I have a one-to-many relationship and cannot get cascade to work, once I set cascade I just get "object references an unsaved transient instance ...".
My mapping looks like this
public class SharedDetailsMapping : ClassMap<SharedDetails>
{
public SharedDetailsMapping()
{
Id(x => x.Id).GeneratedBy.Identity();
HasMany(x => x.Foos);
}
}
public class FooMapping : ClassMap<Foo>
{
public FooMapping()
{
Id(x => x.Id).GeneratedBy.Identity();
References(x => x.SharedDetails).Cascade.SaveUpdate();
}
}
The classes like this
public class Foo
{
public Foo()
{
SharedDetails = new SharedDetails();
SharedDetails.Foos.Add(this);
}
public Foo(SharedDetails sharedDetails)
{
SharedDetails = sharedDetails;
SharedDetails.Foos.Add(this);
}
public virtual Guid Id { get; set; }
public virtual SharedDetails SharedDetails { get; set; }
}
public class SharedDetails
{
public SharedDetails()
{
Foos = new List<Foo>();
}
public virtual Guid Id { get; set; }
public virtual IList<Foo> Foos { get; set; }
}
I then want to create Foos without having to save the SharedDetails first if its a new Foo, like so:
using (var transaction = _session.BeginTransaction())
{
var shared = new SharedDetails();
var fooOne = new Foo(shared);
_session.SaveOrUpdate(fooOne);
var fooTwo = new Foo(shared);
_session.SaveOrUpdate(fooTwo);
transaction.Commit();
}
Cannot figure out what I have done wrong, it works ofcurse if I save the SharedDetails first but that is why I have Cascade setup.
In your SharedDetailsMapping, modify your HasMany to add .Inverse():
public class SharedDetailsMapping : ClassMap<SharedDetails>
{
public SharedDetailsMapping()
{
Id(x => x.Id).GeneratedBy.Identity();
HasMany(x => x.Foos)
.Inverse();
}
}
This instructs NHibernate that Foo owns the relationship, which will help it save objects in the relationship in the right order (in this case, the SharedDetails has to get saved first so we have its ID when Foo is saved).
Further info on the purpose/when to use Inverse: NHibernate's inverse - what does it really mean?
The TL;DNR version:
If you have a bidirectional relationship in your classes (HasMany on one side, References on the other), the HasMany should have .Inverse().
Related
I want to implement a one-to-many relationship between a person and car, and have CRUD operations on both person and car. Brief CRUD and relationships:
Update
A person has many cars
CRUD operations on both person and car via person object.
Deleting a person will delete all s/his cars
Ability to perform CRUD operation on someone's cars, either via person object or car object.
Is it possible via ORM, in particular NHibernate?
Classes like below:
public class PersonSet
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual ISet<CarSet> Cars { get; set; }
}
public class CarSet
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual PersonSet Person { get; set; }
}
Mapping is shown below:
public class PersonSetMap : ClassMapping<PersonSet>
{
public PersonSetMap()
{
Id(x => x.Id, m=>m.Generator(Generators.Identity));
Property(x=>x.Name);
Set(x => x.Cars, c =>
{
//c.Key(k =>
// {
// k.Column("PersonId");
// });
c.Cascade(Cascade.All);
c.Lazy(CollectionLazy.NoLazy);
// c.Inverse(true);
}
, r =>
{
r.OneToMany();
}
);
}
}
public class CarSetMap : ClassMapping<CarSet>
{
public CarSetMap()
{
Id(x => x.Id, m => m.Generator(Generators.Identity));
Property(x => x.Name);
ManyToOne(x => x.Person, m =>
{
m.Column("PersonId");
m.Cascade(Cascade.None);
m.NotNullable(true);
});
}
}
The problem I have is that if I update one car and try to save it on a person object, it doesn't change.
Update
I want to find out if it is possible, and where my mapping above is wrong. Any idea on either xml version or Loquacious would also be appreciated.
There should be a PersonId foreign key on table Car.
I don't know if this would solve your problem, but in a ManyToOne mapping the Unique and NotNullable methods should be applied at the column level.
ManyToOne(x => x.Person, m =>
{
m.Column(c =>
{
c.Name("PersonId");
c.NotNullable(true);
});
m.Cascade(Cascade.None);
});
This is a general question, I'm sure it's quite common, however I haven't found anything on it (or I don't know what to search for I guess).
I'm having the following entities in my project:
public class User
{
public virtual int Id { get; set; }
public virtual string FirstName { get; set; }
public virtual string LastName { get; set; }
public virtual Unit Unit { get; set; }
}
public class Unit
{
public virtual int Id { get; set;}
public virtual string Name { get; set;}
}
This is how I've done the Fluent NHibernate mappings:
public class UserMap : ClassMap<User>
{
public UserMap()
{
Id(x => x.Id).GeneratedBy.Identity().Column("UserId");
Map(x => x.FirstName);
Map(x => x.LastName);
References(x => x.Unit).Column("UnitId");
}
}
public class UnitMap : ClassMap<Unit>
{
public UnitMap()
{
Table("Unit");
LazyLoad();
Id(x => x.Id).GeneratedBy.Identity().Column("UnitId");
Map(x => x.Name).Column("Name").Not.Nullable();
HasMany(x => x.Users).KeyColumn("UnitId");
}
}
Now here is my question. How do I create a new User if I only have the user's unit Id not a full unit object, and the unit already exists in the database (created previously) ?
Something like this:
public class TestClass
{
// Adding a user to a unit example
public void SavingAUser(int unitId)
{
var user = new User
{
FirstName = "TestFirstName",
LastName = "TestLastName",
Unit = new Unit() // <-- I have only the Id of the unit I don't actually have a unit object here I don't want to query the DB to get the full object, I already have the Id
};
var userRepository = new UserRepository();
userRepository.Save(user);
}
}
How would I go about something like this. I hope I'm making sense, if not please let me know I'll throw in more clarifications. I'm also pretty certain that this is a very common scenario
You can return a proxy to the unit without fetching it.
var user = new User
{
FirstName = "TestFirstName",
LastName = "TestLastName",
Unit = Session.Load<Unit>(unitId)
}
You'll need to expose the session object.
I have an issue with mapping, simplified my relationship looks like this.
I have parent class:
public abstract class DocumentType
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
}
and two subclasses:
public class UploadedFileDocument : DocumentType
{
}
public class ApplicationFormDocument : DocumentType
{
}
mapped like this:
public DocumentTypeMap()
{
Schema("Core");
Id(x => x.Id);
Map(x => x.Name).Length(128).Not.Nullable();
DiscriminateSubClassesOnColumn("Type");
}
public class UploadedFileDocumentMap : SubclassMap<UploadedFileDocument>
{
}
public class ApplicationFormDocumentMap : SubclassMap<ApplicationFormDocument>
{
}
Then I have another entity with a FK to DocumentType, mapped like this:
public FileConversionMap()
{
Schema("Core");
Id(x => x.Id);
References(x => x.Application).Not.Nullable();
References(x => x.DocumentType).Not.Nullable().Fetch.Select();
}
my issue is, when I retrieve rows from the DB like this:
Session.Query<FileConversion>().AsQueryable();
all the rows come back with the DocumentType being of type DocumentType, not of the child type (ie the actual type of that property, ie. when i do .GetType(), either UploadedFileDocument or ApplicationFormDocument)
Apologies if this is just me being dim. But how can I determine which type of DocumentType I have ... is my mapping wrong?
When you look at your generated SQL (adding .ShowSQL() to your .Database method), do you see the Type being entered? You should see something similar to:
INSERT
INTO
"Core_DocumentType"
(Name, Type)
VALUES
(#p0, 'ApplicationFormDocument');
select
last_insert_rowid();
#p0 = 'afd' [Type: String (0)]
Using the mappings you provided, it looks fine and I could return the DocumentType (using SQLite) just fine.
Here's the code I used to reproduce it. I didn't have your FileConversion object, so please verify that it matches what you need.
DocumentType
public class DocumentType
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
}
public class DocumentTypeMap : ClassMap<DocumentType>
{
public DocumentTypeMap()
{
GenerateMap();
}
void GenerateMap()
{
Schema("Core");
Id(x => x.Id).GeneratedBy.Identity();
Map(x => x.Name).Length(128).Not.Nullable();
DiscriminateSubClassesOnColumn("Type");
}
}
UploadFileDocument/ApplicationFormDocument
public class UploadedFileDocument : DocumentType
{
public virtual string ContentType { get; set; }
}
public class ApplicationFormDocument : DocumentType
{
}
public class UploadFileDocumentMap :
SubclassMap<UploadedFileDocument>
{
public UploadFileDocumentMap()
{
GenerateMap();
}
void GenerateMap()
{
Map(x => x.ContentType);
}
}
public class ApplicationFormDocumentMap :
SubclassMap<ApplicationFormDocument>
{
}
FileConversion
public class FileConversion
{
public virtual int Id { get; set; }
public virtual DocumentType DocumentType { get; set; }
}
public class FileConversionMap : ClassMap<FileConversion>
{
public FileConversionMap()
{
GenerateMap();
}
void GenerateMap()
{
Schema("Core");
Id(x => x.Id).GeneratedBy.Identity();
References(x => x.DocumentType).Not.Nullable().Fetch.Select();
}
}
The tests I used (using machine.specifications):
Context
public class when_discriminating_on_subclass
{
static IList<FileConversion> results;
Establish context = () =>
{
using (var session = DataConfiguration.CreateSession())
{
using (var transaction = session.BeginTransaction())
{
var upload = new UploadedFileDocument
{ Name = "uploaded", ContentType = "test" };
var form = new ApplicationFormDocument
{ Name = "afd" };
session.Save(form);
session.Save(upload);
var formConversion =
new FileConversion { DocumentType = form };
var uploadConversion =
new FileConversion { DocumentType = upload };
session.Save(formConversion);
session.Save(uploadConversion);
transaction.Commit();
}
using (var transaction = session.BeginTransaction())
{
results = session.Query<FileConversion>().AsQueryable().ToList();
transaction.Commit();
}
}
};
Specifications
It should_return_two_results = () =>
results.Count.ShouldEqual(2);
It should_contain_one_of_type_uploaded_file = () =>
results
.Count(x => x.DocumentType.GetType() == typeof(UploadedFileDocument))
.ShouldEqual(1);
It should_contain_one_of_type_application_form = () =>
results
.Count(x => x.DocumentType.GetType() == typeof(ApplicationFormDocument))
.ShouldEqual(1);
}
Debugging through the assertions, I can see that the collection comes back with the two types:
Are you casting them back to the base type anywhere in your mappings or classes?
I have 2 classes that reference each other. It's a weird situation that our CRM needs.
I have an Organization and EmAddress tables and classes. The Organization inherits from Subscriber, which also has a table. I think this could be my problem, or the fact that I can't set Inverse on these because there is no "HasMany"...
The order of insert/update is ..
INSERT Email
INSERT Org
UPDATE Email to set Email.Subscriber
Email.Subscriber needs to be "NOT NULL", so this doesn't work. How can I change the order, I can't use Inverse because there is no list. Just 2 references.
public class Organization : Subscriber
{
public override string Class { get { return "Organization"; } }
EmAddress PrimaryEmailAddress {get;set;}
}
public class OrganizationMap : SubclassMap<Organization>
{
public OrganizationMap()
{
Table("Organization");
KeyColumn("Organization");
References(x => x.PrimaryEmail,"PrimaryEmailAddress").Cascade.SaveUpdate();
}
}
public EmAddressMap()
{
Id(x => x.Id, "EmAddress");
Map(x => x.EmailAddress, "eMailAddress");
References<Subscriber>(x => x.Subscriber,"Subscriber").LazyLoad().Fetch.Select().Not.Nullable();
/*not.nullable() throw s error. NHibernate INSERTS email, INSERTS org, UPDATES email. */
}
public class EmAddress
{
public virtual Guid Id { get; set; }
public virtual string EmailAddress { get; set; }
public virtual Subscriber Subscriber { get; set; }
}
//Implementation
var session = NHIbernateHelper.GetSession();
using(var tx = session.BeginTransaction())
{
var org = new Organization();
org.PrimaryEmail = new EmAddress(){Subscriber = org};
session.Save(org);
tx.commit();
}
This post might help:
http://ayende.com/blog/3960/nhibernate-mapping-one-to-one
Have only one side use many-to-one (Fluent: "References") and the other side uses one-to-one (Fluent: "HasOne").
I'm confused by the following NHibernate behaviour:
Domain classes and mappings:
public class Category
{
public virtual int ID { get; set; }
public virtual string Name { get; set; }
private IList<Product> _products;
public virtual IList<Product> Products
{
get { return new List<Product>(_products).AsReadOnly(); }
}
public Category()
{
_products = new List<Product>();
}
}
public class Product
{
public virtual int ID { get; set; }
public virtual string Name { get; set; }
public virtual Category Category { get;set; }
}
public class ProductMap : ClassMap<Product>
{
public ProductMap()
{
Schema("dbo");
Table("tProducts");
Id(x => x.ID);
Map(x => x.Name);
References(x => x.Category).Column("CategoryID");
}
}
public class CategoryMap : ClassMap<Category>
{
public CategoryMap()
{
Schema("dbo");
Table("tCategories");
Id(x => x.ID);
Map(x => x.Name);
HasMany(x => x.Products)
.KeyColumn("CategoryID")
.Access.CamelCaseField(Prefix.Underscore)
.Inverse()
.Cascade.All();
}
}
Code causing trouble:
Category category;
using (var session = sessionFactory.OpenSession())
{
category = session.Get<Category>(1);
}
using (var session = sessionFactory.OpenSession())
{
var products = category.Products; // exception
}
Why do I get no session exception when I'm trying to get products? I've got a session here! How to avoid this exception (I prefer 2 sessions here, and I want to keep loading lazy)?
Thanks in advance!
Can you re-attach the object to your new session either:
ISession.Update(myDetachedInstance);
or, if the object has not been changed:
ISession.Lock(myDetachedInstance, NHibernate.LockMode.None);
For more info, see: http://intellect.dk/post/Detached-objects-in-nHibernate-and-Lazy-loading.aspx
I got this same error and it was due to the WPF UI holding on to references to objects from the old nhibernate session after I clicked the "refresh" button which called refresh on the data context which disassociated all cached objects in the session.
I needed to make sure "NotifyChange" was being fired to make the UI update (and that the UI was listening to it).