BaseTaxImplementationsMigrations.cs

using Nwazet.Commerce.Models;
using Orchard.ContentManagement.MetaData;
using Orchard.Data;
using Orchard.Data.Migration;
using Orchard.Environment.Extensions;
using System;
using System.Data;

namespace Nwazet.Commerce.Migrations {
    [OrchardFeature("Nwazet.BaseTaxImplementations")]
    public class BaseTaxImplementationsMigrations : DataMigrationImpl {

        private readonly ITransactionManager _transactionManager;
        private readonly IRepository<StateOrCountryTaxPartRecord> _repository;
        public BaseTaxImplementationsMigrations(
            ITransactionManager transactionManager,
            IRepository<StateOrCountryTaxPartRecord> repository) {

            _transactionManager = transactionManager;
            _repository = repository;
        }

        public int Create() {
            // we could be calling this because we enabled the feature in the migrations for 
            // Nwazet.Taxes. In that case, we do not have to actually create the tables, because
            // those were handled there in the past.

            try {

                SchemaBuilder.CreateTable("StateOrCountryTaxPartRecord", table => table
                    .ContentPartRecord()
                    .Column<string>("State")
                    .Column<string>("Country")
                    .Column<decimal>("Rate")
                    .Column<int>("Priority")
                );

                ContentDefinitionManager.AlterTypeDefinition("StateOrCountryTax", cfg => cfg
                  .WithPart("StateOrCountryTaxPart"));

                ContentDefinitionManager.AlterTypeDefinition("ZipCodeTax", cfg => cfg
                    .WithPart("ZipCodeTaxPart"));
            } catch (Exception) {
                // The CreateTable throws an SqlException if the table already exists, so I thought
                // this could work. However, in its own handling it attempts to do _transaction.RollBack()
                // and that fails saying "Transaction not connected, or was disconnected".
            }

            return 1;
        }

    }
}

TaxMigrations.cs

using Orchard.ContentManagement.MetaData;
using Orchard.Data;
using Orchard.Data.Migration;
using Orchard.Data.Migration.Records;
using Orchard.Environment.Extensions;
using Orchard.Modules.Services;
using System.Data;

namespace Nwazet.Commerce.Migrations {
    [OrchardFeature("Nwazet.Taxes")]
    public class TaxMigrations : DataMigrationImpl {

        private readonly IRepository<DataMigrationRecord> _dataMigrationRepository;
        private readonly IModuleService _moduleService;
        private readonly ITransactionManager _transactionManager;

        public TaxMigrations(
            IRepository<DataMigrationRecord> dataMigrationRepository,
            IModuleService moduleService,
            ITransactionManager transactionManager) {

            _dataMigrationRepository = dataMigrationRepository;
            _moduleService = moduleService;
            _transactionManager = transactionManager;
        }

        public int Create() {
            // Update: we moved the StateCountryTax and ZipCodeTax implementations to a separate feature.
            // Hence we need to skip the migrations steps related to them.
            return 4; 
        }

        // UpdateFrom1() and UpdateFrom2() still here, for retrocompatibility

        public int UpdateFrom1() {
            ContentDefinitionManager.AlterTypeDefinition("ZipCodeTax", cfg => cfg
                .WithPart("ZipCodeTaxPart"));
            return 2;
        }

        public int UpdateFrom2() {
            SchemaBuilder.AlterTable("StateOrCountryTaxPartRecord", table =>
                table.AlterColumn("Rate", column =>
                    column.WithType(DbType.Decimal)));
            return 3;
        }

        public int UpdateFrom3() {
            // Everything that was done above now belongs to the Nwazet.BaseTaxImplementations feature.
            // If we are running this method, it means we are updating an old pre-territories system.
            // We need to activate the Nwazet.BaseTaxImplementations feature, and not run its migrations,
            // because those would break the db by trying to recreate tables.
            // The issue is that I don't know how to enable the feature and not run its migration.

            _moduleService.EnableFeatures(new string[] { "Nwazet.BaseTaxImplementations" }, true);

            return 4;
        }
    }
}