Adding Remote Event Receivers To An Exisiting List In Office 365

// This Below method is used to build creation information for the event receiver.

public static EventReceiverDefinitionCreationInformation CreateGenericEventRecieverWithoutEventType()
{
string remoteAppurl = HttpContext.Current.Request["RemoteAppUrl"];
string remoteEventEndPointUrl = String.Format("{0}/ServiceName.svc", remoteAppurl);
EventReceiverDefinitionCreationInformation eventReceiver = new EventReceiverDefinitionCreationInformation();
eventReceiver.ReceiverName = "Give Your Receiver Name";
eventReceiver.ReceiverUrl = remoteEventEndPointUrl;
eventReceiver.SequenceNumber = 5000;
eventReceiver.ReceiverClass = "Fully qualified Path To RER Assembly";
eventReceiver.ReceiverAssembly = Assembly.GetExecutingAssembly().FullName;
return eventReceiver;
}

// The below method is used to check whether the event receiver is already exists in the lists or not

public static bool DoesEventReceiverDefintionExistBasedOnCreationInfo(EventReceiverDefinitionCreationInformation info, List list)
{
bool exists = false;
list.Context.Load(list, x => x.EventReceivers);
list.Context.ExecuteQuery();
foreach (EventReceiverDefinition eventReceiverDefinition in list.EventReceivers)
{
string innerDefId = eventReceiverDefinition.ReceiverClass;
string outerDefId = info.ReceiverClass;
if (innerDefId.Equals(outerDefId, StringComparison.InvariantCultureIgnoreCase))
{
exists = true;
break;
}
}
return exists;
}

// Since the receivers were built without a specific event type, you can specify as many receiver capture behaviors as you want, as demonstrated in the below example.

public static void AttachEventReceiver(ClientContext context, List list)
{
EventReceiverDefinitionCreationInformation eventReceiver =CreateGenericEventRecieverWithoutEventType();
eventReceiver.EventType = EventReceiverType.ItemAdded;
if (!DoesEventReceiverDefintionExistBasedOnCreationInfo(eventReceiver, list))
{
list.EventReceivers.Add(eventReceiver);
}
eventReceiver = CreateGenericEventRecieverWithoutEventType();
eventReceiver.EventType = EventReceiverType.ItemUpdated;
if (!DoesEventReceiverDefintionExistBasedOnCreationInfo(eventReceiver, list))
{
list.EventReceivers.Add(eventReceiver);
}
eventReceiver = CreateGenericEventRecieverWithoutEventType();
eventReceiver.EventType = EventReceiverType.ItemDeleted;
if (!DoesEventReceiverDefintionExistBasedOnCreationInfo(eventReceiver, list))
{
list.EventReceivers.Add(eventReceiver);
}
eventReceiver = CreateGenericEventRecieverWithoutEventType();
eventReceiver.EventType = EventReceiverType.ItemFileMoved;
if (!DoesEventReceiverDefintionExistBasedOnCreationInfo(eventReceiver, list))
{
list.EventReceivers.Add(eventReceiver);
}
context.ExecuteQuery();
}

//The below method is used to delete event receivers in the list 

public static void DeleteEventReceiver(ClientContext context, List list)
{
EventReceiverDefinitionCollection eventReceiverDefinitionCollection = list.EventReceivers;
context.Load(eventReceiverDefinitionCollection);
context.ExecuteQuery();
List<Guid> ids = eventReceiverDefinitionCollection.Select(eventReceiverDefinition => eventReceiverDefinition.ReceiverId).ToList();
foreach (EventReceiverDefinition definition in ids.Select(eventReceiverDefinitionCollection.GetById))
{
definition.DeleteObject();
context.ExecuteQuery();
}
}