private void UpdateScriptHash(string newHash, MigrationModelHashStorageMode mode)
{
if (mode == MigrationModelHashStorageMode.Database)
{
_dbContext.Database.ExecuteSqlRaw($"INSERT INTO {_options.MigrationHashTableName} (Hash) VALUES (@hash)", new SqlParameter("@hash", newHash));
}
else
{
File.WriteAllText(_options.MigrationFilePath, newHash);
}
}
private void CreateNewTables(string dbScript, MigrationModelHashStorageMode mode)
{
string executionScript;
if (mode == MigrationModelHashStorageMode.Database)
{
// Prepend create table script.
executionScript = string.Join(Environment.NewLine, new string[] { DbMetadataModel, dbScript });
}
else
{
executionScript = dbScript;
}
// Remove GO instructions since they are not compatible with ExecuteSqlCommand.
_dbContext.Database.ExecuteSqlRaw(executionScript.Replace("GO", string.Empty));
}
/// <summary>
/// Migrates your database schema to your database with the given settings.
/// </summary>
/// <param name="forceMigration">Forces the migration process even if there are no changes in the database schema.</param>
/// <param name="mode">Storage method of created schema hash.</param>
/// <param name="postMigration">Action reference for post migration process.</param>
public void Migrate(bool forceMigration, MigrationModelHashStorageMode mode, Action preMigration = null, Action postMigration = null)
{
// Get the existing model hash.
string currentHash = GetCurrentHash(mode);
// Create the database generation script.
string generatedScript = _dbContext.Database.GenerateCreateScript();
// Create a new hash from database generation script.
string newHash = Sha256(generatedScript);
// Check for a change
if (newHash != currentHash || forceMigration)
{
if (preMigration != null)
{
ExecuteBeforeMigration(preMigration);
}
// Woop-woop we have a change !
Console.WriteLine();
WriteMessage("DB model change detected. Executing migration..");
WriteMessage("Dropping all tables...");
// Drop all tables instead of dropping the database since some cloud providers are not compatible with that.
DatabaseUtils.DropTables(_dbContext);
WriteMessage("Creating new tables...");
// Create new tables from the generated script.
CreateNewTables(generatedScript, mode);
WriteMessage("Updating model hash...");
// Update the script hash.
UpdateScriptHash(newHash, mode);
WriteMessage("Database has been migrated successfully..");
// Check if we need to invoke a post process function.
if (postMigration != null)
{
ExecutePostMigration(postMigration);
}
}
}
private string GetCurrentHash(MigrationModelHashStorageMode mode)
{
if (mode == MigrationModelHashStorageMode.File)
{
if (File.Exists(_options.MigrationFilePath))
{
return(File.ReadAllText(_options.MigrationFilePath));
}
// No migration signature file. Just return empty.
return(string.Empty);
}
else
{
// Create a connection from the context
DbConnection conn = _dbContext.Database.GetDbConnection();
_dbContext.Database.CurrentTransaction?.Commit();
// Check for the connection state since it might be open already.
if (conn.State != ConnectionState.Open)
{
conn.Open();
}
// Execute a query to retrieve information about MIGRATION_SIGNATURE_DB_TABLE_NAME table.
DbDataReader reader = ExecuteReaderCommand(
"select * from sysobjects where name=@tableName and xtype=@xType",
new SqlParameter[] { new SqlParameter("@tableName", _options.MigrationHashTableName), new SqlParameter("@xType", "U") },
conn);
// Do we have the table ?
if (reader.HasRows)
{
// yep we do.
reader.Close();
// Read the hash from the table.
reader = ExecuteReaderCommand($"select TOP 1 [Hash] from {_options.MigrationHashTableName}", null, conn);
// Do we have a value in it ?
if (reader.HasRows)
{
reader.Read();
// Get the first column since we only read 1 column and we dont need to worry about null value here since the column is not nullable.
string retrievedHash = reader.GetString(0);
reader.Close();
return(retrievedHash);
}
else
{
// Nope just return empty.
reader.Close();
return(string.Empty);
}
}
else
{
// Nope just return empty.
reader.Close();
return(string.Empty);
}
}
}
