I have a qouestion regarding the AutoMap xml generation.
I have two classes:
public class User
{
virtual public Guid Id { get; private set; }
virtual public String Name { get; set; }
virtual public String Email { get; set; }
virtual public String Password { get; set; }
virtual public IList<OpenID> OpenIDs { get; set; }
}
public class OpenID
{
virtual public Guid Id { get; private set; }
virtual public String Provider { get; set; }
virtual public String Ticket { get; set; }
virtual public User User { get; set; }
}
The generated sequences of xml files are:
For User class:
<bag name="OpenIDs">
<key>
<column name="User_Id" />
</key>
<one-to-many class="BL_DAL.Entities.OpenID, BL_DAL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</bag>
For OpenID class:
<many-to-one class="BL_DAL.Entities.User, BL_DAL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" name="User">
<column name="User_id" />
</many-to-one>
I don't see the inverse=true attribute for the User mapping. Is it a normal behavior, or I made a mistake somewhere?
The default convention is not to add the inverse attribute. You will have to overwrite the convention to change that.
Related
A Teacher has a one-to-one with a Student.
A SpecialTeacher extends Teacher but deals specifically with SpecialStudents.
Using table per class in the hierarchies.
public class Teacher
{
public virtual int Id { get; set; }
public virtual int DepartmentId { get; set; }
public virtual String Name { get; set; }
public virtual Student Student { get; set; }
}
public class SpecialTeacher : Teacher
{
public virtual string TelephoneNumber { get; set; } //SpecialTeachers get to have a phone
public virtual SpecialStudent SpecialStudent { get { return (SpecialStudent)base.Student; } set { Student = value; } }
}
public class Student
{
public virtual int Id { get; set; }
public String Name { get; set; }
}
public class SpecialStudent : Student
{
public int SpecialMark { get; set; }
}
and the associated mappings:
<class name="Student">
<id name="Id" />
<property name="Name" />
</class>
<joined-subclass name="SpecialStudent" extends="Student">
<key column="Id" />
<property name="SpecialMark" />
</joined-subclass>
<class name="Teacher">
<id name="Id" />
<property name="DepartmentId" />
<property name="Name" />
<many-to-one name="Student" column="StudentId" />
</class>
<joined-subclass name="SpecialTeacher" extends="Teacher">
<key column="Id" />
<property name="TelephoneNumber" />
</joined-subclass>
So, let's say that we want to get the average mark for SpecialStudents for a given department:
public double GetAverageScoreForSpecialStudentsByDepartment(int departmentId)
{
return CurrentSession.Query<SpecialTeacher>()
.Where(st => st.DepartmentId == departmentId)
.Average(ss => ss.SpecialStudent.SpecialMark);
}
The test will fail because it will complain that SpecialStudent is not a mapped property of SpecialTeacher.
The only way that I can think of avoiding this issue is to map the property, but this is duplication since the base Teacher is already mapped to the Student hierarchy.
Update
I meant to also mention that previously we had the SpecialTeacher set up like:
public class SpecialTeacher : Teacher
{
public virtual string TelephoneNumber { get; set; } //SpecialTeachers get to have a phone
public virtual new SpecialStudent Student { get { return (SpecialStudent)base.Student; } set { Student = value; } }
}
which did appear to work ok, but Envers did not work with it when retrieving audited data.
The only way that I can think of avoiding this issue is to map the property, but this is duplication since the base Teacher is already mapped to the Student hierarchy.
This is not duplication as you never mapped the SpecialStudent property in the SpecialTeacher mapping file. Although you correctly defined the relationship in code, NHibernate has no way of knowing a SpecialTeacher is suppose to have a SpecialStudent. The code is use by NHibernate to recreate the object from the tables, but only if you define the correct relationships in your mapping.
Remeber that BaseTeacher to BaseStudent does not imply SpecialTeacher to SpecialStudent relationship.
I have two entities like
public class Person
{
public int PersonId { get; set; }
public string Name { get; set; }
public int DataId { get; set; }
}
public class Data
{
public int DataId { get; set; }
public string details { get; set; }
public int PersnId{ get; set; }
}
as you see both table are relate to each other. I want a solution to insert data in both table at once. I 1-insert person, 2-insert data and then update person and it works but I'm looking for way to eliminate Update.
My mapping for person table:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="TestNhibrinate" assembly="TestNhibrinate">
<class name="TestNhibrinate.Entites.Person" table="Person" lazy="false">
<id name="PersonId" column="PersonId" type="int" >
<generator class="identity" />
</id>
<property name="Name" column="Name" type="String" length="50" />
<many-to-one name="Adress" class="TestNhibrinate.Entites.Adress" column="AdressId"/>
</class>
</hibernate-mapping>
and same mapping for data.
You entities should look like this:
public class Person
{
public Person()
{
DataCollection = new List<Data>();
}
public int PersonId { get; set; }
public string Name { get; set; }
public int DataId { get; set; }
public IList<Data> DataCollection{get;set;}
public void AddData(Data item)
{
if(!DataCollection.Contains(item))
{
DataCollection.Add(item);
}
}
}
public class Data
{
public int DataId { get; set; }
public string details { get; set; }
public Person Person{ get; set; }
}
This way you create a one-to-many relation from Person to Data. If you save your person entity after you added some data, the data will also be persisted. This depends on your cascade options offcourse.
I'm not sure how to map this with XML mappings, since i always use Fluent or Auto mappings.
This is a problem of unidirectional one-to-one mapping in NHibernate.
Student.cs
public class Student
{
public int ID { get; set; }
public int Roll { get; set; }
public int RegNo { get; set; }
public string Name { get; set; }
public StudentDetail StudentDetail { get; set; }
}
StudentDetail.cs
public class StudentDetail
{
public int ID { get; set; }
public string Father { get; set; }
public string Mother { get; set; }
}
How can I map these classes (how do the hbm mapping files look like) to the following case of one-to-one relationship?
Please have a look at the classes and the table very carefully.
Where can I put the <many-to-one> tag in Student.hbm.xml or StudentDetail.hbm.xml? If I put it in Student.hbm.xml, how can I map the column StudentDetail.StudentID, coz it is in a different table?
So this mapping:
<class name="Student" table="Student">
<id name="ID" column="ID">
<generator class="native"/>
</id>
.......
<many-to-one class="StudentDetail" name="StudentDetail" column="StudentID" unique="true" cascade="all" />
</class>
generates the following exception:
{"Invalid column name 'StudentID'."}
On the other hand <many-to-one> can't be placed in StudentDetail.hbm.xml. Coz, StudentDetail.cs doesn't contain any property of type Student.
Can I use <one-to-one>-tag? If yes where should I place it, in Student.cs or StudentDetail.cs? And how should I configure it?
Case #1:
In Student...
<one-to-one name="StudentDetail"
cascade="save-update,delete"
property-ref="Student" />
In StudentDetail...
<many-to-one name="Student"
column="StudentID"
unique="true"
cascade="none" />
Note that you'll have to have a property in your StudentDetail class that refers to a Student oobject (called Student). Also, your cascades might be different depending on your usage. You most likely want the delete cascade in there, though.
The unique="true" ensures the one-to-one mapping on the StudentDetail side.
Case #2:
Just exchange the two mappings, making sure you change the property names to the opposite class.
Look here for more info:
http://nhforge.org/blogs/nhibernate/archive/2009/04/19/nhibernate-mapping-lt-one-to-one-gt.aspx
You can map it as a one-to-many, with the collection property hidden and only its first element publicly exposed:
public class Student
{
public virtual int ID { get; set; }
public virtual int Roll { get; set; }
public virtual int RegNo { get; set; }
public virtual string Name { get; set; }
protected virtual IList<StudentDetail> StudentDetails { get; set; }
public virtual StudentDetail StudentDetail
{
get
{
if (StudentDetails.Count == 0) return null;
return StudentDetails[0];
}
set
{
if (StudentDetails.Count != 0) throw new Exception();
StudentDetails.Add(value);
value.Student = this;
}
}
}
You could handle the setter better than this - the point is to make sure you don't add multiple rows to the one-to-many. Obviously in this, StudentDetails is mapped but StudentDetail isn't in your .hbm.xml or Fluent mappings.
I am trying to map Users to each other. The senario is that users can have buddies, so it links to itself
I was thinking of this
public class User
{
public virtual Guid Id { get; set; }
public virtual string FirstName { get; set; }
public virtual string LastName { get; set; }
public virtual string EmailAddress { get; set; }
public virtual string Password { get; set; }
public virtual DateTime? DateCreated { get; set; }
**public virtual IList<User> Friends { get; set; }**
public virtual bool Deleted { get; set; }
}
But am strugling to do the xml mapping.
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyVerse.Domain"
namespace="MyVerse.Domain" >
<class name="User" table="[User]">
<id name="Id">
<generator class="guid" />
</id>
<property name="FirstName" />
<property name="LastName" />
<property name="EmailAddress" />
<property name="Password" />
<property name="DateCreated" />
<property name="Deleted" />
<set name="Friends" table="UserFriend">
<key foreign-key="Id"></key>
<many-to-many class="User"></many-to-many>
</set>
</class>
</hibernate-mapping>
something like
<bag name="Friends" table="assoc_user_table" inverse="true" lazy="true" cascade="all">
<key column="friend_id" />
<many-to-many class="User,user_table" column="user_id" />
</bag>
Consider using the repository pattern. Create a Repository contract and a base abstract class that takes one of your entities as a type (your mapped class)
Open the session when the repository is initialized and close when destroyed. (implement IDisposable).
Then make sure all of your access to the session happens within the using statement:
[pseudo-code]:
using(var repository = RepositoryFactory<EntityType>.CreateRepository())
{
var entity = repository.get(EntityID);
foreach (somesubclass in entity.subclasscollection)
{
//Lazy loading can happen here, session is still open with the repository
... Do Something
}
}
I use a base abstract class for my Repositories. This one is for my readonly repository but you'll get the drift. They key is to keep your units of work small, open the session only when you have something to do with the database, then let it close on the dispose. Here's the base class, disclaimer YMMV:
public interface IEntity
{
int Id { get; set; }
}
public interface IRORepository<TEntity> : IDisposable where TEntity : IEntity
{
List<TEntity> GetAll();
TEntity Get(int id);
}
public abstract class RORepositoryBase<T> : IRORepository<T> where T : IEntity
{
protected ISession NHibernateSession;
protected RORepositoryBase()
{
NHibernateSession = HibernateFactory.OpenSession();
NHibernateSession.DefaultReadOnly = true;
}
public ISession Session { get { return NHibernateSession; } }
public void Dispose()
{
NHibernateSession.Flush();
NHibernateSession.Close();
NHibernateSession.Dispose();
}
public virtual List<T> GetAll()
{
return NHibernateSession.Query<T>().ToList();
}
public virtual T Get(int id)
{
return NHibernateSession.Get<T>(id);
}
}
I have two classes:
public class Code
{
public virtual Guid CodeId { get; set; }
public virtual string CodeValue { get; set; }
public virtual Guid EntryId { get; set; }
}
public class Entry
{
public virtual Guid EntryId { get; set; }
public virtual string FirstName { get; set; }
public virtual string LastName { get; set; }
public virtual string Address { get; set; }
public virtual string Address2 { get; set; }
public virtual string City { get; set; }
public virtual string State { get; set; }
public virtual string Zip { get; set; }
public virtual string Email { get; set; }
public virtual string Phone { get; set; }
public virtual string IpAddress { get; set; }
public virtual DateTime BirthDate { get; set; }
public virtual DateTime Created { get; set; }
public virtual bool OptIn { get; set; }
public virtual Code Code { get; set; }
}
I want nhibernate to automatically load/save the Code child property of the Entry object (which can be null and is linked by a foreign key "EntryId" in the Codes table), but I cannot figure out the mapping. The documentation at hibernate.org isn't loading for me right now, so could someone point me in the right direction with the mappings below?
<class name="Code" table="Codes">
<id name="CodeId">
<generator class="guid.comb"/>
</id>
<property name="CodeValue" />
<property name="EntryId"
</class>
<class name="Entry" table="Entries">
<id name="EntryId">
<generator class="guid.comb"/>
</id>
<property name="FirstName" />
<property name="LastName" />
<property name="Address" />
<property name="Address2" />
<property name="City" />
<property name="State" />
<property name="Zip" />
<property name="Email" />
<property name="Phone" />
<property name="BirthDate" />
<property name="OptIn" />
<property name="IpAddress" />
<property name="Created" />
</class>
I believe this article describes the possibilities very well:
http://ayende.com/Blog/archive/2009/04/19/nhibernate-mapping-ltone-to-onegt.aspx
You just don't need to "simulate" the bidirectionality, but that's easy to leave out.