How do I retrieve the Event Definition in a Custom Journey Builder Activity?

Question

I have a custom Journey Builder activity. What I would like to do, is display a list of fields present in the Entry data source when the user is configuring the activity.

To do this, I have assumed that during the initActivity trigger from Postmonger I would:

1. Request Endpoints
2. Request Tokens
3. Request Trigger Event Definition

This would then give me the Event Key, Endpoints, and tokens. I assume then that I can use the /interaction/v1/events REST route https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-apis.meta/mc-apis/postEvent.htm to retrieve a list of data fields in the Event DE.

My code for this:

connection.on('requestedEndpoints',function(endPoints){
    
    console.log("****** ENDPOINTS ******");
    
    connection.on('requestedTriggerEventDefinition',function(eventTrigger){
        
        console.log("****** EVENT ******");
        
        connection.on('requestedTokens',function(tokens){
            
            console.log("************ REQUESTED TOKENS NESTED ****************");
            console.log(endPoints);
            console.log(eventTrigger);
            console.log(tokens);
            
            $.ajax({
                url:endPoints.fuelapiRestHost + 'interaction/v1/eventDefinitions/Key:' + eventTrigger.eventDefinitionKey,
                method:'GET',
                headers:{Authorization:'Bearer ' + tokens.token},
                success:function(data,textStatus,jqXHR){
                    console.log("******************** EVENT REQUEST RESULT ******************");
                    console.log(data);
                }
            });
            
        });
        
        connection.trigger('requestTokens');
    });
    
    connection.trigger('requestTriggerEventDefinition');
});

Obviously though, because this is done on the front-end, I'm getting CORS policy errors.

But; I don't see any routes documented that would be called prior: https://developer.salesforce.com/docs/atlas.en-us.noversion.mc-app-development.meta/mc-app-development/custom-activity-config.htm to allow me to prepare the event fields ahead of time.

Does anyone know how I can accomplish this.

Answer 1

You can request the event definition key using the trigger that you have listed above (with some simple modifications). This will get the event definition key and set as a variable that you can use to pass in your payload to the back-end. To generate your tokens, just decode the JWT and parse out your token from there.

  connection.on("requestedTriggerEventDefinition", function (
    eventDefinitionModel
  ) {
    if (eventDefinitionModel) {
      definition = eventDefinitionModel;
      eventDefinitionKey = eventDefinitionModel.eventDefinitionKey;
    }
  });