Umbraco-CMS/src/Umbraco.Web/Install/InstallSteps/DatabaseUpgradeStep.cs

using System;
using System.Configuration;
using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Logging;
using Umbraco.Core.Migrations.Install;
using Umbraco.Web.Install.Models;

namespace Umbraco.Web.Install.InstallSteps
{
    [InstallSetupStep(InstallationType.Upgrade | InstallationType.NewInstall,
        "DatabaseUpgrade", 12, "")]
    internal class DatabaseUpgradeStep : InstallSetupStep<object>
    {
        private readonly DatabaseBuilder _databaseBuilder;
        private readonly IRuntimeState _runtime;
        private readonly ILogger _logger;

        public DatabaseUpgradeStep(DatabaseBuilder databaseBuilder, IRuntimeState runtime, ILogger logger)
        {
            _databaseBuilder = databaseBuilder;
            _runtime = runtime;
            _logger = logger;
        }

        public override InstallSetupResult Execute(object model)
        {
            var installSteps = InstallStatusTracker.GetStatus().ToArray();
            var previousStep = installSteps.Single(x => x.Name == "DatabaseInstall");
            var upgrade = previousStep.AdditionalData.ContainsKey("upgrade");

            if (upgrade)
            {
                _logger.Info<DatabaseUpgradeStep>("Running 'Upgrade' service");

                var result = _databaseBuilder.UpgradeSchemaAndData();

                if (result.Success == false)
                {
                    throw new InstallException("The database failed to upgrade. ERROR: " + result.Message);
                }

                DatabaseInstallStep.HandleConnectionStrings(_logger);
            }

            return null;
        }

        public override bool RequiresExecution(object model)
        {
            //if it's properly configured (i.e. the versions match) then no upgrade necessary
            if (_runtime.Level == RuntimeLevel.Run)
                return false;

            var installSteps = InstallStatusTracker.GetStatus().ToArray();
            //this step relies on the previous one completed - because it has stored some information we need
            if (installSteps.Any(x => x.Name == "DatabaseInstall" && x.AdditionalData.ContainsKey("upgrade")) == false)
            {
                return false;
            }

            var databaseSettings = ConfigurationManager.ConnectionStrings[Constants.System.UmbracoConnectionName];

            if (_databaseBuilder.IsConnectionStringConfigured(databaseSettings))
            {
                //Since a connection string was present we verify whether this is an upgrade or an empty db
                var result = _databaseBuilder.ValidateDatabaseSchema();

                var determinedVersion = result.DetermineInstalledVersion();
                if (determinedVersion.Equals(new Version(0, 0, 0)))
                {
                    //Fresh install
                    return false;
                }

                //Upgrade
                return true;
            }

            //no connection string configured, probably a fresh install
            return false;
        }
    }
}