NHibernate Many to Many delete all my data in the table

Posted by Daoming Yang on Stack Overflow See other posts from Stack Overflow or by Daoming Yang
Published on 2010-01-04T23:37:29Z Indexed on 2010/04/02 18:03 UTC
Read the original article Hit count: 282

Filed under:

nhibernate

I would love to thank @Stefan Steinegger and @David helped me out yesterday with many-to-many mapping.

I have 3 tables which are "News", "Tags" and "News_Tags" with Many-To-Many relationship and the "News_Tags" is the link table.

If I delete one of the news records, the following mappings will delete all my news records which have the same tags. One thing I need to notice, I only allowed unique tag stored in the "Tag" table.

This mapping make sense for me, it will delete the tag and related News records, but how can I implement a tagging system with NHibernate?

Can anyone give me some suggestion? Many thanks.

Daoming.

News Mapping:

<class name="New" table="News" lazy="false">
    <id name="NewID">
      <generator class="identity" />
    </id>
    <property name="Title" type="String"></property>
    <property name="Description" type="String"></property>

<set name="TagsList" table="New_Tags" lazy="false" inverse="true" cascade="all">
      <key column="NewID" />
      <many-to-many class="Tag" column="TagID" />
    </set>
</class>

Tag Mapping:

<class name="Tag" table="Tags" lazy="false">
    <id name="TagID">
    <generator class="identity" />
    </id>
    <property name="TagName" type="String"></property>
    <property name="DateCreated" type="DateTime"></property>

    <!--inverse="true" has been defined in the "News mapping"-->
    <set name="NewsList" table="New_Tags" lazy="false" cascade="all">
      <key column="TagID" />
      <many-to-many class="New" column="NewID" />
    </set>
</class>

Related posts about nhibernate

How can I eager-load a child collection mapped to a non-primary key in NHibernate 2.1.2?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have two objects with a many-to-many relationship between them, as follows: public class LeftHandSide { public LeftHandSide() { Name = String.Empty; Rights = new HashSet<RightHandSide>(); } public int Id { get; set; } public string Name { get; set;… >>> More
Nhibernate 2.1 and mysql 5 - InvalidCastException on Setup

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello there, I am trying to use NHibernate with Spring.Net und mySQL 5. However, when setting up the connection and creating the SessionFactoryObject, I get this InvalidCastException: NHibernate seems to cast MySql.Data.MySqlClient.MySqlConnection to System.Data.Common.DbConnection which causes… >>> More
Nhibernate transactions:Avoiding Nhibernate dependency in the service layer

as seen on Stack Overflow - Search for 'Stack Overflow'
One of practices advocated by Nhibernate experts is to do all actions in inside a transaction. In a typical 3 tier web architecture, Nhibernate depedency is limited the data layer. In such a case is it fine to use using (var tr = NHibernateSession.Current.BeginTransaction()) { at the controller… >>> More
Series of abstract classes and NHibernate

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, and first off thanks for your time to look at this. For a research project I'm working on, I have a somewhat complex design (which I've been given) to persist to a database via NHibernate. Here's an example of the class hierarchy: TransitStrategy, TransportationCompany and TransportationLocation… >>> More
Using Time columns with NHibernate, Fluent NHibernate and SQL Server 2008

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I have a table with a time column in my SQL Server 2008 database. The property of the object I'm trying to map to is a TimeSpan. How can i tell FluentNHibernate to use the TimeAsTimeSpan NHibernate type, so that I don't have cast problems? >>> More

Developer IT