Question

I have the following to classes(POCO’s?) where the second is supposed to extend the first.

I am guessing I need a property referencing the base instance, Business in this case, but do I also need a Constructor to “fill” that property since an Insurance Company can’t exist without a Business?

My reference for this is the underlying DB where tblInsuranceCompany has a FK constraint on column BusinessID back to tblBusiness.

Additionally, I am very new at OOP so please point out anything else you may see “wrong”. Thanks,

public class Business
{
    public int BusinessID { get; set; }

    public BusinessType BusinessType { get; set; }

    public string Name { get; set; }

    public string ContactName { get; set; }

    public string EmailAddress { get; set; }

    public DateTime? InactiveDate { get; set; }

    public IList<Address> Addresses { get; set; }

    public IList<Phone> Phones { get; set; }

    public string DisplayString { get { return this.ToString(); } }

    public override string ToString()
    {
        return String.Format("{0}: {1}", Name, BusinessType.TypeDescription);
    }
}

public class InsuranceCompany : Business
{
    public int InsuranceCompanyID { get; set; }

    public Business Business { get; set; }

    public InsuranceCompanyType InsuranceCompanyType { get; set; }

    public string DRIInsuranceCompanyNumber { get; set; }

    public string DisplayString { get { return this.ToString(); } }

    public override string ToString()
    {
        return String.Format("{0}: {1}", Business.Name, InsuranceCompanyType.TypeDescription);
    }
}

Answer 1

I am guessing I need a property referencing the base instance, Business in this case,

No, you don’t need this. The InsuranceCompany is the business. It will also have all of the properties of Business since it inherits from Business. You don’t need a property to reference this, as the reference to the InsuranceCompany object will be the same reference as the reference to the “business” portion (they’re the same object).

but do I also need a Constructor to “fill” that property since an Insurance Company can’t exist without a Business?

All classes get a constructor – When you construct an InsuranceCompany, it will effectively construct the “business” as well.

That being said, you may want a constructor that passes the relevant information to the base class constructor – but if you don’t provide one, the compiler will create a default constructor for you.