C# 当一个类位于另一个类中时，如何从datareader中获取数据？

我正在做一个项目，它需要从数据库中获取数据，我在编写从datareader加载数据并使其工作的方法时遇到了一些问题

在这个特定的模型中，除其他外，我有以下两个类，定义如下：

AUTHOR
private string authFirstName;
private string authLastName;
private Country country;

COUNTRY
private int countryId;
private string countryName;

public class Author
{
    public string AuthFirstName {get; set;}
    public string AuthLastName {get; set;}
    public Country Country {get; set;}
}

public class Country
{
    public int CountryId {get; set;}
    public int CountryName {get; set;}
}

这是我编写的代码示例，它不起作用，这意味着VisualStudio将其标记为错误。我不知道有谁能在这件事上帮我一点忙

protected static Author LoadFromReader(IDataRecord row)
{
    Author a = null;
    if (row != null)
    {
        a = new Author
        {
            AuthFirstName = row.GetString(row.GetOrdinal("authName")),
            AuthLastName = row.GetString(row.GetOrdinal("authLName")),
            country.CountryId = row.GetInt32(row.GetOrdinal("countryID")),

        };
    }
    return a;
}

---

假设您有这两个类，定义如下：

AUTHOR
private string authFirstName;
private string authLastName;
private Country country;

COUNTRY
private int countryId;
private string countryName;

public class Author
{
    public string AuthFirstName {get; set;}
    public string AuthLastName {get; set;}
    public Country Country {get; set;}
}

public class Country
{
    public int CountryId {get; set;}
    public int CountryName {get; set;}
}

方法如下所示

protected static Author LoadFromReader(IDataRecord row)
{
    Author a = null;
    if (row != null)
    {
        a = new Author
        {
            AuthFirstName = row.GetString(row.GetOrdinal("authName")),
            AuthLastName = row.GetString(row.GetOrdinal("authLName")),
            Country = new Country
            {
               CountryId = row.GetInt32(row.GetOrdinal("countryID"))
            },
        };
    }
    return a;
}

---

在分配属性之前，您需要在上创建Country类的实例

visual studio给您的错误是什么？如果您可以包含有关您要求我们修复的错误的信息，将对我们有很大帮助。什么是Country？我在代码中没有看到任何东西显示最初声明的位置。