feat: custom platform event template

Author: pozil

src/main/default/classes/StreamingMonitorController.cls

@@ -32,6 +32,21 @@ public abstract class StreamingMonitorController {
         'UriEventStream'
     };
 
+    private final static List<String> PLATFORM_EVENT_STANDARD_FIELDS = new List<String>{
+        'replayid',
+        'createddate',
+        'createdbyid',
+        'eventuuid'
+    };
+
+    private final static Map<Schema.SOAPType, Object> DEFAULT_FIELD_VALUES = new Map<Schema.SOAPType, Object>{
+        Schema.SOAPType.STRING => '',
+        Schema.SOAPType.DATE => '2025-01-01',
+        Schema.SOAPType.DATETIME => '2025-01-01T00:00:00Z',
+        Schema.SOAPType.BOOLEAN => false,
+        Schema.SOAPType.DOUBLE => 0
+    };
+
     @AuraEnabled
     public static void publishStreamingEvent(
         String eventType,
@@ -85,6 +100,31 @@ public abstract class StreamingMonitorController {
         ];
     }
 
+    @AuraEnabled
+    public static Map<String, Object> getBlankPlatformEvent(String eventName) {
+        // Get object fields
+        Schema.DescribeSobjectResult[] results;
+        try {
+            results = Schema.describeSObjects(new List<String>{ eventName });
+        } catch (Exception e) {
+            throw new StreamingException(
+                'Unknown platform event type: ' + eventName
+            );
+        }
+        Map<String, Schema.SObjectField> fields = results[0].fields.getMap();
+        // Remove standard fields
+        Set<String> fieldNames = fields.keySet();
+        fieldNames.removeAll(PLATFORM_EVENT_STANDARD_FIELDS);
+        Map<String, Object> event = new Map<String, Object>();
+        // Add default values for fields
+        for (String fieldName : fieldNames) {
+            Schema.DescribeFieldResult dfr = fields.get(fieldName)
+                .getDescribe();
+            event.put(fieldName, DEFAULT_FIELD_VALUES.get(dfr.getSOAPType()));
+        }
+        return event;
+    }
+
     private static void publishPlatformEvent(
         String eventName,
         String eventPayload

src/main/default/lwc/actions/actions.js

@@ -14,6 +14,8 @@ import {
     getChannelPrefix
 } from 'c/streamingUtility';
 
+import getBlankPlatformEvent from '@salesforce/apex/StreamingMonitorController.getBlankPlatformEvent';
+
 import subscribeAll from './subscribeAll.html';
 import subscribe from './subscribe.html';
 import publish from './publish.html';
@@ -130,10 +132,21 @@ export default class Actions extends LightningElement {
         this.pubPayload = undefined;
     }
 
-    handlePubEventNameChange(event) {
+    async handlePubEventNameChange(event) {
         this.pubEventName = event.detail.value;
         this.pubChannel =
             getChannelPrefix(this.pubEventType) + this.pubEventName;
+        // Load blank event for platform event
+        if (this.pubEventType === EVT_PLATFORM_EVENT) {
+            try {
+                const blankEvent = await getBlankPlatformEvent({
+                    eventName: this.pubEventName
+                });
+                this.pubPayload = JSON.stringify(blankEvent, null, 2);
+            } catch (error) {
+                console.error(error);
+            }
+        }
     }
 
     handlePubPayloadChange(event) {