Question

我正在处理一个项目，该项目需要从数据库中提取数据，而且我在编写方法时会遇到一些麻烦，无法从数据加载器加载数据并使其正常工作。

在这个特定的模型中，我有这两个类，定义如下：

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

COUNTRY
private int countryId;
private string countryName;

这是我编写的代码示例，但它不起作用（意味着visual studio将其标记为错误）。我想知道是否有人能帮助我解决这个问题。

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;
}

Answer 1

假设你有这两个类，定义如下：

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;}
}

该方法看起来像这样

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;
}

您需要在分配属性之前创建Country类的实例

如果在另一个类中有一个类，如何从datareader获取数据？

1 个答案: