Question

我是Fluent NHibernate的完整菜鸟，我正在使用基于推荐的查询对象模式。我也是新手。我会尽量保持代码示例的简洁和有用。

用户类：

public class User {
    public Guid ID { get; set; }
    public string Name { get; set; }
}

可见性：

public enum VisibilityType {
    Anybody,
    OwnersOnly,
    Nobody
}

汽车类：

public class Car {
    public Guid ID { get; set; }
    public VisibilityType Visibility { get; set; }
    public ICollection<User> Owners { get; set; }
}

所以我需要为查询对象编写一个条件限制方法。返回所有VisibilityType.Public的汽车，但如果汽车的Visibility属性值为VisibilityType.OwnersOnly，则限制返回属于该组的用户。

这是我目前使用的限制方法，但没有条件：

public class CarQueryObject
{

    private User user { get; set; }
    private const string OwnersProperty = "Owners";
    private const string OwnersIDProperty = "Owners.ID";

    public CarQueryObject RestrictToOwners()
    {
        // How do I add a conditional criteria here?  Only restrict by owner
        // if the QueryObject has VisibilityType.OwnersOnly?  Note that it should
        // *NOT* restrict VisibilityType.Anybody
        CreateOwnersAlias();
        Criteria.Add(Restrictions.Eq(OwnersIDProperty, user.Id));
        return this;
    }

    public CarQueryObject JoinFetchOwned()
    {
        Criteria.SetFetchMode(OwnersProperty, FetchMode.Join);
        return this;
    }

    public void CreateOwnersAlias()
    {
        Criteria.CreateAlias(OwnersProperty, OwnersProperty, JoinType.LeftOuterJoin);
        JoinFetchOwned();
    }
}

？_？

Answer 1

获得展示汽车的想法

var carsShown = session.CreateCriteria<Car>()
    .JoinAlias("Owner", "owner")
    .Add(Expressions.Or(
        Expression.Eq("Visibility", Visibility.Anybody),
        Expression.Eq("Visibility", Visibility.OwnersOnly) && Expression.Eq("owner.Id", currentUser.Id)
    ))
    .List<Car>();

使用查询对象模式的流畅NHibernate中的条件限制

1 个答案: