nHibernate is giving the error : Custom type does not implement UserCollectionType: myApp.Domain.OrderLineCollection.
BindingList implements IList, so why is nHibernate trying to use UserCollectionType instead of IList?
public class OrderHeader
{
public virtual int OrderHeaderId { get; set; }
public virtual string OrderNumber { get; set; }
public virtual OrderLineCollection Line { get; set; }
}
public class OrderLineCollection : BindingList<OrderHeader> { }
public class OrderHeaderMap : ClassMap<OrderHeader>
{
public OrderHeaderMap()
{
WithTable("Orders");
Id(x => x.OrderHeaderId, "OrderId").GeneratedBy.Identity();
Map(x => x.OrderNumber);
HasMany(x => x.Line).WithKeyColumn("OrderHeaderId").AsList();
}
}
<list name="Line">
<key column="OrderHeaderId" />
<index />
<one-to-many class="myApp.Domain.OrderLine, myApp.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
</list>
NHibernate has it's own custom typed list which implements IList underneath.
I'm afraid you won't be able to use yours without creating nHibernate UserType.
But i might be wrong and would be glad to hear why. :)
You might want to check the XML that's created by fluentNHibernate - it's quite possible they take the type of the Line property and set it explicitly.
This should work if you don't set the type explicitly. I tried implementing a custom collection deriving from IList - and it worked when I didn't specify the type on the bag/list whatever in the mapping.
Ok, I did a quick test Arnis L. is right - it probably won't work without implementing UserCollectionType. In my experience, it's a pain to implement .
(somehow I remembered doing something like this but I guess my mind's playing tricks on me)
I look at the NHibernate source code and at least for PersistentBag and PersistentList NHibernate will instanciate a ArrayList object as the back end list, not a OrderLineCollection as one could thought. When you implement IUserColletionType there is a method who tells NHibernate what collection it should create, and also what Persistent collection Hibernate should use to sav. Take a look at this link might help a lot. But I still cant do Nhibernate work with BindingList.
Related
I have two objects, Case and Note. A Case can have gobs of Notes, like, in the thousands. We are trying to load them asynchronously, in batches, and stream them to the UI so there is no delay waiting for them all to load.
The class/mappings are
public class Case
{
public virtual IList<Note> Notes { get; protected set; }
}
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="SCMS.TAMS.BusinessEntities" namespace="SCMS.TAMS.BusinessEntities">
<class name="Case" table="Cases">
<bag name="Notes" inverse="true" cascade="all" lazy="true">
<key column="CaseID" />
<one-to-many class="Note" />
</bag>
</class>
</hibernate-mapping>
public class Note
{
public virtual Case Case {get; set;}
public virtual long CaseId {get; set;}
}
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="SCMS.TAMS.BusinessEntities" namespace="SCMS.TAMS.BusinessEntities" default-lazy="true">
<class name="Note" table="CaseNotes">
<many-to-one name="Case" column="CaseID"/>
<property name="CaseId" column="CaseID" />
</class>
</hibernate-mapping>
Now, when I call
NHibernateSession.Query<Note>().Where(n => n.CaseId == 123).Skip(0).Take(10).ToList();
to load the first 10 Notes for Case 123, the thing loads the Case object, which takes about 30 seconds because there's lots of other things on it, and other logic when it gets loaded, etc., none of which I need/want at this time. All I want/need are the 10 Notes.
I've tried all sorts of variations on this mapping and none of them have worked. What am I doing wrong here?
How are you using this query? is it some thing for the UI? liking showing in a grid or something? or are you performing business logic in a component?
Either way you want to project into another object. Your query right now returns a list of notes which is then going to load that parent object per the mappings.
So if you are using this query to send the information to the UI of an asp.net mvc application, project directly into your view model
NHibernateSession.Query<Note>().Where(n => n.CaseId == 123).Select(n => new SomeViewModel { Prop1 = n.Prop1, Prop2 = n.Prop2 ...}).Skip(0).Take(10).ToList();
or create an anonymous object
NHibernateSession.Query<Note>().Where(n => n.CaseId == 123).Select n => new { n.Prop1, n.Prop2, ...}).Skip(0).Take(10).ToList();
This will keep the parent object from loading. It also has the added benefit that you are only querying the information you need because the query be limited to the data you are projecting.
Important to know is that if all above is true...
this is the real mapping (which is not it is just an obvious extract)
<class name="Note" table="CaseNotes">
<many-to-one name="Case" column="CaseID"/>
...
this is the class (again extract without ID)
public class Note
{
public virtual Case Case {get; set;}
public virtual long CaseId {get; set;}
}
and that would be a UNIT TEST statement to load notes:
var list = NHibernateSession
.Query<Note>()
.Where(n => n.CaseId == 123)
.Skip(0).Take(10)
.ToList();
then NHibernate will NEVER load the Case object. Never. Because:
NHibernate is lazy, just live with it
The reason, the trigger to load related reference (Case property) must be something explicit.
Mostly:
there is usage of the Case object somewhere. E.g. in override of the GetHashCode() the Case.ID is used
Or:
there is a serialization or DTO conversion which does touch the Case property
In those case, NHibernate must load that...
So, create few unit tests with basic queries and assure that your the is really as shown above. Then it will work as expected
I have a class which I would like to map as a component onto any table which contains it:
public class Time
{
public int Hours { get; set; }
public int Minutes { get; set; }
public int Seconds { get; set; }
}
I would like to store this class as a bigint in the database - the same as how TimeSpan is stored but my class has completely different behaviour so I decided to create my own.
I'm using FLH's automapper and have this class set as a component (other classes have Time as a property). I've got as far as creating an override but am not sure how to go about mapping it:
I gave it a try this way:
public class TimeMappingOverride : IAutoMappingOverride<Time>
{
public void Override(AutoMapping<Time> mapping)
{
mapping.Map(x => x.ToTimeSpan());
mapping.IgnoreProperty(x => x.Hours);
mapping.IgnoreProperty(x => x.Minutes);
mapping.IgnoreProperty(x => x.Seconds);
}
}
But got this error:
Unable to cast object of type 'System.Linq.Expressions.UnaryExpression' to type 'System.Linq.Expressions.MethodCallExpression'.
How should I go about this?
Details of components can be found here: http://wiki.fluentnhibernate.org/Fluent_mapping#Components
But first of all, you can't map a method.
Assuming you change ToTimeSpan() to a property AsTimeSpan, there are two ways to do it, only the harder of which will work for you because you are using automapping:
Create a ComponentMap<Time> -- once done, your existing mapping will just work. This is not compatible with automapping.
Declare the component mapping inline:
mapping.Component(x => x.AsTimeSpan, component => {
component.Map(Hours);
component.Map(Minutes);
component.Map(Seconds);
});
You'll have to do this every time, though.
Of course, this doesn't address "I would like to store this class as bigint…"
Are you saying you want to persist it as seconds only? If so, scratch everything at the top and again you have two options:
Implement NHibernate IUserType (ugh)
Create a private property or field that stores the value as seconds only, and wire only this up to NHibernate. The getters and setters of the pubic properties will have to convert to/from seconds.
I personally haven't worked with AutoMappings yet, but my suggestion would be to look into NHibernate's IUserType to change how a type is being persisted. I believe that's a cleaner way of defining your custom mapping of Time <-> bigint.
Reading the code above, Map(x => x.ToTimeSpan()) will not work as you cannot embed application-to-database transformation code into your mappings. Even if that would be possible, the declaration misses the transformation from the database to the application. A IUserType, on the other hand, can do custom transformations in the NullSafeGet and NullSafeSet methods.
I just had a NHibernate related problem where I forgot to map one property of a class.
A very simplified example:
public class MyClass
{
public virtual int ID { get; set; }
public virtual string SomeText { get; set; }
public virtual int SomeNumber { get; set; }
}
...and the mapping file:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyAssembly"
namespace="MyAssembly.MyNamespace">
<class name="MyClass" table="SomeTable">
<property name="ID" />
<property name="SomeText" />
</class>
</hibernate-mapping>
In this simple example, you can see the problem at once:
there is a property named "SomeNumber" in the class, but not in the mapping file.
So NHibernate will not map it and it will always be zero.
The real class had a lot more properties, so the problem was not as easy to see and it took me quite some time to figure out why SomeNumber always returned zero even though I was 100% sure that the value in the database was != zero.
So, here is my question:
Is there some simple way to find this out via NHibernate?
Like a compiler warning when a class is mapped, but some of its properties are not.
Or some query that I can run that shows me unmapped properties in mapped classes...you get the idea.
(Plus, it would be nice if I could exclude some legacy columns that I really don't want mapped.)
EDIT:
Okay, I looked at everything you proposed and decided to go with the meta-data API...that looks the easiest to understand for me.
Now that I know what to search for, I found some examples which helped me to get started.
So far, I have this:
Type type = typeof(MyClass);
IClassMetadata meta = MySessionFactory.GetClassMetadata(type);
PropertyInfo[] infos = type.GetProperties();
foreach (PropertyInfo info in infos)
{
if (meta.PropertyNames.Contains(info.Name))
{
Console.WriteLine("{0} is mapped!", info.Name);
}
else
{
Console.WriteLine("{0} is not mapped!", info.Name);
}
}
It nearly works, except one thing:
IClassMetadata.PropertyNames returns the names of all the properties except the ID.
To get the ID, I have to use IClassMetadata.IdentifierPropertyName.
Yes, I could save .PropertyNames in a new array, add .IdentifierPropertyName to it and search that array.
But this looks strange to me.
Is there no better way to get all mapped properties including the ID?
You could use the NHibernate meta-data API to find the mapped properties, and reflection to find all the properties.
Edit No, there isn't any other way list all the properties including the id. It isn't that hard to use:
foreach (PropertyInfo info in infos)
{
if (meta.PropertyNames.Contains(info.Name) || info.Name = meta.IdentifierPropertyName)
{
Console.WriteLine("{0} is mapped!", info.Name);
}
else
{
Console.WriteLine("{0} is not mapped!", info.Name);
}
}
There are two tools I'm aware of that can help with this:
Fluent NHibernate persistence specification testing
Nhibernate Ghostbuster
but they don't specifically address the problem you had with an unmapped property. The best solution is to write good unit tests that ensure that the properties you want to persist are persisted correctly. It's tedious but necessary.
The story:
I had class User and class Organization: User. I did not use any mappings for these classes, let FNH do mapping automatically. Then, I added
public class OrganizationMap : IAutoMappingOverride<Organization>
{
public void Override(AutoMap<Organization> mapping)
{
}
}
Notice there're no overrides. So I did not expect any changes in FNH behavior. But I got this (during schema export actually):
NHibernate.MappingException:
(XmlDocument)(2,4): XML validation
error: The element 'class' in
namespace 'urn:nhibernate-mapping-2.2'
has incomplete content. List of
possible elements expected: 'meta,
subselect, cache, synchronize,
comment, tuplizer, id, composite-id'
in namespace
'urn:nhibernate-mapping-2.2'.
The generated Orders.Core.Organization.hbm.xml was really empty:
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-access="">
<class name="Orders.Core.Organization, Orders.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" table="Organizations" xmlns="urn:nhibernate-mapping-2.2" />
</hibernate-mapping>
So, after I reviewed the User.hbm I got the idea - I need to override Organization in the base class like this:
public class UserMap : IAutoMappingOverride<User>
{
public void Override(AutoMap<User> mapping)
{
mapping.JoinedSubClass<Organization>("ColumnId", m => {...}
);
}
}
But, I would better like to do this in a separate mapping override class for Organization... after all, what would the mapping become if I have 5 subclasses all in single Override method.
Is this possible?
Your override is telling FNH that you will manually write the mappings for that class. The error you are getting is because there is nothing being mapped for Organisation (if you look at the generated HBM.xml it will be empty).
What exactly are you wanting to write the override for?
Edit:
In that case, you can do something like this:
public class MyAlteration : IAutoMappingAlteration
{
public void Alter(AutoPersistenceModel model)
{
model.ForTypesThatDeriveFrom<User>(
map => map.HasMany<User>( x => x.Children)
);
}
}
And when configuring fluent nhibernate:
model.Alteration( a => a.Add<MyAlteration>());
Note: This is using the latest codebase of fluent nhibernate (1.0RC).
Turned out that with latest FNH (some revision after RC) this is possible now. I wonder if this is because I asked ;-)
So I had this
mapping.JoinedSubClass<Organization>("UserId", m =>
{
m.HasMany(x => x.Currencies).Element("Currency").AsBag();
}
);
and it stopped working after upgrading to RC. Then I moved this into its own class
public class OrganizationMap : IAutoMappingOverride<Organization>
{
public void Override(AutoMapping<Organization> mapping)
{
mapping.HasMany(x => x.Currencies).Element("Currency").AsBag();
}
}
it started to work again. Just like I wanted! Now I don't even need to indicate JoinedSubClass as this is the default, anyway. I can just override my subclass properties which is cool.
Though it wasn't too easy to figure out why NH started to complain about association of strings... I even thought that .Element is broken in RC. I wonder why JoinedSubClass still has this mapping part if it doesn't completely work.
Suppose I have this class:
public class GroceryListItem()
{
public GroceryList { get; private set; }
public GroceryListItem(GroceryList groceryList)
{
GroceryList = groceryList;
}
}
What is the NHibernate mapping file access strategy for this scenario? (i.e. <one-to-many name="GroceryList" column="XXX" access="?????" />)
It turns out the answer is pretty simple -- no special access is required. NHibernate is smart enough to work this out on its own. In other words, the code in my question works correctly with the following line in the mapping file:
<one-to-many name="GroceryList" column="XXX" />
Use access="readonly" in the newer versions, or create your own PropertyAccessor or use any of the other approaches described here:
http://blog.schuager.com/2008/12/nhibernate-read-only-property-access.html