I have standard one-to-many table setup, but I want to be able to map it to a class structure that looks like this:
Class 1 -> Mapped to Table 1 (The one- side of the one-to-many relationship)
|
--- Intermediary class that has additional methods on and has a List of Class 2
|
---- Class 2 -> Mapped to Table 2 (The -many side of the relationship)
Is this possible with NHibernate?
it is possible for example
class Class1Map : ClassMap<Class1>
{
public Class1Map()
{
Id(x => x.Id);
Component(c =>
{
c.Map(x => x.Foo);
c.HasMany(x => x.Classes2);
});
}
}
Related
I'm trying to map two entities and the other similar questions could not help me.
class Dog {
int id;
string Name;
}
class Person {
int id;
string Name;
Dog Dog;
}
A person must have only one dog, but a dog could be a pooch.
In the database, there is a FK from table Dog with the nullable column idPerson pointing to the table Person.
I'm currently mapping with these statement:
modelBuilder.Entity<Person>().HasOptional(x => x.Dog).WithOptionalPrincipal().Map(x => x.MapKey("idPerson"));
because I can not do this:
modelBuilder.Entity<Person>().HasRequired(x => x.Dog).WithOptional().Map(x => x.MapKey("idPerson"));
or this:
modelBuilder.Entity<Person>().HasRequired(x => x.Dog).WithMany().Map(x => x.MapKey("idPerson"));
or wathever.
I am new here, so sorry for any mistake.
Could anyone help me?
So, I'm having a problem mapping in fluent nhibernate. I want to use a join mapping to flatten an intermediate table: Here's my structure:
[Vehicle]
VehicleId
...
[DTVehicleValueRange]
VehicleId
DTVehicleValueRangeId
AverageValue
...
[DTValueRange]
DTVehicleValueRangeId
RangeMin
RangeMax
RangeValue
Note that DTValueRange does not have a VehicleID. I want to flatten DTVehicleValueRange into my Vehicle class. Tgis works fine for AverageValue, since it's just a plain value, but I can't seem to get a ValueRange collection to map correctly.
public VehicleMap()
{
Id(x => x.Id, "VehicleId");
Join("DTVehicleValueRange", x =>
{
x.Optional();
x.KeyColumn("VehicleId");
x.Map(y => y.AverageValue).ReadOnly();
x.HasMany(y => y.ValueRanges).KeyColumn("DTVehicleValueRangeId"); // This Guy
});
}
The HasMany mapping doesn't seem to do anything if it's inside the Join. If it's outside the Join and I specify the table, it maps, but nhibernate tries to use the VehicleID, not the DTVehicleValueRangeId.
What am I doing wrong?
Can you explain the average value column in the DTVehicleValueRange table? Isn't this a calculated value (i.e. no need to persist it)?
It looks like you have a many-to-many relationship between Vehicle and DTValueRange, which of course would not be mapped with a join, rather with a HasManyToMany call.
Ran into a similar issue today using a Map to create a view. The SQL generated showed it trying to do the HasMany<> inside the join based on the Id of the ParentThing and not WorkThing (same problem you were having)
After much mapping of head-to-desk it turns out adding the propertyref onto the hasmany solved it.
public class ThingMap : ClassMap<WorkThingView> {
public ThingMap() {
ReadOnly();
Table("ParentThing");
Id(x => x.ParentThingId);
Map(x => x.ParentName);
Join("WorkThing", join => {
join.KeyColumn("ParentThingId");
join.Map(m => m.FooCode);
join.Map(m => m.BarCode);
join.Map(x => x.WorkThingId);
join.HasMany(x => x.WorkThingCodes)
.Table("WorkThingCode").KeyColumn("WorkThingId").PropertyRef("WorkThingId")
.Element("WorkThingCode");
});
}
}
I have a legacy system where the relationship between 2 tables haven't been defined explictly and there aren't any keys (primary or unqiue defined). The only related columns is 'Username'
Something like:
Table: Customer
Column: Id,
Column: Username,
Column: FirstName,
Table: Customer_NEW
Column: Username
Column: FirstNameNew
I have following Mapping definitions:
public sealed class CustomerMap : ClassMap<Customer>, IMap
{
public CustomerMap()
{
WithTable("customers");
Not.LazyLoad();
Id(x => x.Id).GeneratedBy.Increment();
References(x => x.CustomerNew, "Username")
.WithForeignKey("Username")
.Cascade.All();
}
public sealed class CustomerNewMap : ClassMap<CustomerNew>, IMap
{
public CustomerNewMap()
{
WithTable("customers_NEW");
Not.LazyLoad();
Id(x => x.Username).GeneratedBy.Assigned();
Map(x => x.FirstNameNew);
}
}
The problem is nHibernate is generating an UPDATE statement for the 'Reference' in the Customer Mapping definition which is obviously failing when attempting to insert a new Customer object which has a reference to CustomerNew object.
How do I get the mapping definition to generate the INSERT statement instead of an UPDATE for the 'Save' command?
Cheers in advance
Ollie
The reason is because there isn't any referential integrity in the database, no primary keys, composite keys not foreign key constraints…
Yet again another application that has a database that’s not fit for purpose…
I have this fluent mapping:
sealed class WorkPostClassMap : ClassMap<WorkPost>
{
public WorkPostClassMap()
{
Not.LazyLoad();
Id(post => post.Id).GeneratedBy.Identity().UnsavedValue(0);
Map(post => post.WorkDone);
References(post => post.Item).Column("workItemId").Not.Nullable();
References(Reveal.Property<WorkPost, WorkPostSheet>("Owner"), "sheetId").Not.Nullable();
}
parent class:
sealed class WorkPostSheetClassMap : ClassMap<WorkPostSheet>
{
public WorkPostSheetClassMap()
{
Id(sheet => sheet.Id).GeneratedBy.Identity().UnsavedValue(0);
Component(sheet => sheet.Period, period =>
{
period.Map(p => p.From, "PeriodFrom");
period.Map(p => p.To, "PeriodTo");
});
References(sheet => sheet.Owner, "userId").Not.Nullable();
HasMany(sheet => sheet.WorkPosts).KeyColumn("sheetId").AsList();
}
WorkItem class:
sealed class WorkItemClassMap : ClassMap<WorkItem>
{
public WorkItemClassMap()
{
Not.LazyLoad();
Id(wi => wi.Id).GeneratedBy.Assigned();
Map(wi => wi.Description).Length(500);
Version(wi => wi.LastChanged).UnsavedValue(new DateTime().ToString());
}
}
And when a collection of WorkPosts are lazy loaded from the owning work post sheet I get the following select statement:
SELECT workposts0_.sheetId as sheetId2_,
workposts0_.Id as Id2_,
workposts0_.idx as idx2_,
workposts0_.Id as Id2_1_,
workposts0_.WorkDone as WorkDone2_1_,
workposts0_.workItemId as workItemId2_1_,
workposts0_.sheetId as sheetId2_1_,
workitem1_.Id as Id1_0_,
workitem1_.LastChanged as LastChan2_1_0_,
workitem1_.Description as Descript3_1_0_
FROM "WorkPost" workposts0_
inner join "WorkItem" workitem1_ on workposts0_.workItemId=workitem1_.Id
WHERE workposts0_.sheetId=#p0;#p0 = 1
No, there are a couple of things here which doesn't make sence to me:
The workpost "Id" property occurs twice in the select statement
There is a select refering to a column named "idx" but that column is not a part of any fluent mapping.
Anyone who can help shed some light on this?
The idx column is in the select list because you have mapped Sheet.WorkPosts as an ordered list. The idx column is required to set the item order in the list. I'm not sure why the id property is in the select statement twice.
By the way, an unsaved value of 0 is the default for identity fields, so you can remove .UnsavedValue(0) if you want.
Entities:
Team <-> TeamEmployee <-> Employee
Requirements:
A Team and an Employee can exist without its counterpart.
In the Team-TeamEmployee relation the Team is responsible (parent) [using later a TeamRepository].
In the Employee-TeamEmployee relation the Employee is responsible (parent) [using later an EmployeeRepository].
Duplicates are not allowed.
Deleting a Team deletes all Employees in the Team, if the Employee is not in another Team.
Deleting an Employee deletes only a Team, if the Team does not contain no more Employees.
Mapping:
public class TeamMap : ClassMap<Team>
{
public TeamMap()
{
// identity mapping
Id(p => p.Id)
.Column("TeamID")
.GeneratedBy.Identity();
// column mapping
Map(p => p.Name);
// associations
HasMany(p => p.TeamEmployees)
.KeyColumn("TeamID")
.Inverse()
.Cascade.SaveUpdate()
.AsSet()
.LazyLoad();
}
}
public class EmployeeMap : ClassMap<Employee>
{
public EmployeeMap()
{
// identifier mapping
Id(p => p.Id)
.Column("EmployeeID")
.GeneratedBy.Identity();
// column mapping
Map(p => p.EMail);
Map(p => p.LastName);
Map(p => p.FirstName);
// associations
HasMany(p => p.TeamEmployees)
.Inverse()
.Cascade.SaveUpdate()
.KeyColumn("EmployeeID")
.AsSet()
.LazyLoad();
HasMany(p => p.LoanedItems)
.Cascade.SaveUpdate()
.LazyLoad()
.KeyColumn("EmployeeID");
}
}
public class TeamEmployeeMap : ClassMap<TeamEmployee>
{
public TeamEmployeeMap()
{
Id(p => p.Id);
References(p => p.Employee)
.Column("EmployeeID")
.LazyLoad();
References(p => p.Team)
.Column("TeamID")
.LazyLoad();
}
}
Creating Employees and Teams:
var employee1 = new Employee { EMail = "Mail", FirstName = "Firstname", LastName = "Lastname" };
var team1 = new Team { Name = "Team1" };
var team2 = new Team { Name = "Team2" };
employee1.AddTeam(team1);
employee1.AddTeam(team2);
var employee2 = new Employee { EMail = "Mail2", FirstName = "Firstname2", LastName = "Lastname2" };
var team3 = new Team { Name = "Team3" };
employee2.AddTeam(team3);
employee2.AddTeam(team1);
team1.AddEmployee(employee1);
team1.AddEmployee(employee2);
team2.AddEmployee(employee1);
team3.AddEmployee(employee2);
session.SaveOrUpdate(team1);
session.SaveOrUpdate(team2);
session.SaveOrUpdate(team3);
session.SaveOrUpdate(employee1);
session.SaveOrUpdate(employee2);
After this I commit the changes by using transaction.Commit().
The first strange thing is that I have to save Teams and Employees instead only one of them (why?!). If I only save all teams or (Xor) all employees then I get a TransientObjectException:
"object references an unsaved
transient instance - save the
transient instance before flushing.
Type: Core.Domain.Model.Employee,
Entity: Core.Domain.Model.Employee"
When I save all created Teams and Employees everything saves fine, BUT the relation table TeamEmployee has duplicate assoications.
ID EID TID
1 1 1
2 2 1
3 1 2
4 2 3
5 1 1
6 1 2
7 2 3
8 2 1
So instead of 4 relations there are 8 relations. 4 relations for the left side and 4 relations for the right side. :[
What do I wrong?
Further questions: When I delete a Team or an Employee, do I have to remove the team or the Employee from the TeamEmployee list in the object model or does NHibernate make the job for me (using session.delete(..))?
You are talking about business logic. It's not the purpose of NHibernate to implement the business logic.
What your code is doing:
You mapped two different collections of TeamEmployees, one in Team, one in Employee. In your code, you add items to both collections, creating new instances of TeamEmployee each time. So why do you expect that NHibernate should not store all these distinct instances?
What you could do to fix it:
You made TeamEmployee an entity (in contrast to a value type). To create an instance only once, you would have to instantiate it only once in memory and reuse it in both collections. Only do this when you really need this class in your domain model. (eg. because it contains additional information about the relations and is actually an entity of its own.)
If you don't need the class, it is much easier to map it as a many-to-many relation (as already proposed by Chris Conway). Because there are two collections in memory which are expected to contain the same data, you tell NHibernate to ignore one of them when storing, using Inverse.
The parent on both ends problem
There is no parent on both ends. I think it's clear that neither the Team nor the Employee is a parent of the other, they are independent. You probably mean that they are both parents of the intermediate TeamEmployee. They can't be parent (and therefore owner) of the same instance. Either one of them is the parent, or it is another independent instance, which makes managing it much more complicated (this is how you implemented it now). If you map it as a many-to-many relation, it will be managed by NHibernate.
To be done by your business logic:
storing new Teams and new Employees
managing the relations and keeping them in sync
deleting Teams and Employees when they are not used anymore. (There is explicitly no persistent garbage collection implementation in NHibernate, for several reasons.)
Looks like you need a HasManyToMany instead of two HasMany maps. Also, there is no need for the TeamEmployeeMap unless you have some other property in that table that needs mapped. Another thing, only one side needs to have the Inverse() set and since you're adding teams to employees I think you need to make the TeamMap the inverse. Having the inverse on one side only will get rid of the duplicate entries in the database.
Maybe something like this:
public class TeamMap : ClassMap<Team>
{
public TeamMap()
{
// identity mapping
Id(p => p.Id)
.Column("TeamID")
.GeneratedBy.Identity();
// column mapping
Map(p => p.Name);
// associations
HasManyToMany(x => x.TeamEmployees)
.Table("TeamEmployees")
.ParentKeyColumn("TeamID")
.ChildKeyColumn("EmployeeID")
.LazyLoad()
.Inverse()
.AsSet();
}
}
public class EmployeeMap : ClassMap<Employee>
{
public EmployeeMap()
{
// identifier mapping
Id(p => p.Id)
.Column("EmployeeID")
.GeneratedBy.Identity();
// column mapping
Map(p => p.EMail);
Map(p => p.LastName);
Map(p => p.FirstName);
// associations
HasManyToMany(x => x.TeamEmployees)
.Table("TeamEmployees")
.ParentKeyColumn("EmployeeID")
.ChildKeyColumn("TeamID")
.Cascade.SaveUpdate()
.LazyLoad()
.AsSet();
HasMany(p => p.LoanedItems)
.Cascade.SaveUpdate()
.LazyLoad()
.KeyColumn("EmployeeID");
}
}
Using this, the delete will delete the TeamEmployee from the database for you.
NHibernate does not allow many-to-many association with parents at both ends.