This isn't really Dapper-specific, actually, as it relates to any XML-serializeable object.. but it came up when I was storing an object using Dapper.

Anyways, say I have a user class. Normally, I'd do something like this:

class User
{
    public string SIN {get; private set;}
    public string DisplayName {get;set;}

    public User(string sin)
    {
        if (string.IsNullOrWhiteSpace(sin))
            throw new ArgumentException("SIN must be specified");
        this.SIN = sin;
    }
}

Since a SIN is required, I'd just create a constructor with a sin parameter, and make it read-only.

However, with a Dapper (and probably any other ORM), I need to provide a parameterless constructor, and make all properties writeable. So now I have this:

class User: IValidatableObject 
{
    public int Id { get; set; }
    public string SIN { get; set; }
    public string DisplayName { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    {
      // implementation
    }
}

This seems.. can't really pick the word, a bad smell?
A) I'm allowing to change properties that should not be changed ever after an object has been created (SIN, userid)

B) Now I have to implement IValidatableObject or something like that to test those properties before updating them to db.

So how do you go about it ?