create remote event receiver without handling app installed

Question

How to deploy a remote event receiver without handling the app installed, I know that this can be done with powershell but I already tried it, the RER is reflecting in the list, but the program itself is not working, should I edit something in my solution for this to work?

$receiverName = "ItemDeletingRER"
$receiverClassName = "ItemDeletingRER"
$receiverUrl = "https://pbpotest.azurewebsites.net/Services/ItemDeletingRER.svc"
$receiverAssemblyName = "ResourceListRERWeb, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"

$newRER = New-Object Microsoft.SharePoint.Client.EventReceiverDefinitionCreationInformation
$newRER.EventType = [Microsoft.SharePoint.Client.EventReceiverType]::ItemDeleting
$newRER.ReceiverName = $receiverName
$newRER.ReceiverClass = $receiverClassName
$newRER.ReceiverAssembly = $receiverAssemblyName
$newRER.ReceiverUrl = $receiverUrl
$newRER.SequenceNumber = 15001
$newRER.Synchronization = [Microsoft.SharePoint.Client.EventReceiverSynchronization]::Synchronous

what my event receiver do is that it prevents an item from being deleted if the value of a column is "yes", thats the part that is not working.

Here is a snippet of my event receiver:

public SPRemoteEventResult ProcessEvent(SPRemoteEventProperties properties)
{
    using (ClientContext clientContext = TokenHelper.CreateRemoteEventReceiverClientContext(properties))
    {
        SPRemoteEventResult result = new SPRemoteEventResult();

        if (properties.EventType == SPRemoteEventType.ItemDeleting)
        {
            List list = clientContext.Web.Lists.GetByTitle(properties.ItemEventProperties.ListTitle);
            ListItem fieldItem = list.GetItemById(properties.ItemEventProperties.ListItemId);

            clientContext.Load(fieldItem);
            clientContext.ExecuteQuery();

            if ((bool)fieldItem["Promoted_x0020_To_x0020_Resource_x003f_"])
            {
                result.Status = SPRemoteEventServiceStatus.CancelWithError;
                result.ErrorMessage = "Unable to delete document as it is currently used as a Resource. Please de-promote prior to deleting.";
            }
            else
            {
                result.Status = SPRemoteEventServiceStatus.Continue;
            }
        }

        return result;
    }
}

---

$username = "[email protected]"
$password = Read-Host -Prompt "Enter password" -AsSecureString 

$ctx = New-Object Microsoft.SharePoint.Client.ClientContext($siteURL)
#$context = New-Object Microsoft.SharePoint.Client.ClientContext($siteURL2)

$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($username, $password) 
$ctx.Credentials = $credentials

Answer 1

Thank for providing the full picture.

You definitely can create an event receiver outside AppInstalled, however will your RER code work or not will depend heavily on the way you added those event receivers and your actual RER code.

In your code you use TokenHelper.CreateRemoteEventReceiverClientContext(properties). This code expects, that properties contains something called context object (properties.ContextToken). If you have created your RER with PowerShell with your user credentials, ContextToken will be always null. In other words, your context knows nothing about your add-in (client id and client secret) That's why it doesn't work in your case.

To make it work, you should add RER using ClientContext created with help of your add-in credentials (ClientId, ClientSecret). I haven't found corresponding PS code, you can use .net console appliaction.
You should create new console project in VS, add PnP Core nuget package.

Then your code will be:

AuthenticationManager authManager = new AuthenticationManager();  
ClientContext context = authManager.GetAppOnlyAuthenticatedContext(siteUrl, clientId, clientSecret);


EventReceiverDefinitionCreationInformation eventReceiver = new EventReceiverDefinitionCreationInformation();
eventReceiver.EventType = EventReceiverType.ItemAdding;
eventReceiver.ReceiverAssembly = Assembly.GetExecutingAssembly().FullName;
eventReceiver.ReceiverClass = "HTools_EventReceiver";
eventReceiver.ReceiverName = "HTools_EventReceiver";
eventReceiver.ReceiverUrl = "http://hh-wks-robb:2145/HTools_EventReceiver.svc";
eventReceiver.SequenceNumber = 1000;

List targetList = context.web.Lists.GetByTitle("your list");
targetList.EventReceivers.Add(eventReceiver);

context.ExecuteQuery();

You should use the same ClientId and Secret you used when creating your app.