I am getting NHibernate.MappingException while trying to do one-to-many mapping in fluent nhibernate.
Below are the snippets from my entity and their mapping classes:
public class ReportRequest : IReportRequestToBeFullyLoaded
{
public virtual Int32? Id { get; set; }
public virtual string Description { get; set; }
public virtual ISet<ReportOutputEmail> ReportOutputEmails { get; set; }
}
public class ReportOutputEmail
{
public virtual string RecipientAddress { get; set; }
public virtual string Message { get; set; }
public virtual ReportRequest ReportRequest { get; set; }
}
public class ReportRequestMap : ClassMap<ReportRequest>
{
public ReportRequestMap()
{
Table("ReportRequest");
Id(x => x.Id).UnsavedValue(null).GeneratedBy.Native();
Map(x => x.Description);
HasMany(x => x.ReportOutputEmails).Table("ReportOutputEmail")
.ForeignKeyConstraintName("FK_ReportOutputEmail_ReportRequest")
.KeyColumn("ReportRequestId")
.AsSet()
.Inverse()
.Cascade.AllDeleteOrphan();
}
}
public class ReportOutputEmailMap: ClassMap<ReportOutputEmail>
{
public ReportOutputEmailMap()
{
References(x => x.ReportRequest)
.ForeignKey("FK_ReportOutputEmail_ReportRequest")
.Column("ReportRequestId");
Map(x => x.RecipientAddress);
Map(x => x.Message);
}
}
There is some issue with one-to-many mapping between ReportRequest->ReportOutputEmail,
Getting error:
Error: NHibernate.MappingException: (XmlDocument)(3,6): XML validation error: The
element 'class' in namespace 'urn:nhibernate-mapping-2.2' has invalid child element
'property' in namespace 'urn:nhibernate-mapping-2.2'. List of possible elements expected: 'meta, subselect, cache, synchronize, comment, tuplizer, id, composite-id' in namespace 'urn:nhibernate-mapping-2.2'.
Can anyone help figuring out.
Thank you!
Your ReportOutputEmail doesn't have an identity, it'll need one if its going to be an entity.
Also, I recommend you upgrade your copy of Fluent NHibernate, as this is reported in a much more helpful manner since 1.1 (you'd get an identity missing message).
Related
I'm having a problem with NHibernate querying the database way too many times. I just realized it likely relates to the n+1 problem but I can't figure out how to change my mappings to solve the problem.
As you will see, my attempts involve specifying not to lazy load other objects, but it doesn't seem to do the trick.
This is the query:
public IQueryable<Report> ReadAll(DateTime since)
{
return m_session.QueryOver<Report>()
.JoinQueryOver(r => r.Mail)
.Where(m => m.Received >= since)
.List()
.AsQueryable();
}
Thanks in advance for any response! If you need any more information about my objects or mappings, please let me know.
Simplified objects graph (some omitted):
public class Report : EntityBase
{
public virtual Product Product { get; set; }
public virtual StackTrace StackTrace { get; set; }
public virtual Mail Mail { get; set; }
public virtual IList<ClientUser> ReadBy { get; set; }
}
-
public class Product : EntityBase
{
public virtual string Name { get; set; }
public virtual Version Version { get; set; }
public virtual IList<Report> Reports { get; set; }
public virtual IList<StackTrace> StackTraces { get; set; }
}
-
public class StackTrace : EntityBase
{
public virtual IList<StackTraceEntry> Entries { get; set; }
public virtual IList<Report> Reports { get; set; }
public virtual Product Product { get; set; }
}
Mapping examples:
public class ReportMap : ClassMap<Report>
{
public ReportMap()
{
Table("Report");
References(x => x.User)
.Column("EndUserId")
.Not.LazyLoad();
References(x => x.Product)
.Column("ProductId")
.Not.LazyLoad();
References(x => x.StackTrace)
.Column("StackTraceId")
.Not.LazyLoad();
HasManyToMany(x => x.ReadBy)
.Cascade.SaveUpdate()
.Table("ClientUserRead")
.ParentKeyColumn("ReportId")
.ChildKeyColumn("ClientUserId")
.Not.LazyLoad().BatchSize(200);
}
}
-
public class StackTraceMap : ClassMap<StackTrace>
{
public StackTraceMap()
{
Table("StackTrace");
References(x => x.Product)
.Column("ProductId");
HasMany(x => x.Entries)
.KeyColumn("StackTraceId")
.Not.LazyLoad()
.Cascade
.All().BatchSize(500);
HasMany(x => x.Reports)
.KeyColumn("StackTraceId")
.Inverse().BatchSize(100);
}
}
The way to go is to use batch fetching. Read more about it here:
How to Eager Load Associations without duplication in NHibernate?
On every entity mapping apply BatchSize (for many-to-one relation - avoiding 1 + N)
public ReportMap()
{
Table(...)
BatchSize(25);
...
And on every collection (solves issue with one-to-many 1 + N)
HasMany(x => x.Reports)
.KeyColumn("StackTraceId")
.BatchSize(25)
...
You can specify fetch paths in the query. For example, this fetch path can tell the query to eagerly join product and main objects, as well as an imaginary association on the collection of clients:
public IQueryable<Report> ReadAll(DateTime since)
{
return m_session.QueryOver<Report>()
.JoinQueryOver(r => r.Mail)
.Where(m => m.Received >= since)
.Fetch(x => x.Product).Eager
.Fetch(x => x.Mail).Eager
.Fetch(x => x.ReadBy.First().SomeProp).Eager
.List()
.AsQueryable();
}
If you want that always to happen, try using .Fetch.Join() instead of .Not.LazyLoad() for the assocations. But I would not recommend that because it can cause simple queries to become huge. Batching or subqueries can help too.
I have the following classes:
public class Track
{
public virtual int Id { get; set; }
public virtual Track MainMix { get; set; }
public virtual IEnumerable<Track> SubMixes { get; set; }
public virtual IList<FileVersion> Files { get; set; }
}
public class FileVersion
{
public virtual int Id { get; set; }
public virtual Track Track { get; set; }
}
And the following mappings:
public class TrackMap : ClassMap<Track>
{
public TrackMap()
{
Id(x=>x.Id);
References(x => x.MainMix);
HasMany(x => x.SubMixes)
.Inverse()
.Cascade.All()
.KeyColumn("MainMix_id");
HasMany(a => a.Files)
.Access.CamelCaseField(Prefix.Underscore)
.Cascade.All();
}
}
public class FileVersionMap : ClassMap<FileVersion>
{
public FileVersionMap()
{
Id(x => x.Id);
References(x => x.Track);
}
}
There is omitted code for the sake of simplicity. The Track table has a "MainMix_id" column that is a self referencing column for a parent/child relationship among Track records.
When I try to fetch a track from the database the NHProfiler tells me that Nhibernate tries to fetch the fileversions of that track with the following query:
SELECT files0_.MainMix_id as MainMix9_1_,
files0_.Id as Id1_,
files0_.Id as Id9_0_,
files0_.Track_id as Track8_9_0_
FROM [FileVersion] files0_
WHERE files0_.MainMix_id = 3 /* #p0 */
It seems like it has confused the parent id column of the Track table with its primary key column. When I remove References(x => x.MainMix) from the Track mapping the query is correct, but I don't have the parent track record returned.
Let me know if I can clarify this any more and thanks in advance for your help!
Does this make a difference?
TrackMap :
References(x => x.MainMix).Column("MainMix_id");
FileVersionMap :
References(x => x.Track).Column("Track_id");
I attempted to extract some common properties to a base class and map with Fluent Nhibernate. In addition, I also attempted to add a second level of inheritance.
//Base entity class
public class EntityBase : IEntityBase
{
public EntityBase()
{
CreatedDate = DateTime.Now;
}
public virtual DateTime? CreatedDate { get; set; }
public virtual int Id { get; set; }
public virtual int Version { get; set; }
}
//Base Entity Mapping
public class EntityBaseMap: ClassMap<EntityBase>
{
public EntityBaseMap()
{
UseUnionSubclassForInheritanceMapping();
Id(x => x.Id);
Version(x => x.Id);
Map(x => x.CreatedDate);
}
}
//first sub class of EntityBase
public class Actuate : EntityBase, IActuate
{
public virtual DateTime? ActivatedOn { get; set; }
}
//Actuate Mapping class
public class ActuateMap : SubclassMap<Actuate>
{
public ActuateMap()
{
Map(x => x.ActivatedOn);
}
}
//Sub class entity
public class Item : Actuate
{
public virtual string Name { get; set; }
public virtual string Description { get; set; }
public virtual decimal UnitPrice { get; set; }
public virtual ItemStatus Status { get; set; }
public virtual Store Store { get; set; }
}
//Item Mapping class
public class ItemMap : SubclassMap<Item>
{
public ItemMap()
{
Abstract();
Map(x => x.Name);
Map(x => x.Description);
Map(x => x.UnitPrice);
Map(x => x.Status);
References(x => x.Store);
}
}
The entity I have discovered has a problem (other relationship issues might exists)
//Store entity Does not inherit from EntityBase or Actuate
public class Store
{
public virtual int Id { get; set; }
public virtual int Version { get; set; }
public virtual string Name { get; set; }
public virtual IEnumerable<Item> Items { get; set; }
}
//Store mapping class
public class StoreMap : ClassMap<Store>
{
public StoreMap()
{
Id(x => x.Id).GeneratedBy.Assigned();
Version(x => x.Version);
Map(x => x.Name);
HasMany(x => x.Items);
}
}
Problem
If I try to run the following query:
//store = is the Store entity I have retrieved from the database and I am trying
//trying to return the items that are associated with the store and are active
store.Items != null && store.Items.Any(item => item.Status == ItemStatus.Active);
I get the following error:
ERROR
Nhibernate.Exceptions.GenericADOException: could not initialize a collection: [SomeDomain.Store.Items#0][SQL: SELECT items0_.StoreId as StoreId1_, items0_.Id as Id1_, items0_.Id as Id10_0_, items0_.CreatedDate as CreatedD2_10_0_, items0_.ActivatedOn as Activate1_11_0_, items0_.Name as Name12_0_, items0_.Description as Descript2_12_0_, items0_.UnitPrice as UnitPrice12_0_, items0_.Status as Status12_0_, items0_.StoreId as StoreId12_0_ FROM [Item] items0_ WHERE items0_.StoreId=?]"}
Inner Exception
"Invalid object name 'Item'."
Now, if I take out the base classes and Item doesn't inherit, and the
Id, Version
columns are part of the Item entity and are mapped in the ItemMap mapping class (with the ItemMap class inheriting from ClassMap<Item> instead, everything works without issue.
NOTE
I have also attempted to add on the StoreMap class unsuccessful.
HasMany(x => x.Items).KeyColumn("Id");
Any thoughts?
if entityBase is just for inheriting common properties then you do not need to map it at all
public class EntityBaseMap<TEntity> : ClassMap<TEntity> where TEntity : EntityBase
{
public EntityBaseMap()
{
Id(x => x.Id);
Version(x => x.Version);
Map(x => x.CreatedDate);
}
}
public class ActuateMap : EntityBaseMap<Actuate> { ... }
Notes:
Versionmapping should map Version property not Id
Version should be readonly in code so nobody accidently alters it
.KeyColumn("Id") is wrong because the column is from the Items table and then it's both the autogenerated id and foreign key. That's not possible nor usefull
usually only classes which are abstract should containt Abstract() in the mapping
A referral has many leads. The entities are however, related by an agent identifier. Within my referral entity I ended up having to add an integer property mapped to the agent_id column in order to make the mappings work correctly.
If I remove the AgentID property from the entity and perform the mapping on the "Agent" object like so:
HasMany(x => x.Leads)
.AsBag()
.KeyColumn("Agent_Id")
.PropertyRef("Agent");
I run into an error:
Object does not match target type.
Description: An unhandled exception occurred during the execution of
the current web request. Please review the stack trace for more
information about the error and where it originated in the code.
Exception Details: System.Reflection.TargetException: Object does not
match target type.
I guess, I'm asking if this is an acceptable solution? The additional AgentID property won't be used anywhere other than within the property reference. Is there another way to perform this mapping within having to change the domain model as it cannot be changed at this time.
The working mappings:
public class Referral
{
public virtual int Id { get; set; }
public virtual int AgentID { get; set; }
public virtual Agent Agent { get; set; }
public virtual int? PositionNumber { get; set; }
public virtual DateTime? LastReferralDate { get; set; }
public virtual Account Account { get; set; }
public virtual IEnumerable<Lead> Leads { get; set; }
}
public ReferralMap()
{
Table("Referral");
LazyLoad();
Id(x => x.Id).GeneratedBy.Identity().Column("Id");
Map(x => x.PositionNumber).Column("PositionNumber");
Map(x => x.LastReferralDate).Column("LastReferralDate");
Map(x => x.AgentID).Column("Agent_ID");
References(x => x.Agent).Column("Agent_ID");
References(x => x.Account).Column("Account_id");
HasMany(x => x.Leads)
.AsBag()
.KeyColumn("Agent_Id")
.PropertyRef("AgentID");
}
i guess it is because you have
public LeadMap()
{
Id(l => l.AgentId).Column("Agent_Id");
}
instead of
public LeadMap()
{
CompositeId().KeyReference(l => l.Agent, "Agent_Id");
}
Playing around with Fluent NHibernate's Getting Started project. I tried to customize the example a bit, for a few reasons, among them elimination of circular reference for json serialization.
What I have done is to strip the Store and StoreMap classes of it's references back to Employee and Product classes. It now looks like this:
Store/StoreMap
public class Store
{
public virtual int Id { get; private set; }
public virtual string Name { get; set; }
}
public StoreMap()
{
Id(x => x.Id);
Map(x => x.Name);
}
Employee/EmployeeMap
public class Employee
{
public virtual int Id { get; private set; }
public virtual string FirstName { get; set; }
public virtual string LastName { get; set; }
public virtual Store Store { get; set; }
}
public class EmployeeMap : ClassMap<Employee>
{
public EmployeeMap()
{
Id(x => x.Id);
Map(x => x.FirstName);
Map(x => x.LastName);
References(x => x.Store).Cascade.All();
}
}
Product/ProductMap
public class Product
{
public virtual int Id { get; private set; }
public virtual string Name { get; set; }
public virtual double Price { get; set; }
public virtual IList<Store> StoresStockedIn { get; private set; }
public Product()
{
StoresStockedIn = new List<Store>();
}
public virtual void StockAt(Store store)
{
StoresStockedIn.Add(store);
}
}
public class ProductMap : ClassMap<Product>
{
public ProductMap()
{
Id(x => x.Id);
Map(x => x.Name);
Map(x => x.Price);
HasManyToMany(x => x.StoresStockedIn)
.Cascade.All()
.Table("StoreProduct");
}
}
I've moved "Cascade" operations into the Product and Employee instead of Store. From the testing I've done, both HasMany and HasManyToMany associations seem to be working okay.
My question is if it's the right approach. Whether or not it will lead to something that I have not anticipated.
as far as I know, it's standard practice in nHibernate to have both ends of a relationship in your model classes (actually, it usually makes sense from the business point of view).
Although you don't have to do it (your example, I think, should work fine).
If you don't want to expose one (or both) ends you can always define them as private or protected.
p.s concerning json serialization: it's not recommended to serialize your model entities. this is for a few reasons, the top ones being:
1. the data you display to the user may be different from what you have in your entities (for example- you might want to present an employee with their name, Id, their store name and number of products they own. it would be hard to do that using your model classes).
2. it's quite possible that you'd have uninitialized collections in your objects (if you use lazy-loading). These do not get serialized.
For serialization, DTOs is the recommended approach.