Update Watchlist of any Table based on payload

Server-Side Components/Script Includes/UpdateWatchlistFromJSON/README.md

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+UseCase - 
+
+Update the watchlist of any table record with the provided JSON payload which should maintain the previous watchlist user and add new one from the payload
+
+Payload can be Array, String, List of String
+
+//Passing List of String of SysId of users
+var payload = '43435efdsre4t5953439434,43434343436fdfsd343,frtgr6565hg676767gt';
+updateWatchlistFromJSON('incident','a1b2c3d4e5f678901234567890abcdef', payload);
+
+//Passing Array of String of SysId of users
+var payload = '[43435efdsre4t5953439434,43434343436fdfsd343]';
+updateWatchlistFromJSON('incident','a1b2c3d4e5f678901234567890abcdef', payload);

Server-Side Components/Script Includes/UpdateWatchlistFromJSON/script.js

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+function updateWatchlistFromJSON(tableName, recordSysId, jsonPayload) {
+	// Check for valid 'watch_list' data
+    	if (jsonPayload) {
+        	gs.error("JSON must not be empty");
+        	return;
+    	}    
+        var data = JSON.parse(jsonPayload);
+	// Check if data is array else convert List of string to array
+	var newWatchers = Array.isArray(data) ? data : data.split(',');
+
+	// fetch the record by table name and record sys id
+    	var gr = new GlideRecord(tableName);
+    	if (gr.get(recordSysId)) {
+		// get the existing watchlist data
+        	var existingWatchlist = gr.watch_list ? gr.watch_list.split(',') : [];
+
+		// Add the new watchlist sys ids into exisitng watchlist
+        	for (var i = 0; i < newWatchers.length; i++) {
+            		var watcher = newWatchers[i];
+                	existingWatchlist.push(watcher);
+            	}
+
+        }
+	// Remove the duplicate by using SET 
+	var watcherSet = new Set(existingWatchlist);
+	// Update the newlist into watchlist
+        gr.watch_list = Array.from(watcherSet).join(',');
+        gr.update();
+
+        gs.info("Watchlist updated successfully for Table "+tableName+": " + gr.number);
+    } else {
+        gs.error("Record not found for Table "+tableName+": " + recordSysId);
+    }
+}