public class UserRepository 

{

    private readonly string connectionString;

​

    public UserRepository(IConfiguration configuration) 

    {

        connectionString = configuration.GetConnectionString("DefaultConnection");

    }

​

    public string GetUserByEmail(string email)

    {

        var connection = GetOpenConnectionAsync(connectionString).Result;

        var sql = "SELECT FROM users WHERE user_email = '" + email + "'";

​

        return connection.QueryFirstOrDefault(sql);

    }

​

    private async Task<NpgsqlConnection> GetOpenConnectionAsync(string connectionString) 

    {

        var connStr = connectionString;

​

        using var connection = new NpgsqlConnection(connStr);

        await connection.OpenAsync();

​

        return connection;

    }

}