I have the following schema, and when I delete one of the objects on one many side, it seems to be trying to delete the objects on the other many side. Am somewhat confused about the proper Cascade options to use, and I don't find Oren's brief description of them to be useful, so please don't quote those back.
public class Store {
public virtual IList<StoreProduct> StoreProducts { get; set; }
}
public class Product {
public virtual IList<StoreProduct> StoreProducts { get; set; }
}
public class StoreProduct {
public virtual Store Store { get; set; }
public virtual Product Product { get; set; }
public virtual Decimal Cost { get; set; } //this is why I have a custom linking class
}
In my mapping overrides, I have:
For Store:
mapping.HasMany(x => x.StoreProducts).Cascade.AllDeleteOrphan().Inverse;
For Product:
mapping.HasMany(x => x.StoreProducts).Cascade.AllDeleteOrphan().Inverse;
When I try to delete a Store that has associated StoreProducts, it seems that NHIbernate tries to delete not only the StoreProducts, but the Products.
Here are my conventions:
return c =>
{
c.Add<ForeignKeyConvention>();
c.Add<HasManyConvention>();
c.Add<HasManyToManyConvention>();
c.Add<ManyToManyTableNameConvention>();
c.Add<PrimaryKeyConvention>();
c.Add<ReferenceConvention>();
c.Add<EnumConvention>();
c.Add<TableNameConvention>();
c.Add<CascadeAll>();
c.Add(DefaultCascade.All());
};
HasManyConvention:
public void Apply(IOneToManyCollectionInstance instance)
{
instance.Key.Column(instance.EntityType.Name + "Fk");
instance.Cascade.AllDeleteOrphan();
instance.Inverse();
}
What am I doing wrong?
Thanks!
p.s.: I don't want to overwhelm people w/code, but can post more if needed.
Thanks, CrazyDart - I think that is among the things I tried without success. What I ended up doing was adding a StoreProducts override that looks like this:
public class StoreProductOverride: IAutoMappingOverride<StoreProduct>
{
#region IAutoMappingOverride<StoreProduct> Members
public void Override(AutoMapping<IndicatorStrategy> mapping)
{
mapping.References(x => x.Store).ForeignKey("StoreFk").Cascade.SaveUpdate();
mapping.References(x => x.Producty).ForeignKey("ProductFk").Cascade.SaveUpdate();
}
#endregion
}
Seems to work, but QA hasn't tried to break it yet (-:
You need to turn off the cascading on StoreProduct is my guess. Its hard to test without setting it up. I see the cascade on Store and Product, but turn it off on StoreProduct.
Related
I had to define a recursive relationship on a composite key. After much trials, I ended up with this:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Category>()
.Property(t => t.WhichAmazon).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
modelBuilder.Entity<Category>()
.Property(t => t.IdCategory).HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);
modelBuilder.Entity<Category>()
.HasKey(c => new {c.WhichAmazon, c.IdCategory})
.HasOptional(p => p.Children)
.WithMany()
.HasForeignKey(c => new { c.WhichChildrenAmazon, c.ChildrenId });
}
for this table
public class Category
{
// Keys and relationships defined in BooksDataLayer
[MaxLength(2)]
public string WhichAmazon { get; set; }
public int IdCategory { get; set; }
public string Name { get; set; }
[Timestamp]
public Byte[] TimeStamp { get; set; }
public DateTime LastCheck { get; set; }
public virtual List<Book> Books { get; set; }
public string WhichChildrenAmazon { get; set; }
public int? ChildrenId { get; set; }
public virtual List<Category> Children { get; set; }
}
While trying to Add-Migration I was constantly having the same error: "Sequence contains no elements". As I was "almost" sure this definition was right, I went ahead a re-created a new Db, WITHOUT migration. Was perfectly OK, no problems with the Db at all. So there is "something" in there which EF 6 does not like. I had a confirmation, as EF power tools bombs if I try to get a schema "Exception has been thrown by the target of an invocation".
I'll see what happens now with migration if I restart from there, but I am afraid to not be able to use anymore with this Db. I do like the tool, a lot, so I hope this can be fixed.
The issue is an invalid configuration of the relationship.
The Fluent API call includes this:
.HasOptional(p => p.Children)
.WithMany()
This is invalid because Children is a collection navigation. The correct config is:
.HasMany(p => p.Children)
.WithOptional()
We are planning to take a fix to provide a better exception message post-EF6.
Opened a bug for this on the EF codeplex site: http://entityframework.codeplex.com/workitem/1015
I'm using fluent hibernate 1.2.0.712 and nhibernate 3.2.0.4000 in my mvc project as an OR mapper, the problem is :
this is my oJob object:
public class Job{
virtual public Enquiry Enquiry { get; set; }
virtual public long Id { get; set; }
}
and this is Enquiry:
public class Enquiry {
virtual public long Id { get; set; }
}
and here is JobMap:
public class JobMap: ClassMap<Job>
{
public JobMap()
{
Schema("dbo");
Id(p => p.Id)
.Column("Id");
References(p => p.Enquiry);
}
}
i expect that each job has exactly one enquiry
but sometimes that i check sql server i see there are some records in job table with different ids that all have the same enquiryid
and i checked it many times and dont know when exactly it happens, what is the problem?
You must change your mapping : change
References(p => p.Enquiry);
by
HasOne(p => p.Enquiry);
I have the following database tables defined:
Club: Id, Name
Member: Id, Name
ClubMember: ClubId, MemberId
I have the following entity Classes defined:
public class Club() {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual IList<Member> Members { get; set; }
}
public class Member() {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual IList<Club> Clubs { get; set; }
}
I have the following overrides defined:
public class MemberOverride : IAutoMappingOverride<Member>
{
public void Override(AutoMapping<Member> mapping_)
{
mapping_
.HasManyToMany(x_ => x_.Clubs)
.ParentKeyColumn("MemberId")
.ChildKeyColumn("ClubId")
.Cascade.All()
.Table("ClubMembers");
}
}
public class ClubOverride : IAutoMappingOverride<Club>
{
public void Override(AutoMapping<Club> mapping_)
{
mapping_
.HasManyToMany(x_ => x_.Members)
.ParentKeyColumn("ClubId")
.ChildKeyColumn("MemberId")
.Inverse()
.Table("ClubMembers");
}
}
I can see from my overrides that the Inverse on the ClubOverride means you cannot do the following
session.Save(club.Members.Add(member));
but this works:
session.Save(member.Clubs.Add(club);
But it doesn't make logical sense. I want to be able to save either the club with members or member with clubs.
Am I trying to do something impossible with FluentNhibernate?
TIA
Yes, you're right, that's not possible. But it's not a question of FluentNhibernate, NHibernate works like that.
Only one side is the owner of the relation and on charge of adding elements.
From official documentation:
Changes made only to the inverse end of the association are not persisted. This means that NHibernate has two representations in memory for every bidirectional association, one link from A to B and another link from B to A. This is easier to understand if you think about the .NET object model and how we create a many-to-many relationship in C#:
You can create add or remove methods on your entities that will help accomplish this:
public class Club() {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
private IList<Member> members;
public virtual IEnumerable<Member> Members { get { return members.Select(x => x); } }
public Club() {
members = new List<Member>();
}
public virtual void AddMember(Member member){
if (members.Contains(member))
return;
members.Add(user);
member.AddClub(this);
}
public virtual void RemoveMember(Member member){
if (!members.Contains(member))
return;
members.Remove(member);
member.RemoveClub(this);
}
}
Currently in my entities I'm exposing my collections as an IList but I've been thinking about exposing them as a IEnumerable to prevent users from manually adding to the collections. I have specific adds for these operations so that I can make sure my bi-directional relationships stay intact. A couple questions come to mind in this scenario.
If I expose them as IEnumberable does this mean I'll need an Add and Remove method for every collection that represents a relationship in my entities?
Is there an easier way to do this? I'm not against doing it this way just wondering.
Are you doing it this way?
Example:
public class OrderHeader
{
public virtual Guid OrderId { get; private set; }
public virtual IList<OrderLine> OrderLines { get; set; }
public virtual void AddLine(OrderLine orderLine)
{
orderLine.Order = this;
OrderLines.Add(orderLine);
}
//No need for a remove method since we expose collection as IList
}
Converting the class above so that we only expose IEnumerable would result in:
public class OrderHeader
{
public virtual Guid OrderId { get; private set; }
private IList<OrderLine> orderLines { get; set; }
public IEnumerable<OrderLine> OrderLines { get { return orderLines; } }
public virtual void AddLine(OrderLine orderLine)
{
orderLine.Order = this;
orderLines.Add(orderLine);
}
public virtual void RemoveLine(OrderLine orderLine)
{
orderLines.Remove(orderLine);
}
}
Yes, if you expose an IEnumerable it is best to add methods on the class to handle Add/Remove
A private backing field is a pretty good solution.
Yes, but keep in mind if you want truly read only access to the exposed collection use ReadOnlyCollection - http://msdn.microsoft.com/en-us/library/ms132474.aspx
Agreed with Dan's answer, with a minor change:
public IEnumerable<OrderLine> OrderLines
{ get { return orderLines.Select(x => x; } }
I need to persist this class on database using Fluent NHibernate:
public class RaccoonCity
{
public virtual int Id { get; private set; }
public virtual DateTime InfectionStart { get; private set; }
private IList<Zombie> _zombies = new List<Zombie>();
public virtual IEnumerable<Zombie> Zombies
{
get { return _zombies; }
}
protected RaccoonCity()
{}
public RaccoonCity(DateTime startMonth)
{
InfectionStart = startMonth;
}
public virtual void AddZombie(Zombie z)
{
_zombies.Add(z);
}
}
The property has type IEnumerable to indicate that you shouldn´t use it to insert new items. The backing field is of IList to make it easy to insert new items from the own class.
Zombie is a simple class:
public class Zombie
{
public virtual int Id { get; private set; }
public virtual string FormerName { get; set; }
public virtual DateTime Infected { get; set; }
}
The map is the following:
public class RaccoonCityMap: ClassMap<RaccoonCity>
{
public RaccoonCityMap()
{
Id(x => x.Id);
Map(x => x.InfectionStart);
HasMany(x => x.Zombies)
.Access.CamelCaseField(Prefix.Underscore)
.Inverse()
.Cascade.All();
}
}
When I test this, the data is inserted in database, but the zombie´s foreign keys are empty, and the RaccoonCity instance has zero items on Zombies list.
You are declaring the relationship as Inverse, which means the Zombie and not the RacoonCity is responsible for maintaining the relationship.
Either add the corresponding reference to zombie and set it on the AddZombie method, or remove the Inverse (in that case, you'll see an INSERT with a null FK followed by an update).
Suggested reading: http://nhibernate.info/doc/nh/en/index.html#collections-onetomany
Found a post about it: https://web.archive.org/web/20090831052429/http://blogs.hibernatingrhinos.com/nhibernate/archive/2008/08/15/a-fluent-interface-to-nhibernate-part-3-mapping.aspx
I had to implement the method
HasManyComponent by myself since it
was missing in the actual trunk of the
framework. That is, it was not
possible to map a collection of value
objects. But it has not been that hard
since the source base is really nice.
My changes will probably be integrated
into the framework soon.
And this one:
http://nhforge.org/blogs/nhibernate/archive/2008/09/06/a-fluent-interface-to-nhibernate-part-3-mapping-relations.aspx