How do I assign an instance of a struct to a class that contains that struct?

Question

I've never used structs before. I've created a simple example of what I'm trying to do below. The reason I've chosen struts is because the object will never need to exist outside the context of the class. Thanks.

Classes

public class EmailAddress
{
    public string Email { get; set; }

    public string Name { get; set; }
}


public class EmailMessage
{
    public EmailAddress To { get; set; }

    public EmailAddress From { get; set; }

    public string Subject { get; set; }

    public string Body { get; set; }

    public struct Attachment
    {
        public string Name { get; set; }

        public string Bas64 { get; set; }
    }

Attempted Method

protected void MyMethod()
{
    var myEmailMessage = new EmailMessage
    {
        To = { Email = "ToEmailAddress" }, 
        From = { Email = "FromEmailAddress" }
    };

    var myAttachment = new EmailMessage.Attachment
    {
        Name = "AttachmentName", 
        Bas64 = "Base64String"
    };

    myEmailMessage.Attachment = myAttachment;
}

Answer 1

You can't use a struct declaration as property of your class. You should split the property and the actual struct definition.

Try this:

public _Attachment Attachment {get;set;} /* Attachment as property */

public struct _Attachment /* The definition of the struct */
{
    public string Name { get; set; }

    public string Bas64 { get; set; }
}

And use it like this:

var myAttachment = new EmailMessage._Attachment
{
    ...
}

By the way: there is no real need for a struct. Using a class would be fine too.

Answer 2

Your problem is that myEmailMessage.Attachment = my Attachment; is attempting to assign something to a member called Attachment. The problem is that you don't have a property called Attachment on your class. You have declared a struct called that but that is just a declaration and doesn't create a property or anything else like that.

What you'd need is to have an actual property on your class that you could then assign an instance of Attachment to.

Answer 3

Your EmailMessage class doesn't have an Attachment property, only an Attachment nested type.

You should rename the Attachment struct to EmailAttachment to avoid name conflicts, and create an Attachment property:

public class EmailMessage
{
    public EmailAddress To { get; set; }

    public EmailAddress From { get; set; }

    public string Subject { get; set; }

    public string Body { get; set; }

    public EmailAttachment Attachment { get; set; }

    public struct EmailAttachment
    {
        public string Name { get; set; }

        public string Bas64 { get; set; }
    }
}