Add JsConfig.MaxDepth feature to prevent cyclical dependencies. fixes #331

Author: mythz

src/ServiceStack.Text/Common/JsState.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace ServiceStack.Text.Common
 {
@@ -16,5 +17,8 @@ internal static class JsState
 
         [ThreadStatic]
         internal static bool QueryStringMode = false;
+
+        [ThreadStatic]
+        internal static int Depth = 0;
     }
 }

src/ServiceStack.Text/JsConfig.cs

@@ -47,6 +47,7 @@ public static JsConfigScope With(
             bool? alwaysUseUtc = null,
             bool? escapeUnicode = null,
             bool? includePublicFields = null,
+            int? maxDepth = null,
             EmptyCtorFactoryDelegate modelFactory = null)
         {
             return new JsConfigScope {
@@ -68,6 +69,7 @@ public static JsConfigScope With(
                 AlwaysUseUtc = alwaysUseUtc ?? sAlwaysUseUtc,
                 EscapeUnicode = escapeUnicode ?? sEscapeUnicode,
                 IncludePublicFields = includePublicFields ?? sIncludePublicFields,
+                MaxDepth = maxDepth ?? sMaxDepth,
                 ModelFactory = modelFactory ?? ModelFactory,
             };
         }
@@ -445,6 +447,24 @@ public static bool IncludePublicFields
             }
         }
 
+        /// <summary>
+        /// Sets the maximum depth to avoid circular dependencies
+        /// </summary>
+        private static int? sMaxDepth;
+        public static int MaxDepth
+        {
+            get
+            {
+                return (JsConfigScope.Current != null ? JsConfigScope.Current.MaxDepth : null)
+                    ?? sMaxDepth
+                    ?? int.MaxValue;
+            }
+            set
+            {
+                if (!sMaxDepth.HasValue) sMaxDepth = value;
+            }
+        }
+
         /// <summary>
         /// Set this to enable your own type construction provider.
         /// This is helpful for integration with IoC containers where you need to call the container constructor.

src/ServiceStack.Text/JsConfigScope.cs

@@ -75,6 +75,7 @@ public void Dispose()
         public bool? EscapeUnicode { get; set; }
         public bool? PreferInterfaces { get; set; }
         public bool? IncludePublicFields { get; set; }
+        public int? MaxDepth { get; set; }
         public EmptyCtorFactoryDelegate ModelFactory { get; set; }
     }
 }

src/ServiceStack.Text/Json/JsonWriter.Generic.cs

@@ -172,13 +172,32 @@ static JsonWriter()
                 : JsonWriter.Instance.GetWriteFn<T>();
 		}
 
-	    public static void WriteObject(TextWriter writer, object value)
-		{
+        public static void WriteObject(TextWriter writer, object value)
+        {
 #if MONOTOUCH
 			if (writer == null) return;
 #endif
-			CacheFn(writer, value);
-		}
-	}
+            try
+            {
+                if (++JsState.Depth > JsConfig.MaxDepth)
+                    return;
+
+                CacheFn(writer, value);
+            }
+            finally
+            {
+                JsState.Depth--;
+            }
+        }
+
+        public static void WriteRootObject(TextWriter writer, object value)
+        {
+#if MONOTOUCH
+			if (writer == null) return;
+#endif
+            JsState.Depth = 0;
+            CacheFn(writer, value);
+        }
+    }
 
 }

src/ServiceStack.Text/JsonSerializer.cs

@@ -72,7 +72,7 @@ public static string SerializeToString<T>(T value)
 				}
 				else
 				{
-					JsonWriter<T>.WriteObject(writer, value);
+					JsonWriter<T>.WriteRootObject(writer, value);
 				}
 			}
 			return sb.ToString();
@@ -113,7 +113,7 @@ public static void SerializeToWriter<T>(T value, TextWriter writer)
                 return;
             }
 
-			JsonWriter<T>.WriteObject(writer, value);
+			JsonWriter<T>.WriteRootObject(writer, value);
 		}
 
 		public static void SerializeToWriter(object value, Type type, TextWriter writer)
@@ -140,7 +140,7 @@ public static void SerializeToStream<T>(T value, Stream stream)
             }
 
 			var writer = new StreamWriter(stream, UTF8EncodingWithoutBom);
-			JsonWriter<T>.WriteObject(writer, value);
+			JsonWriter<T>.WriteRootObject(writer, value);
 			writer.Flush();
 		}
 

src/ServiceStack.Text/Jsv/JsvWriter.Generic.cs

@@ -120,13 +120,32 @@ static JsvWriter()
                 : JsvWriter.Instance.GetWriteFn<T>();
 		}
 
-	    public static void WriteObject(TextWriter writer, object value)
-		{
+        public static void WriteObject(TextWriter writer, object value)
+        {
 #if MONOTOUCH
 			if (writer == null) return;
 #endif
-			CacheFn(writer, value);
-		}
+            try
+            {
+                if (++JsState.Depth > JsConfig.MaxDepth)
+                    return;
 
-	}
+                CacheFn(writer, value);
+            }
+            finally 
+            {
+                JsState.Depth--;
+            }
+        }
+
+        public static void WriteRootObject(TextWriter writer, object value)
+        {
+#if MONOTOUCH
+			if (writer == null) return;
+#endif
+            JsState.Depth = 0;
+            CacheFn(writer, value);
+        }
+
+    }
 }

src/ServiceStack.Text/TypeSerializer.cs

@@ -91,7 +91,7 @@ public static string SerializeToString<T>(T value)
 			var sb = new StringBuilder();
 			using (var writer = new StringWriter(sb, CultureInfo.InvariantCulture))
 			{
-				JsvWriter<T>.WriteObject(writer, value);
+                JsvWriter<T>.WriteRootObject(writer, value);
 			}
 			return sb.ToString();
 		}
@@ -125,7 +125,7 @@ public static void SerializeToWriter<T>(T value, TextWriter writer)
                 return;
 			}
 
-			JsvWriter<T>.WriteObject(writer, value);
+            JsvWriter<T>.WriteRootObject(writer, value);
 		}
 
 		public static void SerializeToWriter(object value, Type type, TextWriter writer)
@@ -152,7 +152,7 @@ public static void SerializeToStream<T>(T value, Stream stream)
 			}
 
 			var writer = new StreamWriter(stream, UTF8EncodingWithoutBom);
-			JsvWriter<T>.WriteObject(writer, value);
+            JsvWriter<T>.WriteRootObject(writer, value);
 			writer.Flush();
 		}
 

tests/ServiceStack.Text.Tests/CyclicalDependencyTests.cs

@@ -152,5 +152,26 @@ public void Can_serialize_Error()
 			Assert.That(from.Contact, Is.EqualTo(dto.Contact));
 			Assert.That(from.Notes, Is.EqualTo(dto.Notes));
 		}
+
+        class person
+        {
+            public string name { get; set; }
+            public person teacher { get; set; }
+        }
+
+	    [Test]
+	    public void Can_limit_cyclical_dependencies()
+	    {
+	        using (JsConfig.With(maxDepth:4))
+	        {
+                var p = new person();
+                p.teacher = new person { name = "sam", teacher = p };
+                p.name = "bob";
+                p.ToJsv().Print();
+                p.ToJson().Print();
+            }
+        }
+
+
 	}
 }