#First one: Single Responsibility Principle (SRP)
Basics Of SOLID Design Principles Using C# and .NET S: Single Responsibility Principle (SRP) O: Open closed Principle (OCP) L: Liskov substitution Principle (LSP) I: Interface Segregation Principle (ISP) D: Dependency Inversion Principle (DIP)
S: Single Responsibility Principle (SRP)
Example:
public class UserService
{
public void Register(string email, string password)
{
if (!ValidateEmail(email))
throw new ValidationException("Email is not an email");
var user = new User(email, password);
SendEmail(new MailMessage("mysite@nowhere.com", email) { Subject="HEllo foo" });
}
public virtual bool ValidateEmail(string email)
{
return email.Contains("@");
}
public bool SendEmail(MailMessage message)
{
_smtpClient.Send(message);
}
}
The SendEmail and ValidateEmail methods have nothing to do within the UserService class. Let's refract it.
public class UserService
{
EmailService _emailService;
DbContext _dbContext;
public UserService(EmailService aEmailService, DbContext aDbContext)
{
_emailService = aEmailService;
_dbContext = aDbContext;
}
public void Register(string email, string password)
{
if (!_emailService.ValidateEmail(email))
throw new ValidationException("Email is not an email");
var user = new User(email, password);
_dbContext.Save(user);
emailService.SendEmail(new MailMessage("myname@mydomain.com", email) {Subject="Hi. How are you!"});
}
}
public class EmailService
{
SmtpClient _smtpClient;
public EmailService(SmtpClient aSmtpClient)
{
_smtpClient = aSmtpClient;
}
public bool virtual ValidateEmail(string email)
{
return email.Contains("@");
}
public bool SendEmail(MailMessage message)
{
_smtpClient.Send(message);
}
}