Database Strucutre:
Shows
ID
Name
Genres
ID
Name
ShowsGenres
ShowsID
GenresID
Above is my Database I am trying to figure out how to map this properly. My Show object is like this:
public class Show
{
public virtual int ID { get; set; }
public virtual string Name { get; set; }
public virtual IList<Genre> Genres { get; set; }
}
My Genre Object is:
public class Genre
{
public virtual int ID { get; set; }
public virtual string Name { get; set; }
public virtual IList<Show> Shows { get; set; }
}
I have tried several different varations of HasManyToMany, but none work the way I want them to.
I need to be able to delete a show and the relationship with the genre, or many genres, but not delete the genre(s).
I need to be able to delete a genre and its relationship with a show, or many shows, but not delete the show(s).
How can I map this or do I need to try something differently?
Update: Also thinking about it more I would also need to be able to remove the relationship between a show and a genre without removing the show or the genre.
Here are my mappings I have, but not exactly sure they are correct.
HasManyToMany<Genre>(x => x.Genres)
.Table("ShowGenres")
.ParentKeyColumn("ShowID")
.ChildKeyColumn("GenreID");
HasManyToMany<Show>(x => x.Shows)
.Table("ShowGenres")
.ParentKeyColumn("GenreID")
.ChildKeyColumn("ShowID");
This is an old post but I basically had the same question. Answered here:
HasManyToMany Fluent NHibernate Mapping Delete Error
Related
I'm having issues with Nhibernate persisting a HasOne Relationship for one of my entities with Cascade.None() in effect. My domain model involves 4 classes listed below.
public class Project
{
public virtual int Id {get;set;}
public virtual IList<ProjectRole> Team { get; protected set; }
}
public class ProjectRole
{
public virtual int Id { get; set; }
public virtual User User { get; set; }
public virtual Role Role { get; set; }
}
public class Role
{
public virtual int Id { get; set; }
public virtual string Value { get; set; }
}
public class User
{
public virtual int Id { get; protected set; }
public virtual string LoginName { get; set; }
}
So basically we have projects, which have a list of ProjectRoles available from the Team property. Each ProjectRole links a User to the specific Role they play on that project.
I'm trying to setup the following cascade relationships for these entities.
project.HasMany<ProjectRoles>(p=> p.Team).Cascade.All()
projectRole.HasOne<Role>(r => r.Role).Cascade.None()
projectRole.HasOne<User>(r => r.User).Cascade.SaveUpdate()
I've used fluent nhibernate overrides to setup the cascades as above, but I'm finding that the line
projectRole.HasOne<Role>(r => r.Role).Cascade.None()
is resulting in the ProjectRole.Role property not being saved to the database. I've diagnosed this be looking at the SQL Generated by Nhibernate and I can see that the "Role_id" column in the ProjectRoles table is never set on update or insert.
I've also tried using
projectRole.HasOne<Role>(r => r.Role).Cascade.SaveUpdate()
but that fails as well. Unfortunately leaving it Cascade.All() is not an option as that results in the system deleting the Role objects when I try to delete a project role.
Any idea how to setup Cascade.None() for the ProjectRole-> Role relationship with out breaking persistence.
HasOne is for a one-to-one relationship which are rare. You want to use References to declare the one side of a one-to-many relationship. Making some assumptions about your domain model, the mapping should look like:
project.HasMany<ProjectRoles>(p=> p.Team).Inverse().Cascade.AllDeleteOrphan()
projectRole.References<Role>(r => r.Role);
projectRole.References<User>(r => r.User);
See also this question about the difference between HasOne and References.
I am attempting to use NHibernate to generate a model for a very odd database. The tables themselves have primary keys for show only, all the actual relationships are on unique columns. For example, a product table with a product id primary key and a unique product name column. Another table, demand, has a product name column and that defines the relationship. I know this situation isn't ideal but it's out of my control.
At any rate, I was able to use Fluent NHibrenate to map product to demand, but I cannot seem to get the entity to lazy-load.
public class Demand
{
public virtual DemandId { get; set; }
public virtual Product { get; set; }
}
public class DemandMap : ClassMap<Demand>
{
public DemandMap()
{
this.Table("Demand");
this.LazyLoad();
this.Id(x => x.DemandId);
this.References(x => x.Product).PropertyRef(x => x.ProductName).LazyLoad();
}
}
Does anyone have any insight into why lazy loading is not working? I know it is not because I can see the product being fetched along with the demand in the SQL profiler.
My idea (Maybe you can try use "HasMany" there is example but you can read something about this):
First class
public class Demand
{
public virtual int DemandId { get; set; }
public virtual int Product { get; set; }
public virtual IEnumerable<NewClass> Name {get; set;}
}
this.HasMany(x=> x.Product).Column("Product_id").not.nullable;
Second class
public class NewClass
{
public virtual Demand Product_id {get; set;}
}
this.References(x => x.Product).Column("product_id).not.nullable
Fluent Nhibernate Many to Many association to multiple classes
We use Nhibernate and up to now we have been able use the auto mapping. But I think this is about to change.
We have a Code class that has a many to many relation with several other classes.
I’m thinking something along these lines:
public class Code
{
public virtual Guid Id { get; set; }
public virtual ICollection<CodeUsage> Usage { get; set; }
}
class CodeUsage
{
public virtual Guid Id { get; set; }
public virtual Code Code { get; set; }
// Class, [Property,] Id for "ANY" mapping to A & B
}
class A
{
public virtual Guid Id { get; set; }
public virtual ICollection<CodeUsage> Codes { get; set; }
}
class B
{
public virtual Guid Id { get; set; }
public virtual ICollection<CodeUsage> Codes { get; set; }
}
Many to Many will lead to the creation of a linking table, in the linking table their needs come a mapping to the classes using codes. In the documentation it is referred to as a “Any” mapping.
But I have no idea how get fluent to create one.
Thoughts anyone? or even better: a solution <);o)}{
You can't map <many-to-any> in Fluent NHibernate - it's not supported.
I think it may be a good reason to move to mapping-by-code, that supports it well.
I'm having trouble getting the Fluent Nhibernate Automapper to create what I want. I have two entities, with a one-to-many relationship between them.
class Person
{
public string name;
IList<departments> worksIn;
}
class Department
{
public string name;
}
The above is obviously bare bones, but I would be expecting to generate the fleshed out schema of:
Person{id, name}
Department{id, name}
PersonDepartment{id(FK person), id(Fk Department)}
Unfortunately, I am instead getting:
Person{id, name}
Department{id, name, personid(FK)}
I don't want the FK for Person included on the department table, I want a separate join/lookup table (PersonDepartment above) which contains the primarykeys of both tables as a composite PK and also Fks.
I'm not sure if I am drawing up my initial classes wrong (perhaps should just be LIst workIn - representing ids, rather than List worksIn), or if I need to manually map this?
Can this be done?
The way the classes have been structured suggests a one-to-many relationship (and indeed that's how you describe it in your question), so it should not be a surprise that FNH opts to model the database relationship in that way.
It would be possible, as you suggest, to manually create a many-to-many table mapping. But, is this definitely what you want?
I tend to find that pure many-to-many relationships are quite rare, and there is usually a good case for introducing an intermediate entity and using two one-to-many relationships. This leaves open the possibility of adding extra information to the link (e.g. a person's "primary" department, or perhaps details of their office within each of their departments).
Some example "bare-bones" classes illustrating this kind of structure:
public class Person
{
public int Id { get; set;}
public string Name { get; set;}
public IList<PersonDepartment> Departments { get; set; }
}
public class PersonDepartment
{
public int Id { get; set; }
public Person Person { get; set; }
public Department Department { get; set; }
public bool IsPrimary { get; set; }
public string Office { get; set; }
}
public class Department
{
public int Id { get; set; }
public IList<PersonDepartment> Personnel { get; set; }
public string Name { get; set; }
}
I'm having some trouble figuring out the appropriate FluentNHibernate mapping syntax for the following data model and domain objects. Here's the data model I'm working against:
And I'm trying to map the following domain objects to that model:
namespace FluentNHibernateSandbox.Entities
{
public abstract class EntityBase
{
public virtual long Id { get; set; }
}
}
namespace FluentNHibernateSandbox.Entities
{
public class Attribute : EntityBase
{
public virtual string Name { get; set; }
public virtual string Label { get; set; }
public virtual string Description { get; set; }
public virtual int SortOrder { get; set; }
public virtual Group Group { get; set; }
public virtual Editor Editor { get; set; }
}
}
namespace FluentNHibernateSandbox.Entities
{
public class Group : EntityBase
{
public virtual string Name { get; set; }
public virtual string Label { get; set; }
public virtual string Description { get; set; }
public virtual int SortOrder { get; set; }
public virtual IList<Attribute> Attributes { get; set; }
}
}
namespace FluentNHibernateSandbox.Entities
{
public class Editor : EntityBase
{
public virtual string ViewName { get; set; }
public virtual string WorkerClassName { get; set; }
}
}
In general, what I ultimately want doesn't seem like it should be all that hard to do, but I after having tried just about every combination of mappings I can think of, I still can't seem to get it right. I just need my Attribute to have a reference to the Group that it belongs to and a reference to the Editor assigned to it, and each Group should have a collection of the Attributes that are part of it. The couple of many-to-many join tables are what seem to be giving me fits. Particularly the APPLICATION_ATTRIBUTE table. Ultimately I only want the Attributes that my application is concerned with, in this case, those with an APPLICATION_ID of 4.
Any help would be greatly appreciated. Thanks.
Really kinda surprised nobody responded to this at all, but anyway. The answer/solution for this mapping situation that we came up with, which I was trying to avoid to start with, but turned out to really be the best way to go, was to create some custom views in the database that joined together all of the application-specific data I needed, and then just mapped my application's domain objects to those views. This worked at least partially because the information I needed from these tables is going to be read-only for this application, but even if I needed to write to the tables, I'm pretty sure (though haven't verified as I didn't really have need in this case) that I could have setup my views to be writeable and that would've worked too.
Hat tip to #robconery.