CRM 2011 - Given key was not present in dictionary - Update contact plugin - plugins

Question

I'm trying to bind a plugin to the update contact event in Microsoft Dynamics CRM 2011.
I've made a plugin and i already registered the assembly and step for my organisation.
screenshot: CRM registration tool
For this moment, i'm using sample code for my plugin.
public class Plugin : IPlugin
{
public void Execute(IServiceProvider serviceProvider)
{
IPluginExecutionContext context = (IPluginExecutionContext)
serviceProvider.GetService(typeof(IPluginExecutionContext));
Entity entity;
// Check if the input parameters property bag contains a target
// of the create operation and that target is of type Entity.
if (context.InputParameters.Contains("Target") &&
context.InputParameters["Target"] is Entity)
{
// Obtain the target business entity from the input parameters.
entity = (Entity)context.InputParameters["Target"];
// Verify that the entity represents a contact.
if (entity.LogicalName != "contact") { return; }
}
else
{
return;
}
try
{
IOrganizationServiceFactory serviceFactory =
(IOrganizationServiceFactory)serviceProvider.GetService(
typeof(IOrganizationServiceFactory));
IOrganizationService service =
serviceFactory.CreateOrganizationService(context.UserId);
var id = (Guid)context.OutputParameters["id"];
AddNoteToContact(service, id);
}
catch (FaultException<OrganizationServiceFault> ex)
{
throw new InvalidPluginExecutionException(
"An error occurred in the plug-in.", ex);
}
}
private static void AddNoteToContact(IOrganizationService service, Guid id)
{
using (var crm = new XrmServiceContext(service))
{
var contact = crm.ContactSet.Where(
c => c.ContactId == id).First();
Debug.Write(contact.FirstName);
var note = new Annotation
{
Subject = "Created with plugin",
NoteText = "This Note was created by the example plug-in",
ObjectId = contact.ToEntityReference(),
ObjectTypeCode = contact.LogicalName
};
crm.AddObject(note);
crm.SaveChanges();
}
}
}
But every time i modify a contact form and save it, i get this error:
The given key was not present in the dictionary
I've been looking for answers for a week now. I hope there is someone here who can guide me to the sollution for this problem. I can give every code or information you need. But for now, i can't think of anything more that maybe can help you to see where my error is located. Any help is very much appreciated.
Thanks!

Answer 1

If the plugin is registered as a pre step, OutputParameters will not contain the key "id" and it will throw that error.

Answer 2

M.Medhat is absolutely correct, but let's expand on it a bit more so you understand.
The first thing that you need to know is the difference between InputParameters vrs OutputParameters. A quick read at this MSDN article describing the difference between InputParameters and OutputParameters.
Make sure to note this statement:
If a plug-in is registered for a pre-event, the OutputParameters property bag would not contain a value for the "id" key because the core operation would not yet have occurred.
Hence, this code would break:
var id = (Guid)context.OutputParameters["id"];
Since you've already created an entity (by casting it off of InputParameters) you could delete that line and do something like this:
AddNoteToContact(service, entity.id);
Don't forget about tracing, it's your best friend. It can show information when an exception is thrown. Here's a good link on it: tracing

Answer 3

Here is some code I use to help show all the parameters the plugin receives when registered for a given message and target entity, use it to find out what keys are present.
If you are less inclined to dig through documentation to see what "should" be there, than to just try and see what actually happens, simply put this in your plugin, register the step you intend to use and it will show you exactly what params were provided for that step.
var propertiesList = String.Join("\n",
context.InputParameters.Select((p,i)=>ParamSelector(p,i,"Input")).Union(
context.InputParameters.Select((p,i)=>ParamSelector(p,i,"Output"))));
//send the list to the tracing service.
context.Trace("Listing Inputput and Output Parameters for the plugin.\n" + propertiesList);
// throw an exception to see the trace values pop-up (in a synchronous plugin).
throw new InvalidPluginExecutionException("Check the trace for a listing of parameters.");
supporting delegates for formatting:
private string ParamSelector(KeyValuePair<string, object> p, int index, string inOut)
{
return String.Format("{2} \tKey:'{0}'\tValue:{1}\n{3}", p.Key, p.Value, inOut, EntityToTraceStrings(p.Value as Entity));
}
private string EntityToTraceStrings(Entity entity)
{
return entity == null ? String.Empty : String.Concat(
String.Format("- Entity: {0} Id: {1}\n\t", entity.LogicalName, entity.Id),
String.Join("\n\t", entity.FormattedValues.Select((p, j) => String.Format("Attribute: {0} \t Value: {1}", p.Key, p.Value))));
}