CRM 2011 Online Plugin works fine but no Update committed - plugins

Question

I'm a new developper in CRM 2011. I've made that simple code for tests.
It appears that the plugin works fine (checked with the ITracingService) but it seems that the attributes doesn't take the new values.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xrm.Sdk.Query;
using Microsoft.Xrm.Sdk;
namespace AgeUpdatePlugin
{
public class AgeUpdatePlugin:IPlugin
{
public void Execute(IServiceProvider serviceProvider)
{
IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
try
{
IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
ITracingService tracingService = (ITracingService)serviceProvider.GetService(typeof(ITracingService));
if (tracingService == null)
throw new InvalidPluginExecutionException("Failed to retrieve the tracing service.");
IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
tracingService.Trace("Plugin has started..");
//l'expression de condition
ConditionExpression condition = new ConditionExpression("new_datenaissance", ConditionOperator.NotNull);
FilterExpression filter = new FilterExpression();
filter.Conditions.Add(condition);
ColumnSet cols = new ColumnSet();
//cols.AddColumn("Id");
cols.AddColumn("new_candidatid");
cols.AddColumn("new_age");
cols.AddColumn("new_datenaissance");
QueryExpression query = new QueryExpression();
query.Criteria = filter;
query.EntityName = "new_candidat";
query.ColumnSet = cols;
tracingService.Trace("appel retrieve multiple with date=" + DateTime.Now.ToString() + "/"+DateTime.Now.ToLocalTime().ToString());
var retrieve = service.RetrieveMultiple(query).Entities;
foreach (var c in retrieve)
{
var dt =(DateTime)c.Attributes["new_datenaissance"];
tracingService.Trace(dt.ToString());
if (dt.Month == DateTime.Now.Month && dt.Day == DateTime.Now.Day)
{
tracingService.Trace((DateTime.Now.Year - DateTime.Parse(c["new_datenaissance"].ToString()).Year).ToString());
c.Attributes["new_age"] = DateTime.Now.Year - DateTime.Parse(c["new_datenaissance"].ToString()).Year;
tracingService.Trace(c.Attributes["new_candidatid"].ToString() +" - "+c.Attributes["new_age"].ToString());
service.Update(c);
tracingService.Trace("updated");
}
}
tracingService.Trace("Plugin done working");
throw new InvalidPluginExecutionException("This is from a plugin that Mehdi has created ");
}
catch (Exception exc)
{
throw exc;
}
}
}
}

Answer 1

Whenever you throw an exception within a plugin the transaction is aborted so you won't see your changes applied. Remove the following line:
throw new InvalidPluginExecutionException("This is from a plugin that Mehdi has created ");
I assume you added this to see the trace output which is only available when an exception is thrown. With CRM Online your best bet for tracing is to write to a custom trace entity.