I have problem with making mapping of classes with propert of type Dictionary and value in it of type Dictionary too, like this:
public class Class1
{
public virtual int Id { get; set; }
public virtual IDictionary<DayOfWeek, IDictionary<int, decimal>> Class1Dictionary { get; set; }
}
My mapping looks like this:
Id(i => i.Id);
HasMany(m => m.Class1Dictionary);
This doesn't work. The important thing I want have everything in one table not in two. WHet I had maked class from this second IDictionary I heve bigger problem. But first I can try like it is now.
It's not currently possible to use nested collections of any type in NHibernate.
Instead, you should define your property as follows:
public virtual IDictionary<DayOfWeek, Class2> Class1Dictionary { get; set; }
And add a new class:
public class Class2
{
public virtual decimal this[int key]
{
get { return Class2Dictionary[key]; }
set { Class2Dictionary[key] = value; }
}
public virtual IDictionary<int, decimal> Class2Dictionary { get; set; }
}
This way, you can map both classes and dictionaries normally, and still access your dictionary as:
class1Instance.Class1Dictionary[DayOfWeek.Sunday][1] = 9.4
Related
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);
}
}
I am struggling with this issue:
I have a list of NHibernate objects called "Project". These objects contain a lazy - loaded list of "Branches". I am trying to pass a list of Projects to a WCF service so I am using AutoMapper to transform them to flat objects.
The problem is that even though the destination objects called "ProjectContract" does not contain a list of Branches, Automapper still invokes this collection and a lot of queries are made to the database because NHibernate fires the lazy - loading and loads the Branches collection for each project.
Here are the classes and the mapping:
public class Project
{
public virtual int ID
{
get;
set;
}
public virtual string Name { get; set; }
public virtual string Description { get; set; }
public virtual IList<Branch> Branches { get; set; }
}
[DataContract]
public class ProjectContract
{
[DataMember]
public virtual int ID
{
get;
set;
}
[DataMember]
public virtual string Name { get; set; }
[DataMember]
public virtual string Description { get; set; }
}
public class ProjectMappings : Profile
{
protected override void Configure()
{
Mapper.CreateMap<Project, ProjectContract>();
}
}
My question is: Is there a way to tell AutoMapper to not touch the "Branches" collection because I don't care about it and that is a proxy that will trigger many database calls?
I temporarily fixed this with MaxDepth(0), but there are other entities where I have collections that I want to transfer, and collections that I don't want to be touched, like this one. In that case, MaxDepth(0) will not work.
Thank you,
Cosmin
Yes, The AutoMapper Ignore function.
Mapper.CreateMap<Source, Destination>()
.ForMember(dest => dest.SomeValuefff, opt => opt.Ignore());
My class:
[PersistClass]
public class ExternalAccount
{
public virtual AccountType AccountType { get; set; }
public virtual int Id { get; private set; }
public virtual User User { get; set; }
public virtual Dictionary<string, string> Parameters { get; set; }
public ExternalAccount()
{
Parameters = new Dictionary<string, string>();
}
}
The Dictionary is not getting mapped. I understand that automapping doesn't work by default with Dictionaries, how do I configure the mapping? All Parameters is is a list of key/value pairs - so I would expect them to be stored in a table with a foreign key to the externalaccount table. I know I can do this with another class - but it makes access to the parameters in the class more difficult - I'd rather have to configure the complexity once.
Please bear in mind I am new Fluent and to nHibernate.
Thanks
Using a simple class relationship such as the following:
public class Foo {
public virtual IDictionary<string, Bar> Bars { get; set; }
}
public class Bar {
public virtual string Type { get; set; }
public virtual int Value { get; set; }
}
You can map this with Fluent NHibernate in this way:
mapping.HasMany(x => x.Bars)
.AsMap(x => x.Type);
Where Bar.Type is used as the index field into the dictionary.
FluentNHibernate mapping for Dictionary
Suppose I have a table:
ID(pk) | HOME_EMAIL | WORK_EMAIL | OTHER_EMAIL
-------------------------------------------------
and the .NET classes
class A {
int id;
List<MyEmail> emails;
}
class MyEmail {
string email;
}
I suppose there's no way to map those (multiple) columns into a single collection in NHibernate, or is there? :)
It's come to a point that we'd rather not tinker with the database schema anymore so we can't do much with the database, if that helps.
I would suggest working with Interfaces so you could do something like this
interface IUser
{
int Id {get; set;}
IEnumerable<string> Emails {get;}
}
class MyUser : IUser
{
public int Id {get; set;}
public IEnumerable<string> Emails
{
get
{
return new [] { SomeEmail, SomeOtherEmail };
}
}
public string SomeEmail { get; set; }
public string SomeOtherEmail { get; set; }
}
Your application can expect an IUser and not care where we got the list of emails. You would map MyUser in NH, while the application does not (and should not) care about the actual implementation.
If it doesn't have to be a collection, but could be a custom type instead, say EmailAddresses which contains three properties:
public class EmailAddresses
{
public virtual string Home { get; set; }
public virtual string Work { get; set; }
public virtual string Other { get; set; }
}
You could use a component to map the three columns into the three properties of this object as a single property on the parent:
public class MyUser
{
...
public virtual EmailAddresses { get; set; }
}
You can map these in NHibernate using components or if you're using Fluent NHibernate with the ComponentMap<T> classmap (automapper can't do components).
There is a feature that's very close to what you want, <dynamic-component>
The documentation at http://nhibernate.info/doc/nh/en/index.html#components-dynamic should get you started.
I have a requirement to load a complex object called Node...well its not that complex...it looks like follows:-
A Node has a reference to EntityType which has a one to many with Property which in turn has a one to many with PorpertyListValue
public class Node
{
public virtual int Id
{
get;
set;
}
public virtual string Name
{
get;
set;
}
public virtual EntityType Etype
{
get;
set;
}
}
public class EntityType
{
public virtual int Id
{
get;
set;
}
public virtual string Name
{
get;
set;
}
public virtual IList<Property> Properties
{
get;
protected set;
}
public EntityType()
{
Properties = new List<Property>();
}
}
public class Property
{
public virtual int Id
{
get;
set;
}
public virtual string Name
{
get;
set;
}
public virtual EntityType EntityType
{
get;
set;
}
public virtual IList<PropertyListValue> ListValues
{
get;
protected set;
}
public virtual string DefaultValue
{
get;
set;
}
public Property()
{
ListValues = new List<PropertyListValue>();
}
}
public class PropertyListValue
{
public virtual int Id
{
get;
set;
}
public virtual Property Property
{
get;
set;
}
public virtual string Value
{
get;
set;
}
protected PropertyListValue()
{
}
}
What I a trying to do is load the Node object with all the child objects all at once. No Lazy load. The reason is I have thousands of Node objects in the database and I have to send them over the wire using WCF Service.I ran into the classes SQL N+ 1 problem. I am using Fluent Nhibernate with Automapping and NHibernate Profiler suggested me to use FetchMode.Eager to load the whole objects at once. I am using the following qyuery
Session.CreateCriteria(typeof (Node))
.SetFetchMode( "Etype", FetchMode.Join )
.SetFetchMode( "Etype.Properties", FetchMode.Join )
.SetFetchMode( "Etype.Properties.ListValues", FetchMode.Join )
OR using NHibernate LINQ
Session.Linq<NodeType>()
.Expand( "Etype")
.Expand( "Etype.Properties" )
.Expand( "Etype.Properties.ListValues" )
When I run any of the above query, they both generate one same single query with all the left outer joins, which is what I need. However, for some reason the return IList from the query is not being loaded property into the objects. Infact the returned Nodes count is equal to the number of rows of the query, so the Nodes objects are repeated.Moreover, the properties within each Node are repeated, and so do the Listvalues.
So I would like to know how to modify the above query to return all unique Nodes with the properties and list values within them.
each mapping has to have lazy loading off
in Node Map:
Map(x => x.EntityType).Not.LazyLoad();
in EnityType Map:
Map(x => x.Properties).Not.LazyLoad();
and so on...
Also, see NHibernate Eager loading multi-level child objects for one time eager loading
Added:
Additional info on Sql N+1:
http://nhprof.com/Learn/Alerts/SelectNPlusOne
I figure it out myself. The key is to use SetResultTransformer() passing an object of DistinctRootEntityResultTransformer as a parameter. So the query now looks like as follows
Session.CreateCriteria(typeof (Node))
.SetFetchMode( "Etype", FetchMode.Join )
.SetFetchMode( "Etype.Properties", FetchMode.Join )
.SetFetchMode( "Etype.Properties.ListValues", FetchMode.Join )
.SetResultTransformer(new DistinctRootEntityResultTransformer());
I found the answer to my questions through these links:
http://www.mailinglistarchive.com/html/nhusers#googlegroups.com/2010-05/msg00512.html
http://ayende.com/Blog/archive/2010/01/16/eagerly-loading-entity-associations-efficiently-with-nhibernate.aspx
I ended up with something like this:
HasMany(x => x.YourList).KeyColumn("ColumnName").Inverse().Not.LazyLoad().Fetch.Join()
Just make sure to select your entity like this, to avoid duplication due to the join:
session.CreateCriteria(typeof(T)).SetResultTransformer(Transformers.DistinctRootEntity).List<T>();
SetResultTransformer with DistinctRootEntityResultTransformer will only work for Main object but IList collections will be multiplied.