Impement IEquatable on EmailAddress to Filter Duplicates

[NuNn-DaDdY]

Issue Summary

By implementing IEquatable on EmailAddress you'd be able to filter out duplicate emails when calling methods such as AddTo(s), AddCC(s), and AddBCC(s).

IEquatable Implementation

public class EmailAddress : IEquatable<EmailAddress>
{
	public EmailAddress()
	{
	}

	public EmailAddress(string email, string name = null)
	{
		this.Email = email;
		this.Name = name;
	}

	[JsonProperty(PropertyName = "name")]
	public string Name { get; set; }

	[JsonProperty(PropertyName = "email")]
	public string Email { get; set; }

	public bool Equals(EmailAddress other)
	{
		if (other == null) 
		{
			return false;
		}			
		return (this.Email == other.Email);
	}
	
	public override bool Equals(Object obj)
	{
		if (obj == null)
		{
			return false;
		}
		var email = obj as EmailAddress;
		return Equals(email);
	}
	
	public override int GetHashCode()
	{
		return this.Email.GetHashCode();
	}
	
	public static bool operator == (Email emailOne, Email emailTwo)
	{
		if (((object)emailOne) == null || ((object)emailTwo) == null)
		{
			return Object.Equals(emailOne, emailTwo);
		}
		return emailOne.Equals(emailTwo);
	}
	
	public static bool operator != (Email emailOne, Email emailTwo)
	{
		if (((object)emailOne) == null || ((object)emailTwo) == null)
		{
			return !Object.Equals(emailOne, emailTwo);
		}
		return !emailOne.Equals(emailTwo);
	}
}

Sample: SendGridMessage.AddTo() Taking Advantage of the IEquatable

public void AddTos(List<EmailAddress> emails, int personalizationIndex = 0, Personalization personalization = null)
{
	if (personalization != null)
	{
                // Using Union in place of AddRange
		personalization.Tos.Union(emails);
		if (this.Personalizations == null)
		{
			this.Personalizations = new List<Personalization>();
			this.Personalizations.Add(personalization);
		}
		else
		{
			this.Personalizations.Add(personalization);
		}

		return;
	}

	if (this.Personalizations != null)
	{
		if ((personalizationIndex != 0) && (this.Personalizations.Count() <= personalizationIndex))
		{
			var p = new Personalization();
			this.Personalizations.Insert(personalizationIndex, p);
		}

		if (this.Personalizations[personalizationIndex].Tos == null)
		{
			this.Personalizations[personalizationIndex].Tos = new List<EmailAddress>();
		}

                // Using Union in place of AddRange
		this.Personalizations[personalizationIndex].Tos.Union(emails));
		return;
	}

	this.Personalizations = new List<Personalization>()
	{
		new Personalization()
		{
                        // Get rid of any duplicates with Distinct
			Tos = emails.Distinct()
		}
	};
	return;
}

Technical details:

• sendgrid-csharp Version: master (latest commit: [commit number])
• .NET Version: 4.6.1

[ottomatic]

Good suggestion.

But then the comparisons should really be case insensitive. So instead of

return (this.Email == other.Email);

It should be:

return (this.Email.ToLower() == other.Email.ToLower());

And instead of:
return this.Email.GetHashCode();

It should be:
return this.Email.ToLower().GetHashCode();

The code assume that the Email property is always non-null. Perhaps that is not always the case, so null checks will need to be inserted in a few places?

[NuNn-DaDdY]

I agree with the case insensitive comparisons and with the non-null check(s). I overlooked the Email property having a public setter so the Equals(EmailAddress other) and GetHashCode would want to check for null. A null/empty check could also be added to the constructor when the email and name are passed in:

public EmailAddress(string email, string name = null)
{
	if (string.IsNullOrWhiteSpace(email))
	{
		throw new ArgumentException(nameof(email));
	}
	this.Email = email.Trim();	
	this.Name = (string.IsNullOrWhiteSpace(name)) ? null : name.Trim();
}