Dapper Transaction Dynamic Parameters


The dynamic parameters allow you to specify parameters when you need to send parameters into a stored procedure or an SQL Statment. You can also use the anonymous type method that we have used in the previous articles.

Let's consider the following simple example, which retrieves the author data, including books using the anonymous type method.

private static Author GetAuthorAndTheirBooksSP(int id)
{
    string sql = "GetAuthor";

    using (IDbConnection connection = new SqlConnection(ConnectionString))
    {
        connection.Open();

        using (var transaction = connection.BeginTransaction())
        {
            using (var results = transaction.QueryMultiple(sql, new { Id = id }, commandType: CommandType.StoredProcedure))
            {
                var author = results.Read<Author>().SingleOrDefault();
                var books = results.Read<Book>().ToList();

                if (author != null && books != null)
                {
                    author.Books = books;
                }

                return author;
            }
        }
    }
}

The DynamicParameters class allows you to specify very explicit parameters.

private static Author GetAuthorAndTheirBooksSPUsingDynamicParameters(int id)
{
    string sql = "GetAuthor";

    DynamicParameters parameter = new DynamicParameters();
    parameter.Add("@Id", id);

    using (IDbConnection connection = new SqlConnection(ConnectionString))
    {
        connection.Open();

        using (var transaction = connection.BeginTransaction())
        {
            using (var results = transaction.QueryMultiple(sql, parameter, commandType: CommandType.StoredProcedure))
            {
                var author = results.Read<Author>().SingleOrDefault();
                var books = results.Read<Book>().ToList();

                if (author != null && books != null)
                {
                    author.Books = books;                            
                }

                return author;
            }
        }
    }
}

It is almost like a generic list you can call. Let's have a look into another example that inserts an author into the database using dynamic parameters.

private static void InsertSingleAuthorUsingDynamicParameters()
{
    using (IDbConnection connection = new SqlConnection(ConnectionString))
    {
        connection.Open();

        using (var transaction = connection.BeginTransaction())
        {
            DynamicParameters parameter = new DynamicParameters();

            parameter.Add("@FirstName", "William");
            parameter.Add("@LastName", "Shakespeare");

            string sqlQuery = "INSERT INTO Authors (FirstName, LastName) VALUES(@FirstName, @LastName)";

            int rowsAffected = transaction.Execute(sqlQuery, parameter);
        }
    }
}