System.NullReferenceException: Object not set to an instance of an object? - dynamics-crm

Question

I am writing a plugin that deletes records between two dates when a contract is cancelled... The records to be deleted are from the cancellation date to the end of the contract. Here is the code I am using:
using System;
using System.Linq;
using System.ServiceModel;
using Microsoft.Xrm.Sdk;
using Microsoft.Xrm.Sdk.Messages;
using Microsoft.Xrm.Sdk.Query;
/// <summary>
/// This plugin will trimm off unit orders after a contract is cancelled before the end of the contract duration
/// </summary>
namespace DCWIMS.Plugins
{
[CrmPluginRegistration(MessageNameEnum.Update,
"contract",
StageEnum.PostOperation,
ExecutionModeEnum.Asynchronous,
"statecode",
"Post-Update On Cancel Contract",
1000,
IsolationModeEnum.Sandbox,
Image1Name = "PreImage",
Image1Type = ImageTypeEnum.PreImage,
Image1Attributes = "")]
public class UnitPluginOnCancel : IPlugin
{
public void Execute(IServiceProvider serviceProvider)
{
// Extract the tracing service for use in debugging sandboxed plug-ins.
// Will be registering this plugin, thus will need to add tracing service related code.
ITracingService tracing = (ITracingService)serviceProvider.GetService(typeof(ITracingService));
//obtain execution context from service provider.
IPluginExecutionContext context = (IPluginExecutionContext)
serviceProvider.GetService(typeof(IPluginExecutionContext));
// InputParameters collection contains all the data passed in the message request.
if (context.InputParameters.Contains("Target") &&
context.InputParameters["Target"] is Entity)
{
Entity entity = (Entity)context.InputParameters["Target"];
//Get the before image of the updated contract
Entity PreImage = context.PreEntityImages["PreImage"];
//verify that the target entity represents the the contract entity has been cancelled
if (entity.LogicalName != "contract" || entity.GetAttributeValue<OptionSetValue>("statecode").Value != 4)
return;
//obtain the organization service for web service calls.
IOrganizationServiceFactory serviceFactory =
(IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
IOrganizationService service = serviceFactory.CreateOrganizationService(context.UserId);
//Core Plugin code in Try Block
try
{
//Get Contract line start date
var startDate = entity.GetAttributeValue<DateTime>("cancelon");
//Get Contract Line End Date
DateTime endDate = (DateTime)PreImage["expireson"];
//Get Contract range into weekdays list
Eachday range = new Eachday();
var weekdays = range.WeekDay(startDate, endDate);
//Get Unit Order Lookup Id
EntityReference unitOrder = (EntityReference)PreImage.Attributes["new_unitorderid"];
var unitOrderId = unitOrder.Id;
var unitOrders = service.Retrieve(unitOrder.LogicalName, unitOrder.Id, new ColumnSet("new_name"));
var uiName = unitOrders.GetAttributeValue<string>("new_name");
//Get Entity Collection to delete
string fetchXml = #" <fetch version='1.0' output-format='xml-platform' mapping='logical' distinct='false' top='2000'>
<entity name='new_units'>
<link-entity name='new_alterunitorder' from ='new_orderlineid' to = 'new_unitsid' >
<attribute name='new_alterunitorderid' />
<filter type='and'>
<condition attribute='new_orderdate' operator='on-or-after' value='" + startDate.ToShortDateString() + #"' />
<condition attribute='new_orderdate' operator='on-or-before' value='" + endDate.ToShortDateString() + #"' />
<condition attribute='new_orderlineid' operator='eq' uiname='" + uiName + #"' uitype='new_units' value='" + unitOrderId + #"' />
</filter>
</link-entity>
</entity>
</fetch>";
var result = service.RetrieveMultiple(new FetchExpression(fetchXml));
var entityRefs = result.Entities.Select(e => e.GetAttributeValue<EntityReference>("new_alterunitorderid"));
var batchSize = 1000;
var batchNum = 0;
var numDeleted = 0;
while (numDeleted < entityRefs.Count())
{
var multiReq = new ExecuteMultipleRequest()
{
Settings = new ExecuteMultipleSettings()
{
ContinueOnError = false,
ReturnResponses = false
},
Requests = new OrganizationRequestCollection()
};
var currentList = entityRefs.Skip(batchSize * batchNum).Take(batchSize).ToList();
currentList.ForEach(r => multiReq.Requests.Add(new DeleteRequest { Target = r }));
service.Execute(multiReq);
numDeleted += currentList.Count;
batchNum++;
}
}
catch (FaultException<OrganizationServiceFault> ex)
{
throw new InvalidPluginExecutionException("An error occured.. Phil is responsible. ", ex);
}
catch (Exception ex)
{
tracing.Trace("An error occured: {0}", ex.ToString());
throw;
}
}
}
}
}
I am getting a NullReferenceException on line 55... I have literally used the same line for a previous plugin without any problems.. The statecode for a cancelled contract has a value of 4 and I only want the plugin to execute when the contract has been cancelled. Here is an image of the debugging.
I have used this statement before for another plugin that acts on the contract entity and it worked fine, I don't know why this time it's not working. Here is the statement:
//verify that the target entity represents the the contract entity has been cancelled
if (entity.LogicalName != "contract" || entity.GetAttributeValue<OptionSetValue>("statecode").Value != 4)
return;

Answer 1

The entity you get from the input parameters may not have StateCode in it, so .Value is failing.
Maybe try entity.GetAttributeValue<OptionSetValue>("statecode") or entity.Contains("statecode") to see if there's anything there before you dereference .Value.
Since you have the PreImage, you may want to look there for the statecode.

Answer 2

Check to see if you are using the right profile while debugging... If you are using the wrong profile, a null reference will through on a method when it shouldn't!
Hope that helps!