tbf/Results/Entities/helpers/DatabaseMigrationHelper.cs

using System;
using Common;
using log4net;
using MySql.Data.MySqlClient;

namespace Results.Entities.helpers
{
    /// <summary>
    /// Applies explicit, backwards-compatible results DB migrations before the
    /// first NHibernate session factory is created.
    /// </summary>
    public static class DatabaseMigrationHelper
    {
        private static readonly ILog log = LogManager.GetLogger(typeof(DatabaseMigrationHelper));

        public static void EnsureSchema(DBType dbType, string connectionString)
        {
            switch (dbType)
            {
                case DBType.MySql:
                    EnsureMySqlSchema(connectionString);
                    break;
                case DBType.SQLite:
                    EnsureSQLiteSchema(connectionString);
                    break;
            }
        }

        private static void EnsureMySqlSchema(string connectionString)
        {
            using (var conn = new MySqlConnection(connectionString))
            {
                conn.Open();

                // Added by newer MeterTestRslt mapping; older customer DBs do
                // not contain it and otherwise reject the entire batch insert.
                EnsureColumnMySql(conn, "MeterTestRslt", "PulsesPerKilogram", "DOUBLE NOT NULL DEFAULT 0");
                EnsureColumnMySql(conn, "MeterTestRslt", "FlipMode", "INT NULL");
                EnsureColumnMySql(conn, "MeterTestRslt", "ExtraDataPath", "VARCHAR(255) NULL");
                EnsureMeterTestResultExtraColumnsMySql(conn);
            }
        }

        private static void EnsureMeterTestResultExtraColumnsMySql(MySqlConnection conn)
        {
            for (int index = 1; index <= 9; index++)
            {
                EnsureColumnMySql(conn, "MeterTestRslt", "X" + index, "FLOAT NOT NULL DEFAULT 0");
            }
        }

        private static void EnsureColumnMySql(
            MySqlConnection conn,
            string tableName,
            string columnName,
            string columnDefinition)
        {
            using (var transaction = conn.BeginTransaction())
            {
                try
                {
                    bool exists;
                    using (var cmd = conn.CreateCommand())
                    {
                        cmd.Transaction = transaction;
                        cmd.CommandText = @"
                            SELECT COUNT(*)
                            FROM INFORMATION_SCHEMA.COLUMNS
                            WHERE TABLE_SCHEMA = DATABASE()
                              AND TABLE_NAME = @tableName
                              AND COLUMN_NAME = @columnName";
                        cmd.Parameters.AddWithValue("@tableName", tableName);
                        cmd.Parameters.AddWithValue("@columnName", columnName);
                        exists = Convert.ToInt32(cmd.ExecuteScalar()) > 0;
                    }

                    if (!exists)
                    {
                        using (var alter = conn.CreateCommand())
                        {
                            alter.Transaction = transaction;
                            alter.CommandText = "ALTER TABLE `" + tableName + "` ADD COLUMN `" +
                                                columnName + "` " + columnDefinition;
                            alter.ExecuteNonQuery();
                            log.WarnFormat("Results DB migration: added {0}.{1} ({2}).",
                                tableName, columnName, columnDefinition);
                        }
                    }

                    transaction.Commit();
                }
                catch
                {
                    transaction.Rollback();
                    throw;
                }
            }
        }

        private static void EnsureSQLiteSchema(string databaseFile)
        {
            using (var conn = new System.Data.SQLite.SQLiteConnection("Data Source=" + databaseFile))
            {
                conn.Open();

                EnsureColumnSQLite(conn, "MeterTestRslt", "PulsesPerKilogram", "REAL NOT NULL DEFAULT 0");
                EnsureColumnSQLite(conn, "MeterTestRslt", "FlipMode", "INTEGER NULL");
                EnsureColumnSQLite(conn, "MeterTestRslt", "ExtraDataPath", "TEXT NULL");
                EnsureMeterTestResultExtraColumnsSQLite(conn);
            }
        }

        private static void EnsureMeterTestResultExtraColumnsSQLite(System.Data.SQLite.SQLiteConnection conn)
        {
            for (int index = 1; index <= 9; index++)
            {
                EnsureColumnSQLite(conn, "MeterTestRslt", "X" + index, "REAL NOT NULL DEFAULT 0");
            }
        }

        private static void EnsureColumnSQLite(
            System.Data.SQLite.SQLiteConnection conn,
            string tableName,
            string columnName,
            string columnDefinition)
        {
            bool exists = false;
            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "PRAGMA table_info(" + tableName + ")";
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        if (string.Equals(reader["name"].ToString(), columnName,
                            StringComparison.OrdinalIgnoreCase))
                        {
                            exists = true;
                            break;
                        }
                    }
                }
            }

            if (!exists)
            {
                using (var alter = conn.CreateCommand())
                {
                    alter.CommandText = "ALTER TABLE " + tableName + " ADD COLUMN " +
                                        columnName + " " + columnDefinition;
                    alter.ExecuteNonQuery();
                    log.WarnFormat("Results DB migration: added {0}.{1} ({2}).",
                        tableName, columnName, columnDefinition);
                }
            }
        }
    }
}