如何使用Castle ActiveRecord预加载包含父子自引用的记录？

My SQL table looks like this:

我的SQL表看起来像这样:

CREATE TABLE Page (
    Id int primary key,
    ParentId int, -- refers to Page.Id
    Title varchar(255),
    Content ntext
)

and maps to the following class in my ActiveRecord model:

并映射到ActiveRecord模型中的以下类:

[ActiveRecord]
public class Page {

    [PrimaryKey]
    public int Id { get; set; }

    [BelongsTo("Parent")]
    public virtual Page Parent { get; set; }

    [Property]
    public string Title { get; set; }

    [Property]
    public string Content { get; set; }

    [HasMany(typeof(Page), "Parent", "Page")]
    public IList<Page> Children { get; set; }
}

I'm using ActiveRecord to retrieve the tree roots using the following code:

我正在使用ActiveRecord使用以下代码检索树根:

var rootPages = new SimpleQuery<Page>(@"from Page p where p.Parent is null");
return(rootPages.Execute());

This gives me the correct object graph, but a SQL Profiler trace shows that child pages are being loaded by a separate query for every non-leaf node in the tree.

这为我提供了正确的对象图,但SQL事件探查器跟踪显示,对于树中的每个非叶节点,子页都由单独的查询加载。

How can I get ActiveRecord to load the whole lot up front ("SELECT * FROM Page") and then sort the in-memory objects to give me the required parent-child relationships?

如何让ActiveRecord预先加载整个批次(“SELECT * FROM Page”)然后对内存中的对象进行排序以获得所需的父子关系?

2 个解决方案

#1

The easiest way to do this is to fetch the entire table, then filter the result. This is pretty easy, if you are using linq.

最简单的方法是获取整个表,然后过滤结果。如果您使用linq,这非常简单。

var AllPages = ActiveRecordMediator<Page>.FindAll();
var rootPages = AllPages.Where(p => p.Parent == null);

#2

-1

Try this:

var rootPages = new SimpleQuery<Page>(@"from Page p left join fetch p.Children where p.Parent is null");
return(rootPages.Execute());

This will cause the Children collection of each Page in the result set to be populated out during the initial query, which should reduce your overall query load to a single query.

这将导致在初始查询期间填充结果集中每个页面的Children集合,这会将您的整体查询负载减少到单个查询。

#1