 0;
end;

9. In Explorer, select app.json.
10. Increase the version of the application by setting the "version" property, like this:

"version": "1.1.0.0"

Now, when the application is built, it will have the new version number.

Keep working through this chapter and you'll see the upgrade code in action!