Add Kafka options to support custom header to add offset and partition into CapHeader. #374

src/DotNetCore.CAP.Kafka/CAP.KafkaOptions.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Linq;
+using Confluent.Kafka;
 
 // ReSharper disable once CheckNamespace
 namespace DotNetCore.CAP
@@ -43,6 +44,11 @@ namespace DotNetCore.CAP
         /// </summary>
         public string Servers { get; set; }
 
+        /// <summary>
+        /// If you need to get offset and partition and so on.., you can use this function to write additional header into <see cref="CapHeader"/>
+        /// </summary>
+        public Func<ConsumeResult<string, byte[]>, List<KeyValuePair<string, string>>> CustomHeaders { get; set; }
+
         internal IEnumerable<KeyValuePair<string, string>> AsKafkaConfig()
         {
             if (_kafkaConfig == null)

src/DotNetCore.CAP.Kafka/KafkaConsumerClient.cs

@@ -62,6 +62,15 @@ namespace DotNetCore.CAP.Kafka
                 }
                 headers.Add(Messages.Headers.Group, _groupId);
 
+                if (_kafkaOptions.CustomHeaders != null)
+                {
+                    var customHeaders = _kafkaOptions.CustomHeaders(consumerResult);
+                    foreach (var customHeader in customHeaders)
+                    {
+                        headers.Add(customHeader.Key, customHeader.Value);
+                    }
+                }
+
                 var message = new TransportMessage(headers, consumerResult.Value);
 
                 OnMessageReceived?.Invoke(consumerResult, message);