许多一对多的关系对象FluentNHibernate查询 [英] FluentNHibernate query on many-to-many relationship objects
问题描述
出于某种原因,我不能让这个查询的权利,我不明白为什么...
For some reason i can't get this query right, and i can't understand why...
我有一个名为'博客',有一个对象一个标识,以及标签的。
每个'标签列表'有一个ID和一个名称属性。
I have an object called 'Blog' that has an Id, and a list of 'Tag's.
Each 'Tag' has an id and a 'Name' property.
由于这是。一个多对多的关系,我已要求另一个表blog_tags将它们连接
Since this is a many to many relationship, I have another table called 'blog_tags' connecting them.
的映射是这样的:
public class BlogsMapping : ClassMap<Blog>
{
Table("blogs");
Id(x => x.Id).GeneratedBy.Identity();
Map(x => x.Content);
HasManyToMany(x => x.Tags)
.Table("Blog_Tags")
.ParentKeyColumn("BlogId")
.ChildKeyColumn("TagId")
.Not.LazyLoad()
.Cascade.All();
}
public class TagsMapping : ClassMap<Tag>
{
Table("tags");
Id(x => x.Id).GeneratedBy.Identity();
Map(x => x.Name);
}
我想检索具有以下所有的博客列表( 。标签部分名单)
I would like to retrieve a list of blogs that have all of the following (some list) of tags.
我愿做这样的事情:
public IList<Blog> Filter(string[] tags)
{
var blogs = _session.QueryOver<Blog>()
.Where(x => x.Tags.ContainsAll(tags));
return blogs.ToList();
}
我尝试了几种不同的方法,但总是碰上不同的,奇怪的错误,所以我希望有人可以只点我在正确的方向...
I tried a couple of different ways, but always run into different and weird errors, so i was hoping that someone could just point me in the right direction...
推荐答案
您应该能够做到这一点像这样的东西:
You should be able to do it with something like this:
string[] tagNames = new string[2]{ "Admins", "Users" };
using (NHibernate.ISession session = SessionFactory.GetCurrentSession())
{
IList<Blog> blogsFound = session.QueryOver<Blog>()
.Right.JoinQueryOver<Tags>(x => x.Tags)
.WhereRestrictionOn(x => x.Name).IsIn(tagNames)
.List<Blog>();
}
修改
以下是我在谈论的子查询。它不是一个真正的子查询,但你必须第一个获得您不希望在搜索结果中包含的值(标签名)的列表。
Edit
The below is what I was talking about with the subquery. It's not really a subquery but you have to 1st get a list of values (tag names) that you don't want to include in your results.
string[] tagNames = new string[2]{ "Admins", "Users" };
IList<string> otherTags =
session.QueryOver<Tag>()
.WhereRestrictionOn(x => x.Name).Not.IsIn(tagNames)
.Select(x => x.Name)
.List<string>();
string[] otherTagNames = new string[otherTags.Count];
otherGroups.CopyTo(otherTagNames, 0);
IList<Blog> blogsFound =
session.QueryOver<Blog>()
.Right.JoinQueryOver<Tag>(x => x.Tags)
.WhereRestrictionOn(x => x.Name).IsIn(tagNames)
.WhereRestrictionOn(x => x.Name).Not.IsIn(otherTagNames)
.List<Blog>();
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