C# class constructor assigning to 'this'

Question

I have a \'naïve\' question.

With the following sample code:

public class ThisClass
{
    public int ThisClassID { get; set; }
    public string ThisValu         


        

Answer 1

You should take a look at AutoMapper, and your code could look as follows:

// Somewhere in your application/service initialization class and in some method...
Mapper.CreateMap<ThisClass, ThisClass>();

public class ThisClass
{
    public int ThisClassID { get; set; }
    public string ThisValue { get; set;}

    public ThisClass()
    {
    }

    public ThisClass(int thisClassID)
    {
        using (MyContext dbContext = new MyContext())
        {
            Mapper.Map(dbContext.CaseNotes.Find(thisClassID), this);
        }
    }
}

BTW it sounds like a bad idea. I wouldn't populate a domain object inside its own constructor.

This is a good responsibility for the repository.

Answer 2

Is there any way of creating a simple constructor that returns database entities into this?

In practice no. In theory you can make the type a struct. Then, the code should compile. You can assign to this in a struct.

Probably, you should not use a constructor at all. Create a factory method that simply returns the result from Find.

One unchangeable fact about constructors is that they create a fresh object every time. I don't think you want that here. You probably want to preserve the existing object instance and its identity.