Skip to main content

Finding database model information in Castle and ActiveRecord

Since this is my first post on the subject, let me introduce the Castle project - a .Net framework that I have been exploring recently. It has a project that tries to mimic ActiveRecord in Ruby-On-Rails, although the Castle version of ActiveRecord uses NHibernate. The good news is that an ActiveRecord class doesn't require any XML configuration or mapping files. The somewhat bad news is that you DO have to declare your classes and populate them with properties, private members and AR mapping attributes. Since I will probably use SQLServer 2000, I will just write a few queries to extract the data type and field list for each table that I want to support. More on this later.

For today, I wanted to extract the class-to-database mapping information that Castle's ActiveRecords feeds to NHibernate. I finally looked through the source code a bit and after a blind alley (NHibernate.Cfg Configuration is mostly for database connections), I ran across the ActiveRecordModel class. This has the primary key, properties, foreign keys, etc. associated with a particular class that inherits from ActiveRecordBase. I wanted to see how hard it would be to offer a generic grid view and/or form view without hand-coding a maintenance module for each form. It looks possible to me. Anyway, here is some C# code to dump the properties of a Blog (as defined in a tutorial on the Castle web site) ...


using Castle.ActiveRecord.Framework;
using Castle.ActiveRecord.Framework.Config;
using Castle.ActiveRecord.Framework.Scopes;
using Castle.ActiveRecord.Framework.Internal;

... inside your application, after calling ActiveRecordStarter.Initialize or Register ...

// get Blog's model
ActiveRecordModel blogModel = ActiveRecordModel.GetModel(typeof(Blog));
foreach (PropertyModel prop in blogModel.Properties)
{
Debug.WriteLine(prop.Property.Name + " is a " + prop.Property.PropertyType.Name);
}
Labels:

Comments

Post a Comment

Popular posts from this blog

How does Rails scaffolding select HTML input tags?

Recently, a reader saw my fix for SQL Server booleans, and asked me a followup question: why does Rails display a yes/no selection instead of a checkbox? The short answer is look in {RUBY_HOME} /lib/ruby/gems/1.8 /gems/actionpack-1.10.2 /lib/action_view/helpers, but your path may vary depending on whether you are using gem, "edge rails", etc. Anyway, look in the file "active_record_helper.rb" for a method called "all_input_tags", and notice that it calls "default_input_block" if you don't supply an input_block. Now notice that "default_input_block" creates a label and calls "input(record, column.name)" which in turn calls "InstanceTag#to_tag" which finally looks at the datatype and maps boolean to a select tag. Perhaps a wiser Rails explorer can provide us with the rationale for this, but I guess we could add a MixIn for InstanceTag that redefines the to_tag() method, or just do a dirty and unmaintainable hack l...
2 comments
Read more

Castle ActiveRecord with DetachedCriteria

My current development environment is Visual Studio Express C# Edition (read that as free ), Castle ActiveRecord's latest svn trunk(usually within a few days), and NHibernate svn trunk. As of NHibernate version 1.2.0, there is a very cool new class out there ... DetachedCriteria. This class lets you set all of your Castle relational attributes like BelongsTo, HasMany, etc. as lazy fetch, and over-ride this for searches, reports, or anytime you know ahead of time that you will be touching the related classes by calling detachedCriteria.SetFetchMode(..., FetchEnum.Eager). As a good netizen, I have tried to contribute to NHibernate and Castle ActiveRecord even if only in the smallest of ways . Oh yeah, I tried mapping to a SQL VIEW, and it worked GREAT! I received a comment after my last post, indicating that there is a better way, and I am sure of it, but the view guaranteed that I only have one database request for my dataset. NHibernate was wanting to re-fetch my missing as...
1 comment
Read more

Destiny 2 - The Corrupted Nightfall

 == Overview == This Dreaming City Nightfall is already considered one of the most irritating strikes, in part because of bugs that sometimes prevent players from proceeding to the next encounter.  Notable bugged areas are the transition from the Elevator to the Knights Steps, and after the passage, the temple sometimes doesn't reveal a way to the shadow realm where you will take your leap. Important Note: After a "de-buff" from Particle Deconstruction, shoot the boss in the head!  It is quite effective, and can melt her with some coordination. Champions: Unstoppable and Overload Shields: Arc, Solar and Void (many shields!) Don't place your well in the open where boss can snipe the sword!  She will break your super. Pass the "Relic" (Orb) twice to maximize damage. == Loadouts == General: * Add Taken spec to every weapon Titans: * Bottom Tree Solar + Path of the Burning Steps or Phoenix Cradle * Sentinal Shield + Ursa, Aeon Gauntlets Warlocks: * Stasis + Blea...
Post a Comment
Read more