Question

Can anyone provide me with a web-link which describes attribute-based simple one-to-many mapping very clearly?

For example (A company can have only one country of origin. But there are many Companies in a Country):

class Company
{
}

class Country
{
    IList<Company> Items;
}

Answer 1

For your example class, and using a bag for an unordered collection:

using Map = NHibernate.Mapping.Attributes;

[Map.Class( 0, Table = "country", NameType=typeof(Country) )]
public class Country
{
    [Map.Id( 1, Name = "Id" )]
    [Map.Generator( 2, Class = "identity" )]
    public virtual int Id { get; set; }
    [Map.Property]
    public virtual string Name { get; set; }
    [Map.Bag( 0, Table = "country_company" )]
    [Map.Key( 1, Column = "countryid" )]
    [Map.OneToMany( 2, ClassType = typeof( Company ) )]
    public virtual IList<Company> Items { get; set; } 
}

[Map.Class( 0, Table = "country_company", NameType = typeof( Company ) )]
public class Company
{
    [Map.Id( 1, Name = "Id" )]
    [Map.Generator( 2, Class = "identity" )]
    public virtual Guid Id { get; set; }
    [Map.Property]
    public virtual string Name { get; set; }
}

produces the following hbm.xml:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
    <class name="nh.Country, nh" table="country">
        <id name="Id">
            <generator class="identity" />
        </id>
        <property name="Name" />
        <bag name="Items" table="country_company">
            <key column="countryid" />
            <one-to-many class="nh.Company, nh" />
        </bag>
    </class>
    <class name="nh.Company, nh" table="country_company">
        <id name="Id">
            <generator class="identity" />
        </id>
        <property name="Name" />
    </class>
</hibernate-mapping>