Fixing null in log entry when CorrelationIdHeaderEnricher

src/Serilog.Enrichers.CorrelationId.Tests/Enrichers/CorrelationIdEnricherTests.cs

@@ -57,5 +57,28 @@ public void When_CurrentHttpContextIsNotNull_ShouldNot_CreateCorrelationIdProper
             Assert.NotNull(evt);
             Assert.IsFalse(evt.Properties.ContainsKey("CorrelationId"));
         }
+
+        [Test]
+        public void When_MultipleLoggingCallsMade_Should_KeepUsingCreatedCorrelationIdProperty()
+        {
+            var httpContext = new DefaultHttpContext();
+
+            A.CallTo(() => _httpContextAccessor.HttpContext)
+                .Returns(httpContext);
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.With(_enricher)
+                .WriteTo.Sink(new DelegateSink.DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            log.Information(@"Has a CorrelationId property");
+
+            var correlationId = evt.Properties["CorrelationId"].LiteralValue();
+
+            log.Information(@"Here is another event");
+
+            Assert.AreEqual(correlationId, evt.Properties["CorrelationId"].LiteralValue());
+        }
     }
 }

src/Serilog.Enrichers.CorrelationId.Tests/Enrichers/CorrelationIdHeaderEnricherTests.cs

@@ -82,5 +82,28 @@ public void When_CurrentHttpContextIsNull_ShouldNot_CreateCorrelationIdProperty(
             Assert.NotNull(evt);
             Assert.IsFalse(evt.Properties.ContainsKey("CorrelationId"));
         }
+
+        [Test]
+        public void When_MultipleLoggingCallsMade_Should_KeepUsingCreatedCorrelationIdProperty()
+        {
+            var httpContext = new DefaultHttpContext();
+
+            A.CallTo(() => _httpContextAccessor.HttpContext)
+                .Returns(httpContext);
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.With(_enricher)
+                .WriteTo.Sink(new DelegateSink.DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            log.Information(@"Has a CorrelationId property");
+
+            var correlationId = evt.Properties["CorrelationId"].LiteralValue();
+
+            log.Information(@"Here is another event");
+
+            Assert.AreEqual(correlationId, evt.Properties["CorrelationId"].LiteralValue());
+        }
     }
 }

src/Serilog.Enrichers.CorrelationId/Enrichers/CorrelationIdHeaderEnricher.cs

@@ -37,7 +37,7 @@ public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
 
             var correlationIdProperty = new LogEventProperty(CorrelationIdPropertyName, new ScalarValue(correlationId));
 
-            logEvent.AddPropertyIfAbsent(correlationIdProperty);
+            logEvent.AddOrUpdateProperty(correlationIdProperty);
         }
 
         private string GetCorrelationId()
@@ -48,6 +48,10 @@ private string GetCorrelationId()
             {
                 header = values.FirstOrDefault();
             }
+            else if (_contextAccessor.HttpContext.Response.Headers.TryGetValue(_headerKey, out values))
+            {
+                header = values.FirstOrDefault();
+            }
 
             var correlationId = string.IsNullOrEmpty(header)
                                     ? Guid.NewGuid().ToString()