Object cannot be cast from DBNull to other types in constructor

Question

I need to add into the list one object CompanyDetails, so I get data from my database, and load it into constructor.

result.Add(new CompanyDetails() { 
    Name = dr["name"].ToString(), 
    City = dr["city"].ToString(), 
    StreetName = dr["streetName"].ToString(), 
    StreetNr = Convert.ToInt32(dr["apartmentNr"]), 
    Tax = int.Parse(dr["TAX"].ToString() )});

StreetNr and Tax can have null value. And when I'm trying to run it i get the error:

Object cannot be cast from DBNull to other types

How can I fix it? I know that normally I should check if tax or streetNr equals DBNull or not, but I don't know how I can do it in this case.

this is class CompanyDetails:

public class CompanyDetails
{
    public string Name { get; set; }
    public string City { get; set; }
    public string StreetName { get; set; }
    public int? StreetNr { get; set; }
    public int? Tax { get; set; }

}

Answer 1

Tax = dr["TAX"] == DBNull.Value ? 0 : (int)dr["TAX"]

That will check if it's null, if it is, it sets the int value to 0, otherwise it assigns the integer value.

Applying that to your code:

result.Add(new CompanyDetails() { 
    Name = dr["name"].ToString(), 
    City = dr["city"].ToString(), 
    StreetName = dr["streetName"].ToString(), 
    StreetNr = dr["apartmentNr"] == DBNull.Value ? 0 : (int)dr["apartmentNr"]
    Tax = dr["TAX"] == DBNull.Value ? 0 : (int)dr["TAX"]
    )});

EDIT:
In case StreetNr and Tax are already of type int?, then just assign null instead of 0.

result.Add(new CompanyDetails() { 
    Name = dr["name"].ToString(), 
    City = dr["city"].ToString(), 
    StreetName = dr["streetName"].ToString(), 
    StreetNr = dr["apartmentNr"] == DBNull.Value ? (int?)null : (int)dr["apartmentNr"]
    Tax = dr["TAX"] == DBNull.Value ? (int?)null : (int)dr["TAX"]
    )});