Thursday, March 08, 2007

Castle ActiveRecord calling a Stored Procedure

Update: I have contributed patch AR-156 that allows full integration of Insert, Update and Delete to ActiveRecord models.

If you've been reading my blog lately, you know that I have been seriously testing the Castle ActiveRecord framework out. I really love it, but I have an existing Microsoft SQL Server database with many stored procedures in it. I have tested the ActiveRecord model out, and I am sure that I will learn enough to be able to use it for standard CRUD (create, read, update, delete aka. insert, select, update, delete) functionality. BUT ... If I really want to integrate with my existing billing
procedures, etc, I will have to be able to call stored procedures. I have taken
two approaches ...
  1. write the ARHelper.ExecuteNonQuery(targetType, dmlString) method that gets a connection for the supplied type, executes dmlString, and closes it.

  2. write the ARHelper.RegisterCustomMapping(targetType, xmlString) method that allows me to add mappings that refer to my auto-generated Castle objects. Otherwise, the sql query or procedure would have to return scalars.

Any sql-query registered with the RegisterCustomMapping method below MUST return something, according to the documentation (I use Hibernate v3 documentation alot, and check NHibernate when things do not work). For calls that do not return anything (other than a count of records affected), look at my ExecuteNonQuery method.


SAMPLE USAGE CODE
Type targetType = typeof(Status);
string customMap = "<sql-query> ...";
ARHelper.RegisterCustomMapping(targetType, customMap);
ISessionFactoryHolder holder = ActiveRecordMediator.GetSessionFactoryHolder();
ISession sess = holder.CreateSession(targetType);
try
{
string sqlProc = "Test_ActivationStatus_SP";
IQuery query = sess.GetNamedQuery(sqlProc);
IList list = (IList)query.List();

foreach (object obj in list)
{
Debug.WriteLine(String.Format("{0}", obj.ToString()));
}
}
finally
{
holder.ReleaseSession(sess);
}



LIBRARY CODE
using Castle.ActiveRecord;
using Castle.ActiveRecord.Framework;
using Castle.ActiveRecord.Framework.Config;

using NHibernate;
using NHibernate.Cfg;
using NHibernate.Expression;

... namespace and class declarations go here ...

// returns number of records affected
protected internal static int ExecuteNonQuery(Type targetType, string dml)
{
ISessionFactoryHolder holder = ActiveRecordMediator.GetSessionFactoryHolder();
NHibernate.ISession session = holder.CreateSession(targetType);
int rowsAffected = -1;
IDbConnection conn = null;
IDbCommand cmd = null;

try
{
conn = session.Connection;
cmd = conn.CreateCommand();
cmd.CommandText = dml;
cmd.CommandType = CommandType.Text;
rowsAffected = cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
throw new ActiveRecordException("Could not perform ExecuteNonQuery for "
+ targetType.Name, ex);
}
finally
{
if (cmd != null) cmd.Dispose();
holder.ReleaseSession(session);
}

//TODO: assert statement contains "INSERT", "UPDATE" or "EXEC"
return rowsAffected;
}

/*
* Sample Custom Mapping to call a stored procedure ...
* "<sql-query name='Test_Status_SP'>" +
* "<return class='Status'/>" +
* //"select * from dbo.LStatus" +
* "EXEC dbo.MyApp_Get_KeyValue 'dbo.LStatus', 0, 0" +
* "</sql-query>*/
public static void RegisterCustomMapping(
Type targetType,
string mapping_hbm_xml
)
{
ISessionFactoryHolder holder = ActiveRecordMediator.GetSessionFactoryHolder();
Configuration config = holder.GetConfiguration(holder.GetRootType(targetType));

// auto-build <hibernate-mapping> wrapper element,
// so user does not need to maintain this
mapping_hbm_xml = "<hibernate-mapping xmlns='"
+ Configuration.MappingSchemaXMLNS + "'"
+ " assembly='" + targetType.Assembly.FullName + "'"
+ " namespace='" + targetType.Namespace + "'>\n" + mapping_hbm_xml
+ "\n</hibernate-mapping>";

config.AddXmlString(mapping_hbm_xml);
}

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2 Comments:

Blogger kvieres said...

cant this method work with Oracle?

December 09, 2008 1:24 AM  
Blogger Roy Tate said...

I do not see any reason why this solution would be limited to Microsoft SQL Server. This patch was never accepted by the Castle developers. In another patch, I hacked support for ActiveRecord objects that called stored procedures for Add, Update and Delete methods, but it required a hack to NHibernate, since they don't expose a clean parameter list.

December 09, 2008 8:50 AM  

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