建模NHibernate的查询 [英] Modeling NHibernate queries

问题描述

通常我会把我的规定 - / HQL查询，在库/ DAL类相关的实体，但最近I'be一直在想补充说，重新presents查询是另一种抽象的，这会给我加入共同的行为在一个基类，等所有的查询（如分页）的可能性。

Usually I'd put my criterias/hql queries in a repository/dal class related to the entity, but lately I'be been thinking of adding another abstraction that represents what a query is, this would give me the possibility of adding common behavior to all queries (e.g. pagination) in a base class, etc.

所以这些都是我的组件现在;

so these are my components now;

不相关的NHibernate的通用接口：

generic interface not related to nhibernate:

public interface IQuery<T>
{
    IList<T> List();
    T Single();
}

例实施基于标准的查询，类似的事情可能与HQL语句来完成，或NHibernate的，LINQ查询

Example implementation of a Criteria based query, something similar could be done with an Hql query, or a nhibernate-linq query

public abstract class CriteriaQuery<T>: IQuery<T>
{
    [Inject]
    public ISessionFactory SessionFactory { protected get; set; }

    protected ISession Session
    {
        get { return SessionFactory.GetCurrentSession(); }
    }

    protected abstract ICriteria Configure(ICriteria criteria);

    [Transaction]
    public virtual IList<T> List()
    {
        var criteria = Session.CreateCriteria(typeof (T));

        return Configure(criteria)
                 .List<T>();
    }

    [Transaction]
    public virtual T Single()
    {
        return Configure(Session.CreateCriteria(typeof(T)))
                .UniqueResult<T>();
    }
}

和这里的域特定的查询将如下所示：

and here a domain specific query would look like:

public interface IGetVideosQuery: IQuery<Video>
{
    IGetVideosQuery Page(int index);
    IGetVideosQuery PageSize(int pageSize);

    IGetVideosQuery AllTime { get; }
    IGetVideosQuery Today { get; }
    IGetVideosQuery LastWeek { get; }
}

对此有何想法？你看到的可能出现的问题我可能会遇到？ 谢谢！

any thoughts on this? possible problems you see I might come across? Thanks!

推荐答案

我选择了另一条路，那的 CQS 。这里做的事情是，它从我的查询逻辑分开我的不同诱变逻辑。

I took a different path, that of CQS. What this does is that it separates my mutating logic from my query logic.

现在，对于如何实现这个不同的想法，而我选择这一个：

Now, there are different ideas on how to implement this, and I choose this one:

• 我所有的变异逻辑是使用命令如 DeactivateUser 并启动 ChangeRelationAddress 。对于这个业务逻辑，我有正常的存储库像你描述;

• All my mutation logic is activated using command like DeactivateUser and ChangeRelationAddress. For this business logic, I have normal repositories like you describe;

有关数据显示，我用一个完全管理的系统。有了这个系统，我形容像规范模式查询。我介绍了基表和字段。该查询系统会自动创建联接为我和我提供的过滤器过滤器的定义。

For displaying data, I use a completely managed system. With this system, I describe queries like the Specification Pattern. I describes the base table and the fields. The query system automatically creates the joins for me and with filter definitions I provide filters.

这个系统可以让我保持我的仓库复杂了，因为我没有去想过滤器，用户可设置或 ORDER BY 的。使用标准，这个数据会自动显示系统创建过滤器和处理分页我。

This system allows me to keep the complexity of my repositories down because I do not have to think about filters a user may set or ORDER BY's. The system that displays this data automatically creates the filters using Criteria and handles paging for me.

也许这样的系统可以为你工作。

Maybe such a system can work for you.

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