>From a purely NHib viewpoint, you don't need to persist the computed value. You can map a formula like so and then you can use it in your Linq specifications just like any other property:
<property name="FullName" formula="FirstName + ' ' + LastName" /> I don't know how this would (could?) get mapped in FNH <blush/> The other option is to shift the computation into your database, but that depends on your RDBMS. SQL Server is capable of supporting computed columns on a table, so I would expect most others could too. Note: both of these options could map into a straightforward property on your class, but then you won't get the FullName property updating in response to a change on the FirstName property. If you need that, then you'll need to code it up within your class. Cheers, John On Jun 18, 12:32 am, Kurt Johnson <[email protected]> wrote: > I think I got it. I missed the entire concept of persisting the > property result as the end-game. I was expecting NHibernate.Linq to > translate some expression tree of my FullName property into a criteria > for me. > > I finally understand the concept, yet I am bit bummed. Maybe there is > some futuristic alien race that has a library for my desired code- > witchery (or, I can get cracking on my own patch). > > Disappointed but now back-on-board, I went ahead and mapped the above > property FullName (after adding an empty setter) accordingly with a > SetAttribute for "access" as "readonly". > > Now, my updates to my FirstName and LastName are persisting to the > database the FullName column. Also, I am able to query that column in > the database. > > Thanks again, Hudson. That was precisely what I needed! > > On Jun 17, 8:59 am, Hudson Akridge <[email protected]> wrote: > > > > > > It sounds like my virtual method needs to be mapped with a readonly > > > accessor (?) so that it doesn't go out to via nhib in outgoing DDL, > > > but can be interpreted by the HQL parser in selects. Am I on the right > > > track? > > > Yup, you're on the right track :) But it's the inbound nhib that you're > > looking to avoid (the rehydration part) Basically the ReadOnlyAccessor > > allows NHibernate to persist the value, but not retrieve it. However, that > > value is stored in the database, and thus, available for HQL queries, which > > is really just a DSL that sits on top of SQL. > > > Think of it like this. If it's not available in SQL to write a query by > > hand, then it's not available for HQL. ReadOnlyAccessor gives you the > > optimization of saying that this property will only ever be queried on, so > > persist it into the DB, but the DB is not used to evaluate the value in the > > domain model. > > > On Wed, Jun 17, 2009 at 8:55 AM, Kurt Johnson <[email protected]> wrote: > > > > Thanks for the reply, Hudson. > > > > I will take a look at the NHibernate docs and try and implement that. > > > It sounds like my virtual method needs to be mapped with a readonly > > > accessor (?) so that it doesn't go out to via nhib in outgoing DDL, > > > but can be interpreted by the HQL parser in selects. Am I on the right > > > track? > > > > I was thinking that the conversion from Linq\POCO would occur first -- > > > via an expression tree -- then, translated to HQL as the concatention > > > of the two fields. > > > > So much to learn... and I love it. > > > > Thanks again, > > > Kurt > > > > On Jun 16, 2:12 pm, Hudson Akridge <[email protected]> wrote: > > > > Your question isn't specifically a fluent way that I'm aware of, you're > > > just > > > > looking for a way to map a model formula property to the database, for > > > > querying, but that doesn't get read out of the database (because again, > > > it's > > > > calculated in the model based on the other two properties). Is that > > > correct? > > > > In NHibernate, look at mapping the FullName property using a: > > > > access="NHibernate.Properties.ReadOnlyAccessor, NHibernate" > > > > > Attribute. The ReadOnlyAccessor may be exactly what you want there. > > > > > I don't have the source of fluent available to me right now, but I don't > > > > believe we currently support the ReadOnlyAccessor, so you might be stuck > > > > setting that manually with SetAttribute for now (although expect that > > > method > > > > to go away here soon in trunk), or you can just modify your version of > > > FNH > > > > to support that. > > > > > On Tue, Jun 16, 2009 at 12:56 PM, kujotx <[email protected]> wrote: > > > > > > I have a derived class that uses a method from a value object. My > > > > > value object has first, last names, so I added a concatenation for > > > > > full name and other variations for Find() criteria. > > > > > > The abbreviated version is shown below. My goal is to be able to do > > > > > something like the following p => p.Person.FullName.Contains("John > > > > > Doe"); > > > > > > I am using Nhibernate.Linq and Linq.Specifications. I was trying to > > > > > write a specification that included the > > > > > > That fails. Is there a fluent nhibernate way that I can accomplish > > > > > this, or will the solution lie more in nhibernate? > > > > > > Thanks, > > > > > > Kurt > > > > > > <code> > > > > > public class User : AbstractUser{ > > > > > } > > > > > > public abstract AbstractUser > > > > > { > > > > > public virtual Person Person {get; private set:} > > > > > } > > > > > > public class Person{ > > > > > public virtual string LastName {get; private set;} > > > > > public virtual string FirstName {get; private set;} > > > > > > public Person (string firstName, string lastName){ > > > > > FirstName = firstName; > > > > > LastName = lastName; > > > > > } > > > > > > public string FullName{ > > > > > get{ > > > > > return string.Format("{0} {1}, FirstName, > > > > > LastName"); > > > > > } > > > > > } > > > > > } > > > > > </code> > > > > > -- > > > > - Hudsonhttp://www.bestguesstheory.comhttp://twitter.com/HudsonAkridge > > > -- > > - Hudsonhttp://www.bestguesstheory.comhttp://twitter.com/HudsonAkridge- > > Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Fluent NHibernate" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/fluent-nhibernate?hl=en -~----------~----~----~----~------~----~------~--~---
