I have read that this mapping is not possible in NHibernate 3.3:
<class name="Digital" table="DIGITALS">
<composite-id>
<key-many-to-one name="Person" class="Person" column="PERSONID" />
<key-property name="Id" column="ID">
**<generator class="increment"/>**
<key-property/>
</composite-id>
<property name="Nombre" column="NOMBRE" />
Basically I need a composite-id's property to be calculated automatically by NH.
Maybe exists a technique to get something similar?
Thanks in advance.
you have to implement it yourself since CompositeIds are always generatedby assigned for NH
class Digital
{
private static long number = 0;
private static long NextNumber()
{
return Interlocked.Increment(ref number);
}
public Digital()
{
Id = NextNumber();
}
}
Related
I need to retrieve all the users with a valid Wish property (so not null). This is the xml of my class:
<class name="Project.Engine.Domain.User,Project.Engine" table="Users" lazy="true">
<id name="UserID" column="UserID">
<generator class="native" />
</id>
<property name="Firstname" column="Firstname" type="string" not-null="true"
length="255" />
<property name="Lastname" column="Lastname" type="string" not-null="true"
length="255" />
<property name="Email" column="Email" type="string" not-null="true"
length="255" />
<one-to-one name="Wish" cascade="all" property-ref="UserID"
class="Project.Engine.Domain.Wish, Project.Engine" />
</class>
The method to get all my users is the following:
public PagedList<User> GetAll(int pageIndex, int pageSize,
string orderBy, string orderByAscOrDesc)
{
using (ISession session = NHibernateHelper.OpenSession())
{
var users = session.CreateCriteria(typeof(User));
users.Add(Restrictions.IsNotNull("Wish"));
return users.PagedList<User>(session, pageIndex, pageSize);
}
}
As you can notice, I have added the Restriction on the child object. This doesn't work properly as the method return all users including the ones with Wish property as null. Any help?
this is the xml for child:
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="Project.Engine.Domain.Wish,Project.Engine" table="Wish" lazy="false">
<id name="WishID" column="WishID">
<generator class="native" />
</id>
<property name="UserID" column="UserID" type="int" not-null="true" length="32" />
<property name="ContentText" column="ContentText" type="string" not-null="false" length="500" />
<property name="Views" column="Views" type="int" not-null="true" length="32" />
<property name="DateEntry" column="DateEntry" type="datetime" not-null="true" />
</class>
</hibernate-mapping>
Well, there is a bug with one-to-one and null testing of the side which may not exist. I had already encountered it but forgot about it. The property-ref just render it a bit more tricky to diagnose, but it does exist on actual one-to-one too.
Here is its corresponding issue in NHibernate tracking tool.
Workaround: test for null state of an non-nullable property of Wish, like Wish.Views.
Forgive the wild guess on test syntax, I do not use nhibernate-criteria anymore since years, but try by example:
public PagedList<User> GetAll(int pageIndex, int pageSize,
string orderBy, string orderByAscOrDesc)
{
using (ISession session = NHibernateHelper.OpenSession())
{
var users = session.CreateCriteria(typeof(User));
users.Add(Restrictions.IsNotNull("Wish.Views"));
return users.PagedList<User>(session, pageIndex, pageSize);
}
}
Using linq-to-nhibernate, I confirm this workaround works with my own projects, which gives by example:
// The "TotalAmount != null" seems to never be able to come false from a
// .Net run-time view, but converted to SQL, yes it can, if TransactionRecord
// does not exist.
// Beware, we may try "o.TransactionsRecord != null", but you would get struck
// by https://nhibernate.jira.com/browse/NH-3117 bug.
return q.Where(o => o.TransactionsRecord.TotalAmount != null);
I maintain my other answer since you may consider using a many-to-one instead, especially since you do not have made a bidirectionnal mapping (no corresponding constrained one-to-one in Wish) in addition to not having an actual one-to-one. many-to-one does not suffer of the bug.
one-to-one mapping using property-ref is not an "actual" one-to-one, and usually this is a sign a many-to-one mapping should be used instead.
Maybe this is not related to your trouble, but you may give it a try.
An "actual" one-to-one has the dependent table primary key equals to the parent table primary key. (Dependent table, Wish in your case, would have a foreign primary key, UserId in your case. See this example.)
I have sometime "played" with 'one-to-one property-ref', and I always ended giving it up due to many issues. I replaced that with more classical mappings, either changing my db for having an actual one-to-one, or using a many-to-one and living with a collection on child side though it would always contain a single element.
Why can't NHibernate access a property inherited from an abstract base class. When I try to use the property in a QueryOver in the Where clause I'm getting
could not resolve property: ID of: TheWorkshop.Web.Models.Customer
var customer = Session.QueryOver<Customer>()
.Where(c=>c.ID ==id)
.SingleOrDefault<Customer>();
Intelisense helped me build the query and the solution compiles, so there is an ID property on the Customer class. The ID property on Customer is inherited from an abstract Contact class that in turn inherits from a DomainEntity<T> which exposes a protected field.
public abstract class DomainEntity<T>
{
protected Guid _persistenceId;
//...
}
public abstract class Contact : DomainEntity<Contact>
{
public virtual Guid ID
{
get { return _persistenceId; }
}
public virtual Address Address
{
get { return _address; }
set { _address = value; }
}
//...
}
and in the mapping file
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="TheWorkshop.Web"
namespace="TheWorkshop.Web.Models"
default-access="field.camelcase-underscore"
default-lazy="true">
<class name="Contact" table="Contacts" abstract="true">
<id name="_persistenceId" column="ID" type="Guid" access="field"
unsaved-value="00000000-0000-0000-0000-000000000000">
<generator class="guid.comb" />
</id>
<!-- ... -->
<union-subclass name="Customer" table="Customers">
Following the answer to a similar question I updated to NHibernate 3.3.3-CR1 from NHibernate 3.3.2.4000 but I still have the same issue.
The problem was that NHibernate couldn't infer from my mapping how to resolve the ID property. So although the classes compiled fine and the _persistenceId property on the abstract base class could be accessed through a getter on the implementing classes, because of the mismatch in names between _persistenceId and ID NHibernate wasn't able to follow that.
The (easier) solution was to change my names to match up. There is a harder solution which involves implementing the IProperyAccessor, IGetter and ISetter interfaces and in order to provide a path to pass the string ID in order to use the ClassName access strategy.
The simpler of the two solutions was just to rename _persistenceId to _id (and update all the references to it) so
<id name="_persistenceId" column="ID" type="Guid" access="field"
unsaved-value="00000000-0000-0000-0000-000000000000">
becomes
<id name="Id" column="Id" type="Guid"
unsaved-value="00000000-0000-0000-0000-000000000000">
Note I was also able to drop the access="field" in the updated id mappings
I am working with a brownfield database and am trying to configure a subclass map which joins to its subclasses with a column other than that of the specified id. The login table has a primary key column login_sk which I'd like to use as its id. It joins to two tables via a login_cust_id column (to make things more fun the corresponding columns in the adjoining tables are named differently). If I setup login_cust_id as the id of the UserMap it joins to its subclasses as expected. For what I hope are obvious reasons I do not want to use login_cust_id as the id for my User objects.
public class UserMap : ClassMap<IUser>
{
public UserMap()
{
Table("login");
Id(x => x.Id).Column("login_sk"); // want to setup map like this
// if used instead this works for subclass joining / mapping
// Id(x => x.Id).Column("login_cust_id");
// would prefer to only reference login_cust_id for subclass mapping
}
}
public class CustomerUserMap : SubclassMap<CustomerUser>
{
public CustomerUserMap()
{
Table("customer");
Map(c => c.DisplayName, "cust_mail_name");
Map(c => c.RecordChangeName, "cust_lookup_name");
KeyColumn("cust_id");
}
}
public class EntityUserMap : SubclassMap<EntityUser>
{
public EntityUserMap()
{
Table("entity");
Map(c => c.DisplayName, "entity_name");
KeyColumn("entity_id");
}
}
What I'd like to do is only use the login_cust_id column when joining to subclasses. Is there a fluent mapping setting that allows me to specify this? If not a fluent mapping is there a regular NHibernate XML mapping that would work? I'd prefer to not even map the column and only use it for joining if possible. If it helps there is a potential discriminator column login_holder_type which indicates which table to join to.
It did occur to me to setup an IClassConvention but after poking at the passed IClassInstance I could not determine any settings which would help me.
public class UserIdConvention : IClassConvention, IClassConventionAcceptance
{
public void Apply(IClassInstance instance)
{
// do something awesome with instance.Subclasses to
// specify the use of login_cust_id for subclass joining...
}
public void Accept(IAcceptanceCriteria<IClassInspector> criteria)
{
criteria.Expect(x => typeof(User).Equals(x.EntityType));
}
}
The lack of a populated Subclasses collection for the passed instance caused me to look for a more specific inspector which IParentInspector appears to be. Unfortunately Fluent NHibernate does not appear to have corresponding implementations for IParentInstance, IParentConvention or IParentConventionAcceptance like it does for IJoinedSubclassInspector. While I could probably implement my own before I do I wanted to ensure I wasn't barking up the wrong tree.
Is this sort of subclass id adjustment even possible? Am I missing something obvious in either my map or the Fluent NHibernate Conventions namespace? How can I map to a joined subclass with a different column/property than the id of parent?
I was able to think of three possible solution to your problem please see my findings below.
Solution 1: Discriminator based mapping with Join
My initial idea was to use a discriminator based mapping for modelling the inheritance, with each sub-class containing a join with a property ref, i.e
<class name="IUser" abstract="true" table="login">
<id name="Id" column="login_sk">
<generator class="identity"/>
</id>
<discriminator column="login_holder_type" not-null="true" type="System.String"/>
<subclass name="CustomerUser" discriminator-value="Customer">
<join table="customer" >
<key column="cust_id" property-ref="login_cust_id" />
<property name="DisplayName" column="cust_mail_name"/>
<property name="RecordChangeName" column="cust_lookup_name" />
</join>
</subclass>
<subclass name="EntityUser" discriminator-value="Entity">
<join table="entity" >
<key column="entity_id" property-ref="login_cust_id" />
<property name="CompanyName"/>
</join>
</subclass>
</class>
Unfortunately at this time this feature is supported in Hibernate but not in NHibernate. Please see here and here for the outstanding tickets. Some work has gone towards adding this feature which can be seen on this fork on github.
Solution 2: Discriminator based mapping with Many-to-One
Another option is to still use the discriminator based mapping, but use a many-to-one mapping within each of the sub-classes, which would allow you to join on the foreign key using a property-ref. This has the disadvantage of requiring separate classes for all of the properties in your customer and entity tables but is a workable solution.
<class name="IUser" abstract="true" table="login">
<id name="Id" column="login_sk">
<generator class="identity"/>
</id>
<discriminator column="login_holder_type" not-null="true" type="System.String"/>
<subclass name="CustomerUser" discriminator-value="Customer">
<many-to-one name="CustomerProps" property-ref="login_cust_id" />
</subclass>
<subclass name="EntityUser" discriminator-value="entity">
<many-to-one name="EntityProps" property-ref="login_cust_id" />
</subclass>
</class>
<class name="CustomerProps" Table="customer" >
<id name="Id" column="cust_id">
<generator class="assigned"/>
</id>
<property name="DisplayName" column="cust_mail_name"/>
<property name="RecordChangeName" column="cust_lookup_name" />
</class>
<class name="EntityProps" Table="entity" >
<id name="Id" column="entity_id">
<generator class="assigned"/>
</id>
<property name="CompanyName"/>
</class>
Solution 3: Discriminator based mapping with Joins to Updatable Views
The final option is to create an Updatable View in the DB for the customer and entity tables which contains the login_sk field. You can then use Join within each sub-class as you wouldn't require the property-ref.
<class name="IUser" abstract="true" table="login">
<id name="Id" column="login_sk">
<generator class="identity"/>
</id>
<discriminator column="login_holder_type" not-null="true" type="System.String"/>
<subclass name="CustomerUser" discriminator-value="Customer">
<join table="customerView" >
<key column="login_sk" />
<property name="DisplayName" column="cust_mail_name"/>
<property name="RecordChangeName" column="cust_lookup_name" />
</join>
</subclass>
<subclass name="EntityUser" discriminator-value="Entity">
<join table="entityView" >
<key column="login_sk" />
<property name="CompanyName"/>
</join>
</subclass>
</class>
I am trying to create a table-per-hierarchy mapping using NHibernate 2.0.1.
I have a base class with properties that exist for each subclass that other classes inherit from. All of these objects are persisted to one table called Messages that contain all of the possible fields for each class. There is a SourceID which is the discriminator and should indicate which Poco to return for each subclass. Here is my current mapping.
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="NS.Core"
namespace="NS.Core.Model">
<class name="BaseMessage" table="Messages">
<id name="MessageID" type="Int64">
<column name="MessageID" />
<generator class="native" />
</id>
<discriminator column="SourceID" type="Int32"/>
<property name="DateCreated" access="property" column="DateCreated" type="DateTime" not-null="true"/>
<property name="DatePublished" access="property" column="DatePublished" type="DateTime"/>
<property name="SourceID" access="property" column="SourceID" type="Int32"/>
<many-to-one name="User" column="UserID" access="property" cascade="none" lazy="false" fetch="join" outer-join="true" />
<subclass name="NMessage" discriminator-value="0">
<property name="Body" access="property" column="Body" type="String"/>
</subclass>
<subclass name="BMessage" discriminator-value="1">
<property name="Title" access="property" column="Title" type="String"/>
<property name="Body" access="property" column="Body" type="String"/>
</subclass>
<subclass name="CMessage" discriminator-value="2">
<property name="Url" access="property" column="Url" type="String"/>
<property name="Body" access="property" column="Body" type="String"/>
</subclass>
</class>
</hibernate-mapping>
I get an error querying saying Could not format discriminator value to SQL string of entity NS.Core.Model.BaseMessage so I put a discriminator value on this class too althout it should never return the base class. That led me to some antlr errors.
Am I taking the wrong approach to this problem? I would like to query the table and get back a list of different POCOs that all inherit from the base class. It would never return the base class itself.
below is the BaseMessage.cs
using System;
using System.Collections.Generic;
using System.Runtime.Serialization;
using System.Text;
namespace NS.Core.Model
{
[Serializable]
[DataContract]
[KnownType(typeof(User))]
public class BaseMessage
{
#region Private variables
private long _messageID;
private DateTime? _dateCreated;
private DateTime? _datePublished;
private int _sourceID;
private User _user = new User();
#endregion
#region Properties
[DataMember]
public virtual long MessageID
{
get { return _messageID; }
set { this._messageID = value; }
}
[DataMember]
public virtual DateTime? DateCreated
{
get { return _dateCreated; }
set { this._dateCreated = value; }
}
[DataMember]
public virtual DateTime? DatePublished
{
get { return _datePublished; }
set { this._datePublished = value; }
}
[DataMember]
public virtual int SourceID
{
get { return _sourceID; }
set { this._sourceID = value; }
}
[DataMember]
public virtual User User
{
get
{
if (this._user != null)
{ return this._user; }
else { return new User(); }
}
set { this._user = value; }
}
#endregion
}
}
The approach is sound. I have done exactly this several times.
You could make it explicit in your code my having BaseMessage's default constructor be protected.
You need to declare a discriminator-value on the base class as well.
I favor string values for discriminators, as this clearer when performing SQL queries or reports. Also, since instances of BaseMessage shoudl not exist, in would use null for its discriminator value.
<class name="BaseMessage" table="Messages" discriminator-value="null">
<id />
<discriminator column="SourceID" />
<subclass name="NMessage" discriminator-value="NMessage">
</subclass>
<subclass name="BMessage" discriminator-value="BMessage">
</subclass>
<subclass name="CMessage" discriminator-value="CMessage">
</subclass>
</class>
Also, I see that you have mapped a property to the discriminator column. You should instead have a method that returns something unique to the class - in this case the code.
Note that you cannot change the class of a mapped entity after it has been saved. Not even by changing the discriminator. If you did change it via SQL, your 2nd level cache will still hold a version with the original class.
class BaseMessage
{
public virtual string MessageType { return null; }
}
class NMessage : BaseMessage
{
public override string MessageType { return "NMessage"; }
}
Finally, your mapping file is overly verbose as it includes values which are the default. The following attributes and elements can be removed:
access="property" - this is the default
type="String" - all the types you use can be inferred from your .NET class
column="COL" - default is the same as the name
similarly for the id column element
All of your Message subclasses have property Body, so move it to the base class mapping. If this field can be longer than your database varchar, it should be a text column and have type="StringCLob" which maps to string in .NET
<class name="BaseMessage" table="Messages" discriminator-value="null">
<id name="MessageID">
<generator class="native" />
</id>
<discriminator column="SourceID"/>
<property name="DateCreated" />
<property name="DatePublished" />
<many-to-one name="User" column="UserID" cascade="none" lazy="false" fetch="join" outer-join="true" />
<property name="Body" type="StringCLob" />
<subclass name="NMessage" discriminator-value="NMessage">
</subclass>
<subclass name="BMessage" discriminator-value="BMessage">
<property name="Title" />
</subclass>
<subclass name="CMessage" discriminator-value="CMessage">
<property name="Url" />
</subclass>
</class>
I have a class StoreHours that has a composite key and has been working perfectly. A new demand came up for another type of hours to be returned. I thought "simple, I'll abstract the base class, have two concrete implementations and change my references in the app to one of the new classes". However, upon doing that, my unit tests failed with
X.Test.StoreTest.HoursTest: NHibernate.InstantiationException : Cannot instantiate abstract class or interface: X.Model.StoreHours
My mapping file looks like
<class name="StoreHours" table="StoreHour" abstract="true" discriminator-value="0" >
<composite-id>
<key-many-to-one name="Store"
class="Store"
column="StoreUid"/>
<key-property name="DayOfWeek"
column="DayOfWeekId"
type="System.DayOfWeek" />
</composite-id>
<discriminator column="StoreHourType" type="Byte" />
<property name="OpenMinutes" column="OpenTime" />
<property name="CloseMinutes" column="CloseTime" />
<subclass name="OfficeHours" discriminator-value="1" />
<subclass name="AccessHours" discriminator-value="2" />
</class>
I found someone with similar troubles here and started down their solution path but actually ended up with even more troubles than I started with.
I can persist the records to the database perfectly but onload, NHibernate is trying to instantiate the abstract 'StoreHours' even though I've only got a strongly type set off 'OfficeHours'
This seems like a really trivial requirement so I figure I must be doing something simple wrong. All hints appreciated.
The problem is in the way you are using the composite-id
Table-per-class works with Composite-id, but only if the composite is
implemented as a class
so you need to create a class like
public class StoreHoursCompositeId
{
public virtual Store Store { get; set; }
public virtual DayOfWeek DayOfWeek { get; set; }
// Implement GetHashCode(), is NH-mandatory
// Implement Equals(object obj), is NH-mandatory
}
In your StoreHours object create a property which use the above class (in my example I called it "StoreHoursCompositeId")
Your mapping become:
<class name="StoreHours" table="StoreHour" abstract="true" discriminator-value="0" >
<composite-id name="StoreHoursCompositeId" class="StoreHoursCompositeId">
<key-many-to-one name="Store" class="Store"
column="StoreUid"/>
<key-property name="DayOfWeek"
column="DayOfWeekId"
type="System.DayOfWeek" />
</composite-id>
<discriminator column="StoreHourType" type="Byte" />
<property name="OpenMinutes" column="OpenTime" />
<property name="CloseMinutes" column="CloseTime" />
<subclass name="OfficeHours" discriminator-value="1" />
<subclass name="AccessHours" discriminator-value="2" />
</class>
I had the very same problem and this fixed it for me.