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  • nHibernate strategies in a web farm

    - by Pete Nelson
    Our current project at work is a new MVC web site that will use a WCF service primarily to access a 3rd party billing system via a web service as well as a small SQL database for user personalization. The WCF service uses nHibernate for the SQL database. We'd like to implement some sort of web farm for load balancing as well as failover and maintenance. I'm trying to decide the best way to handle nHibernate's caching and database concurrency if there are multiple WCF services running. Some scenarios I've been thinking about... 1) Multiple IIS servers, one WCF server. With this setup, the WCF server would be a single point of failure, but there would be no issues with nHibernate caching or database concurrency. 2) Multiple IIS servers, each with it's own WCF service. This removes a single point of failure, but now nHibernate on one machine would not know about database changes done by another machine. Some solutions to number 2 would be to use an IStatelessSession so we're not doing any caching and nHibernate is always fetching directly from the database. This might be the most feasible as our personalization database has very few objects in it. I'm also considering a 2nd-level cache such as memcached or Velocity, but it may be overkill for this system. I'm putting this out there to see if anyone has experience doing this sort of architecture and to get some ideas for a solution. Thanks!

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  • NHibernate exception "Session is closed! Object name: 'ISession'."

    - by nrk
    Hi, I am getting the folloinwg error from NHibernate: System.ObjectDisposedException: Session is closed! Object name: 'ISession'. at NHibernate.Impl.AbstractSessionImpl.ErrorIfClosed() at NHibernate.Impl.AbstractSessionImpl.CheckAndUpdateSessionStatus() at NHibernate.Impl.SessionImpl.FireSave(SaveOrUpdateEvent event) at NHibernate.Impl.SessionImpl.Save(Object obj) I am using NHibernate in .net windows service. I am not able to trace the excact problem for the exception. This exception occurs very often. Any one can help me on this to fix this exception? Thanks nrk

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  • Querying a self referencing join with NHibernate Linq

    - by Ben
    In my application I have a Category domain object. Category has a property Parent (of type category). So in my NHibernate mapping I have: <many-to-one name="Parent" column="ParentID"/> Before I switched to NHibernate I had the ParentId property on my domain model (mapped to the corresponding database column). This made it easy to query for say all top level categories (ParentID = 0): where(c => c.ParentId == 0) However, I have since removed the ParentId property from my domain model (because of NHibernate) so I now have to do the same query (using NHibernate.Linq) like so: public IList<Category> GetCategories(int parentId) { if (parentId == 0) return _catalogRepository.Categories.Where(x => x.Parent == null).ToList(); else return _catalogRepository.Categories.Where(x => x.Parent.Id == parentId).ToList(); } The real impact that I can see, is the sql generated. Instead of a simple 'select x,y,z from categories where parentid = 0' NHibernate generates a left outer join: SELECT this_.CategoryId as CategoryId4_1_, this_.ParentID as ParentID4_1_, this_.Name as Name4_1_, this_.Slug as Slug4_1_, parent1_.CategoryId as CategoryId4_0_, parent1_.ParentID as ParentID4_0_, parent1_.Name as Name4_0_, parent1_.Slug as Slug4_0_ FROM Categories this_ left outer join Categories parent1_ on this_.ParentID = parent1_.CategoryId WHERE this_.ParentID is null Which doesn't seems much less efficient that what I had before. Is there a better way of querying these self referencing joins as it's very tempting to drop the ParentID back onto my domain model for this reason. Thanks, Ben

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  • NHibernate Transactions Best Practices

    - by Ramiro
    I have been reading about Nhibernate for a while and have been trying to use it for a site I'm implementing. I read the article by Billy McCafferty on NHibernate best practices but I did not see any indication on where is the best place to handle transactions. I thought of putting that code in the Data Access Object (DAO) but then I'm not sure how to handle cases in which more than one DAO is used. What are the best places to put transaction code in your NHibernate Application?

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  • TypeInitializationException When Getting an NHibernate Session

    - by Paul Johnson
    I’ve run into what appears to be an NHibernate config problem. Basically, I ran up a simple proof of concept persistence integration test using NUnit, the test simply querys an Oracle database and successfully returns the last record received by the underlying table. However, when the assemblies are taken out of the NUnit test environment and deployed as they would be for an actual application build, my call for an NHibernate session results in a ‘TypeInitializationException’ whilst executing the code line: sessionFactory = New Configuration().Configure().BuildSessionFactory() The application is a vb.net console app running against an Oracle 9.2 database, using a ‘coding framework’ published on the web by Bill McCafferty entitled 'NHibernate Best Practices with ASP.NET' (pre S#harp Architecture). I am running version 2.1.2.4000 of NHibernate. Any assistance much appreciated. Kind Regards Paul J.

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  • How Do I Setup NHibernate.Burrow With Fluent?

    - by CalebHC
    I'm very interested in using NHibernate.Burrow for my session handling and DAO in my ASP.NET app but I'm having trouble with the configuration. Burrow requires an XML NHibernate config for setting up its persistence but I don't have a config file since I'm using Fluent NHibernate to generate my config. So is there a way of letting Burrow know of my Fluent configuration? Hope this makes sense. Thanks

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  • How can I transfer an NHibernate PersistentGenericSet over WCF

    - by Ian Oakes
    I'm trying to send objects retrieved by NHibernate over WCF, but whenever a have a property of ICollection I get an exception. When NHibernate gets the data from the database this property is intitialized with an instance of PersistentGenericSet. Is there a way I can send a PersistentGenericSet over WCF? -or- Is there some way making NHibernate initialize these properties with another type?

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  • How can I map one to one relationship in Fluent NHibernate. I have tried everything else

    - by RM
    I have this table structure and would like to map it using Fluent Hibernate (subclass if possible). I cannot change the structure because the database has too many records and might cause major applications rework. It would be easier if the Id from Party table was a foreign key in person and organization table, but in the particular scenario the database has person and organization key as a foreign key in party table. Any help would be great. Party table Id PersonId OrganizationId Person table Id FName LName Organization table Id OrgName OrgDescription

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  • Bidirectional one-to-many associations with indexed collections in NHibernate

    - by Jørn Schou-Rode
    Last summer, I asked a question regarding how to add new object to an IList mapped as a one-to-many with NHibernate. One of the answers let me to this paragraph in the documentation: Please note that NHibernate does not support bidirectional one-to-many associations with an indexed collection (list, map or array) as the "many" end, you have to use a set or bag mapping. While I am pretty sure I understand what this paragraph says, I have no idea why or how to work around this limitation. As I am now again working with a model that seems to require a "bidirectional one-to-many association with an index collection", I figured the time was right for follow-up questions: Why does NHibernate have this limitation on associations? It is my impression that the guys behind NHibernate are quite clever, so I assume there is a pretty good reason. What are the common workarounds for this shortcoming? Making the collection a non-indexed bag and adding an explicit Position property to the child class? Any better solutions?

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  • getting proxies of the correct type in nhibernate

    - by Nir
    I have a problem with uninitialized proxies in nhibernate The Domain Model Let's say I have two parallel class hierarchies: Animal, Dog, Cat and AnimalOwner, DogOwner, CatOwner where Dog and Cat both inherit from Animal and DogOwner and CatOwner both inherit from AnimalOwner. AnimalOwner has a reference of type Animal called OwnedAnimal. Here are the classes in the example: public abstract class Animal { // some properties } public class Dog : Animal { // some more properties } public class Cat : Animal { // some more properties } public class AnimalOwner { public virtual Animal OwnedAnimal {get;set;} // more properties... } public class DogOwner : AnimalOwner { // even more properties } public class CatOwner : AnimalOwner { // even more properties } The classes have proper nhibernate mapping, all properties are persistent and everything that can be lazy loaded is lazy loaded. The application business logic only let you to set a Dog in a DogOwner and a Cat in a CatOwner. The Problem I have code like this: public void ProcessDogOwner(DogOwner owner) { Dog dog = (Dog)owner.OwnedAnimal; .... } This method can be called by many diffrent methods, in most cases the dog is already in memory and everything is ok, but rarely the dog isn't already in memory - in this case I get an nhibernate "uninitialized proxy" but the cast throws an exception because nhibernate genrates a proxy for Animal and not for Dog. I understand that this is how nhibernate works, but I need to know the type without loading the object - or, more correctly I need the uninitialized proxy to be a proxy of Cat or Dog and not a proxy of Animal. Constraints I can't change the domain model, the model is handed to me by another department, I tried to get them to change the model and failed. The actual model is much more complicated then the example and the classes have many references between them, using eager loading or adding joins to the queries is out of the question for performance reasons. I have full control of the source code, the hbm mapping and the database schema and I can change them any way I want (as long as I don't change the relationships between the model classes). I have many methods like the one in the example and I don't want to modify all of them. Thanks, Nir

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  • Count number of queries executed by NHibernate in a unit test

    - by Bittercoder
    In some unit/integration tests of the code we wish to check that correct usage of the second level cache is being employed by our code. Based on the code presented by Ayende here: http://ayende.com/Blog/archive/2006/09/07/MeasuringNHibernatesQueriesPerPage.aspx I wrote a simple class for doing just that: public class QueryCounter : IDisposable { CountToContextItemsAppender _appender; public int QueryCount { get { return _appender.Count; } } public void Dispose() { var logger = (Logger) LogManager.GetLogger("NHibernate.SQL").Logger; logger.RemoveAppender(_appender); } public static QueryCounter Start() { var logger = (Logger) LogManager.GetLogger("NHibernate.SQL").Logger; lock (logger) { foreach (IAppender existingAppender in logger.Appenders) { if (existingAppender is CountToContextItemsAppender) { var countAppender = (CountToContextItemsAppender) existingAppender; countAppender.Reset(); return new QueryCounter {_appender = (CountToContextItemsAppender) existingAppender}; } } var newAppender = new CountToContextItemsAppender(); logger.AddAppender(newAppender); logger.Level = Level.Debug; logger.Additivity = false; return new QueryCounter {_appender = newAppender}; } } public class CountToContextItemsAppender : IAppender { int _count; public int Count { get { return _count; } } public void Close() { } public void DoAppend(LoggingEvent loggingEvent) { if (string.Empty.Equals(loggingEvent.MessageObject)) return; _count++; } public string Name { get; set; } public void Reset() { _count = 0; } } } With intended usage: using (var counter = QueryCounter.Start()) { // ... do something Assert.Equal(1, counter.QueryCount); // check the query count matches our expectations } But it always returns 0 for Query count. No sql statements are being logged. However if I make use of Nhibernate Profiler and invoke this in my test case: NHibernateProfiler.Intialize() Where NHProf uses a similar approach to capture logging output from NHibernate for analysis via log4net etc. then my QueryCounter starts working. It looks like I'm missing something in my code to get log4net configured correctly for logging nhibernate sql ... does anyone have any pointers on what else I need to do to get sql logging output from Nhibernate?

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  • TypeInitilazationException When Getting an NHibernate Session

    - by Paul Johnson
    I’ve run into what appears to be an NHibernate config problem. Basically, I ran up a simple proof of concept persistence integration test using NUnit, the test simply querys an Oracle database and successfully returns the last record received by the underlying table. However, when the assemblies are taken out of the NUnit test environment and deployed as they would be for an actual application build, my call for an NHibernate session results in a ‘TypeInitializationException’ whilst executing the code line: sessionFactory = New Configuration().Configure().BuildSessionFactory() The application is a vb.net console app running against an Oracle 9.2 database, using a ‘coding framework’ published on the web by Bill McCafferty entitled 'NHibernate Best Practices with ASP.NET' (pre S#harp Architecture). I am running version 2.1.2.4000 of NHibernate. Any assistance much appreciated. Kind Regards Paul J.

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  • Multiple database with NHibernate

    - by Flint
    Hi, I have two databases. One from Oracle 10g. Another from Mysql. I have configured my web application with Nhibernate for Oracle and now I am in need of using the MySQL database. So how can i configure the hibernate.cfg.xml so that i can use both of the database at the same application? My current hibernate.cfg.xml is: <?xml version="1.0" encoding="utf-8" ?> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> <property name="connection.driver_class">NHibernate.Driver.OracleClientDriver</property> <property name="connection.connection_string">Data Source=xe;Persist Security Info=True;User ID=hr;Password=hr;Unicode=True</property> <property name="show_sql">false</property> <property name="dialect">NHibernate.Dialect.Oracle9Dialect</property> <!-- mapping files --> <mapping assembly="DataTransfer" /> </session-factory> </hibernate-configuration>

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  • Identifying NHibernate proxy classes

    - by Marc Gravell
    I'm not an NHibernate user; I write a serialization utility library. A user has logged a feature-request that I should handle NHibernate proxy classes, treating them the same as the actual type. At the moment my code is treating them as unexpected inheritance, and throwing an exception. The code won't know in advance about NHibernate (including no reference, but I'm not aftaid of reflection ;-p) Is there a robust / guaranteed way of detecting such proxy types? Apparently DataContractSerializer handles this fine, so I'm hoping it is something pretty simple. Perhaps some interface or [attribute] decoration. Also, during deserialization; at the moment I would be creating the original type (not the NHibernate type). Is this fine for persistence purposes? Or is the proxy type required? If the latter; what is required to create an instance of the proxy type?

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  • NHibernate stored procedure problem

    - by Calvin
    I'm having a hard time trying to get my stored procedure works with NHibernate. The data returned from the SP does not correspond to any database table. This is my mapping file: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="DomainModel" namespace="DomainModel.Entities"> <sql-query name="DoSomething"> <return class="SomeClass"> <return-property name="ID" column="ID"/> </return> exec [dbo].[sp_doSomething] </sql-query> </hibernate-mapping> Here is my domain class: namespace DomainModel.Entities { public class SomeClass { public SomeClass() { } public virtual Guid ID { get; set; } } } When I run the code, it fails with Exception Details: NHibernate.HibernateException: Errors in named queries: {DoSomething} at line 80 Line 78: config.Configure(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "NHibernate.config")); Line 79: Line 80: g_sessionFactory = config.BuildSessionFactory(); When I debug into NHibernate code, it seems that SomeClass is not added to the persister dictionary because there isn't a class mapping (only sql-query) defined in hbm.xml. And later on in CheckNamedQueries function, it is not able to find the persistor for SomeClass. I've checked all the obvious things (e.g. make hbm as an embedded resource) and my code isn't too much different from other samples I found on the web, but somehow I just can't get it working. Any idea how I can resolve this issue?

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  • NHibernate unintential lazy property loading

    - by chiccodoro
    I introduced a mapping for a business object which has (among others) a property called "Name": public class Foo : BusinessObjectBase { ... public virtual string Name { get; set; } } For some reason, when I fetch "Foo" objects, NHibernate seems to apply lazy property loading (for simple properties, not associations): The following code piece generates n+1 SQL statements, whereof the first only fetches the ids, and the remaining n fetch the Name for each record: ISession session = ...IQuery query = session.CreateQuery(queryString); ITransaction tx = session.BeginTransaction(); List<Foo> result = new List<Foo>(); foreach (Foo foo in query.Enumerable()) { result.Add(foo); } tx.Commit(); session.Close(); produces: NHibernate: select foo0_.FOO_ID as col_0_0_ from V1_FOO foo0_ NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 81 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36470 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36473 Similarly, the following code leads to a LazyLoadingException after session is closed: ISession session = ... ITransaction tx = session.BeginTransaction(); Foo result = session.Load<Foo>(id); tx.Commit(); session.Close(); Console.WriteLine(result.Name); Following this post, "lazy properties ... is rarely an important feature to enable ... (and) in Hibernate 3, is disabled by default." So what am I doing wrong? I managed to work around the LazyLoadingException by doing a NHibernateUtil.Initialize(foo) but the even worse part are the n+1 sql statements which bring my application to its knees. This is how the mapping looks like: <class name="Foo" table="V1_FOO"> ... <property name="Name" column="NAME"/> </class> BTW: The abstract "BusinessObjectBase" base class encapsulates the ID property which serves as the internal identifier.

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  • What classes should I map against with NHibernate?

    - by apollodude217
    Currently, we use NHibernate to map business objects to database tables. Said business objects enforce business rules: The set accessors will throw an exception on the spot if the contract for that property is violated. Also, the properties enforce relationships with other objects (sometimes bidirectional!). Well, whenever NHibernate loads an object from the database (e.g. when ISession.Get(id) is called), the set accessors of the mapped properties are used to put the data into the object. What's good is that the middle tier of the application enforces business logic. What's bad is that the database does not. Sometimes crap finds its way into the database. If crap is loaded into the application, it bails (throws an exception). Sometimes it clearly should bail because it cannot do anything, but what if it can continue working? E.g., an admin tool that gathers real-time reports runs a high risk of failing unnecessarily instead of allowing an admin to even fix a (potential) problem. I don't have an example on me right now, but in some instances, letting NHibernate use the "front door" properties that also enforce relationships (especially bidi) leads to bugs. What are the best solutions? Currently, I will, on a per-property basis, create a "back door" just for NHibernate: public virtual int Blah {get {return _Blah;} set {/*enforces BR's*/}} protected virtual int _Blah {get {return blah;} set {blah = value;}} private int blah; I showed the above in C# 2 (no default properties) to demonstrate how this gets us basically 3 layers of, or views, to blah!!! While this certainly works, it does not seem ideal as it requires the BL to provide one (public) interface for the app-at-large, and another (protected) interface for the data access layer. There is an additional problem: To my knowledge, NHibernate does not give you a way to distinguish between the name of the property in the BL and the name of the property in the entity model (i.e. the name you use when you query, e.g. via HQL--whenever you give NHibernate the name (string) of a property). This becomes a problem when, at first, the BR's for some property Blah are no problem, so you refer to it in your O/R mapping... but then later, you have to add some BR's that do become a problem, so then you have to change your O/R mapping to use a new _Blah property, which breaks all existing queries using "Blah" (common problem with programming against strings). Has anyone solved these problems?!

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  • How to add a WHERE clause on the second table of a 1-to-1 join in Fluent NHibernate?

    - by daddywoodland
    I'm using a legacy database that was 'future proofed' to keep track of historical changes. It turns out this feature is never used so I want to map the tables into a single entity. My tables are: CodesHistory (CodesHistoryID (pk), CodeID (fk), Text) Codes (CodeID (pk), CodeName) To add an additional level of complexity, these tables hold the content for the drop down lists throughout the application. So, I'm trying to map a Title entity (Mr, Mrs etc.) as follows: Title ClassMap - Public Sub New() Table("CodesHistory") Id(Function(x) x.TitleID, "CodesHistoryID") Map(Function(x) x.Text) 'Call into the other half of the 1-2-1 join in order to merge them in 'this single domain object Join("Codes", AddressOf AddTitleDetailData) Where("CodeName like 'C.Title.%'") End Sub ' Method to merge two tables with a 1-2-1 join into a single entity in VB.Net Public Sub AddTitleDetailData(ByVal m As JoinPart(Of Title)) m.KeyColumn("CodeID") m.Map(Function(x) x.CodeName) End Sub From the above, you can see that my 'CodeName' field represents the select list in question (C.Title, C.Age etc). The problem is that the WHERE clause only applies to the 'CodesHistory' table but the 'CodeName' field is in the 'Codes' table. As I'm sure you can guess there's no scope to change the database. Is it possible to apply the WHERE clause to the Codes table?

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  • NHibernate and objects with value-semantics

    - by Groo
    Problem: If I pass a class with value semantics (Equals method overridden) to NHibernate, NHibernate tries to save it to db even though it just saved an entity equal by value (but not by reference) to the database. What am I doing wrong? Here is a simplified example model for my problem: Let's say I have a Person entity and a City entity. One thread (producer) is creating new Person objects which belong to a specific existing City, and another thread (consumer) is saving them to a repository (using NHibernate as DAL). Since there is lot of objects being flushed at a time, I am using Guid.Comb id's to ensure that each insert is made using a single SQL command. City is an object with value-type semantics (equal by name only -- for this example purposes only): public class City : IEquatable<City> { public virtual Guid Id { get; private set; } public virtual string Name { get; set; } public virtual bool Equals(City other) { if (other == null) return false; return this.Name == other.Name; } public override bool Equals(object obj) { return Equals(obj as City); } public override int GetHashCode() { return this.Name.GetHashCode(); } } Fluent NH mapping is something like: public class PersonMap : ClassMap<Person> { public PersonMap() { Id(x => x.Id) .GeneratedBy.GuidComb(); References(x => x.City) .Cascade.SaveUpdate(); } } public class CityMap : ClassMap<City> { public CityMap() { Id(x => x.Id) .GeneratedBy.GuidComb(); Map(x => x.Name); } } Right now (with my current NHibernate mapping config), my consumer thread maintains a dictionary of cities and replaces their references in incoming person objects (otherwise NHibernate will see a new, non-cached City object and try to save it as well), and I need to do it for every produced Person object. Since I have implemented City class to behave like a value type, I hoped that NHibernate would compare Cities by value and not try to save them each time -- i.e. I would only need to do a lookup once per session and not care about them anymore. Is this possible, and if yes, what am I doing wrong here?

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  • NHibernate auditing in disconnected mode

    - by Ciaran
    I'm developing an app with a Silverlight UI, transferring my domain objects over WCF and persisting them via NHibernate. I'm therefore working with NHibernate in a disconnected mode. I'm already using the NHibernate PreUpdate and PreInsert EventListeners to perform some metadata operations (updating Create/Update date, created/updated by etc) and they are working fine. I now have a requirement to perform data logging on some of my domain objects. So I will need to have an audit table that has a before-save and after-save state of certain entities. I had wanted to use the @event.Persister.OldState and @event.Persister.NewState to perform this logging, but because I am in a disconnected scenario (using different Sessions from when data is retrieved to when it is persisted), @event.Persister.OldState is null when I am saving my changes back to the database. How is anyone else doing data logging in a disconnected scenario with NHibernate?

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  • How to query across many-to-many association in NHibernate?

    - by Splash
    I have two entities, Post and Tag. The Post entity has a collection of Tags which represents a many-to-many join between the two (that is, each post can have any number of tags and each tag can be associated with any number of posts). I am trying to retrieve all Posts which have a given tag. However, I seem to be unable to get this query right. I essentially want something which means the same as the following pseudo-HQL: from Posts p where p.Tags contains (from Tags t where t.Name = :tagName) order by p.DateTime The only thing I've found which even approaches this is a post by Ayende. However, his approach requires the entity on the other side (in my case, Tag) to have a collection showing the other end of the many-to-many. I don't have this and don't really wish to have it. I find it hard to believe this can't be done. What am I missing? My entities & mappings look like this (simplified): public class Post { public virtual int Id { get; set; } public virtual string Title { get; set; } private IList<Tag> tags = new List<Tag>(); public virtual IEnumerable<Tag> Tags { get { return tags; } } public virtual void AddTag(Tag tag) { this.tags.Add(tag); } } public class PostMap : ClassMap<Post> { public PostMap() { Id(x => x.Id).GeneratedBy.HiLo("99"); Map(x => x.Title); HasManyToMany(x => x.Tags); } } // ---- public class Tag { public virtual int Id { get; set; } public virtual string Name { get; set; } } public class TagMap : ClassMap<Tag> { public TagMap () { Id(x => x.Id).GeneratedBy.HiLo("99"); Map(x => x.Name).Unique(); } }

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