Plugin exception: Target not null but Object reference cannot be found

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Posted on by Joel D

355

Hello,

I created a plugin which is triggered when a user tries to deactivate an entity Movie; it should block the process if the movie is associated to an active entity of type Collection.

When I tried to deactivate some Movies the operation was always successful, no matter if they were related to an active Collection.

I'm debugging it and noticed that the current target is recognized, the following variable is not null:

var target = context.GetTarget();

Nonetheless, the following instruction throws the System.NullReferenceException:

Entity currentMovie = (Entity)context.InputParameters["Target"];

Can you please help me to understand why I get that exception and if the code is correct? I used if (collectionStateCode.Value == 0) to check if the state is active, is it correct?

Here is my code:

        public void Execute(IServiceProvider serviceProvider)
        {
            var context = new PluginContext(serviceProvider);
            var service = context.CrmServiceSystem;
            var trace = context.TracingService;
            var target = context.GetTarget();

            if (target == null)
                return;

            Entity currentMovie = (Entity)context.InputParameters["Target";

            // 2) Assuming that collection is a required field on the movie, get the collectionid
            Guid collectionid= currentMovie .GetAttributeValue<EntityReference>("collection").Id;

              // 3) Query the encyclopedia for the details I need:
            var collectionEntity = service.Retrieve("collection", collectionid, new ColumnSet("statecode"));

             // 4) get the values from the collection entity
            OptionSetValue collectionStateCode = (OptionSetValue)collectionEntity .Attributes["statecode";
            if (collectionStateCode.Value == 0)
            {
                throw new InvalidPluginExecutionException(OperationStatus.Failed,, "The movie cannot be disable because it is associated to an active collection.");
            }
        }

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Joel D 355 on at

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RE: Plugin exception: Target not null but Object reference cannot be found

Ok, it looks like the input parameters contain Target and target is an entity: I can go through the block of code inside the if statement, but the exception is thrown after the service declaration, it seems:
Prakash Kalimuthu on at

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RE: Plugin exception: Target not null but Object reference cannot be found

["Target"] is Entity.

Modify the code like mentioned above.
Joel D 355 on at

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RE: Plugin exception: Target not null but Object reference cannot be found

Thank you Prakash.

I added the condition under the context declaration but I got the following errors:
Prakash Kalimuthu on at

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RE: Plugin exception: Target not null but Object reference cannot be found

Hi Joel,

Code looks fine to me.

Can you check one condition, whether the target is entity or not and look for input parameters.

if(context.InputParameters.Contains("Target")&&

context.InputParameters["Target"]isEntity)

Regards,

Prakash
Joel D 355 on at

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RE: Plugin exception: Target not null but Object reference cannot be found

Hi Prakash,

thank you.

I followed your tip,I got a System.NullReferenceException, but now it was triggered before the declaration of the service, i.e. next to the following line of code:

.
var crmService = factory.CreateOrganizationService(context.UserId);

I also noticed that the context is not null but it shows the following errors:

This is the updated code:

IPluginExecutionContext context = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext)); IOrganizationServiceFactory factory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory)); var crmService = factory.CreateOrganizationService(context.UserId); Entity currentMovie = (Entity)context.InputParameters["Target"]; Guid collectionId = currentMovie.GetAttributeValue("collectionId").Id; var collectionEntity = crmService.Retrieve("collectionId", collectionId, new ColumnSet("statecode")); OptionSetValue collectionStateCode = (OptionSetValue)collectionEntity.Attributes["statecode"]; if (collectionStateCode.Value == 0) { throw new InvalidPluginExecutionException(OperationStatus.Failed, "The movie cannot be disable because it is associated to an active collection."); }
Prakash Kalimuthu on at

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RE: Plugin exception: Target not null but Object reference cannot be found

Hi Joel,

Can you please create context object using this way.

IPluginExecutionContext context =(IPluginExecutionContext) serviceProvider.GetService(typeof(IPluginExecutionContext));

It looks like something wrong with context object.

Regards,
Prakash