-Changed serializer to fallback to use a private default constructor

-Changed error message when deserializing a JSON object/array onto the wrong kind of type to be more descriptive

10 files changed, 71 insertions, 34 deletions

diff --git a/Doc/SerializationSettings.html b/Doc/SerializationSettings.html
index 21a51c2..d11a80f 100644
--- a/Doc/SerializationSettings.html
+++ b/Doc/SerializationSettings.html
@@ -405,10 +405,11 @@ DefaultValueHandling controls how Json.NET uses default values set using the .NE
             <div class="summary">

              By default Json.NET will first look for a constructor 

                 marked with the JsonConstructorAttribute, then look for a public default 

-                constructor (a constructor that doesn't take any arguments) and finally check if 

-                the class has a single public constructor with arguments. If the class has 

-                multiple public constructors with arguments an error will be thrown. This can be 

-                fixed by marking one of the constructors with the JsonConstructorAttribute.

+                constructor (a constructor that doesn't take any arguments), then check if 

+                the class has a single public constructor with arguments and finally check

+                for a non-public default constructor. If the class has multiple public

+                constructors with arguments an error will be thrown. This can be fixed by

+                marking one of the constructors with the JsonConstructorAttribute.

             </div>

             <br>

           </td>

@@ -419,8 +420,8 @@ DefaultValueHandling controls how Json.NET uses default values set using the .NE
           </td>

           <td>

             <div class="summary">

-             Json.NET will fallback to 

-                using a classes private default constructor if available.

+             Json.NET will use a classes private default constructor before constructors

+             with arguments if available.

             </div>

             <br>

           </td>

diff --git a/Src/Newtonsoft.Json.Tests/PerformanceTests.cs b/Src/Newtonsoft.Json.Tests/PerformanceTests.cs
index 7d3b8bd..268fe13 100644
--- a/Src/Newtonsoft.Json.Tests/PerformanceTests.cs
+++ b/Src/Newtonsoft.Json.Tests/PerformanceTests.cs
@@ -704,21 +704,6 @@ namespace Newtonsoft.Json.Tests
     }

 

     [Test]

-    public void RecursiveLoop()

-    {

-      JArray a1 = new JArray();

-      JArray a2 = new JArray();

-      JArray a3 = new JArray();

-      JArray a4 = new JArray();

-

-      a1.Add(a2);

-      a2.Add(a3);

-      a3.Add(a4);

-

-

-    }

-

-    [Test]

     public void NestedJToken()

     {

       Stopwatch sw;

diff --git a/Src/Newtonsoft.Json.Tests/Properties/AssemblyInfo.cs b/Src/Newtonsoft.Json.Tests/Properties/AssemblyInfo.cs
index 7920d37..1646871 100644
--- a/Src/Newtonsoft.Json.Tests/Properties/AssemblyInfo.cs
+++ b/Src/Newtonsoft.Json.Tests/Properties/AssemblyInfo.cs
@@ -72,5 +72,5 @@ using System.Security;
 // by using the '*' as shown below:

 [assembly: AssemblyVersion("4.0.8.0")]

 #if !PocketPC

-[assembly: AssemblyFileVersion("4.0.8.14707")]

+[assembly: AssemblyFileVersion("4.0.8.14710")]

 #endif

diff --git a/Src/Newtonsoft.Json.Tests/Serialization/ConstructorHandlingTests.cs b/Src/Newtonsoft.Json.Tests/Serialization/ConstructorHandlingTests.cs
index 1f8ade6..1d48a81 100644
--- a/Src/Newtonsoft.Json.Tests/Serialization/ConstructorHandlingTests.cs
+++ b/Src/Newtonsoft.Json.Tests/Serialization/ConstructorHandlingTests.cs
@@ -7,12 +7,13 @@ namespace Newtonsoft.Json.Tests.Serialization
   public class ConstructorHandlingTests : TestFixtureBase

   {

     [Test]

-    [ExpectedException(typeof(JsonSerializationException), ExpectedMessage = "Unable to find a constructor to use for type Newtonsoft.Json.Tests.TestObjects.PrivateConstructorTestClass. A class should either have a default constructor, one constructor with arguments or a constructor marked with the JsonConstructor attribute. Line 1, position 6.")]

-    public void FailWithPrivateConstructorAndDefault()

+    public void UsePrivateConstructorIfThereAreMultipleConstructorsWithParametersAndNothingToFallbackTo()

     {

       string json = @"{Name:""Name!""}";

 

-      JsonConvert.DeserializeObject<PrivateConstructorTestClass>(json);

+      var c = JsonConvert.DeserializeObject<PrivateConstructorTestClass>(json);

+

+      Assert.AreEqual("Name!", c.Name);

     }

 

     [Test]

diff --git a/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs b/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
index d568eec..0f7f7ff 100644
--- a/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
+++ b/Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs
@@ -1905,7 +1905,9 @@ keyword such as type of business.""
     }

 

     [Test]

-    [ExpectedException(typeof (JsonSerializationException), ExpectedMessage = @"Cannot deserialize JSON array into type 'Newtonsoft.Json.Tests.TestObjects.Person'. Line 1, position 1.")]

+    [ExpectedException(typeof(JsonSerializationException), ExpectedMessage = @"Cannot deserialize JSON array (i.e. [1,2,3]) into type 'Newtonsoft.Json.Tests.TestObjects.Person'.

+The deserialized type must be an array or implement a collection interface like IEnumerable, ICollection or IList.

+To force JSON arrays to deserialize add the JsonArrayAttribute to the type. Line 1, position 1.")]

     public void CannotDeserializeArrayIntoObject()

     {

       string json = @"[]";

@@ -1914,7 +1916,9 @@ keyword such as type of business.""
     }

 

     [Test]

-    [ExpectedException(typeof (JsonSerializationException), ExpectedMessage = @"Cannot deserialize JSON object into type 'System.Collections.Generic.List`1[Newtonsoft.Json.Tests.TestObjects.Person]'. Line 1, position 2.")]

+    [ExpectedException(typeof (JsonSerializationException), ExpectedMessage = @"Cannot deserialize JSON object (i.e. {""name"":""value""}) into type 'System.Collections.Generic.List`1[Newtonsoft.Json.Tests.TestObjects.Person]'.

+The deserialized type should be a normal .NET type (i.e. not a primitive type like integer, not a collection type like an array or List<T>) or a dictionary type (i.e. Dictionary<TKey, TValue>).

+To force JSON objects to deserialize add the JsonObjectAttribute to the type. Line 1, position 2.")]

     public void CannotDeserializeObjectIntoArray()

     {

       string json = @"{}";

@@ -5550,9 +5554,37 @@ Parameter name: value")]
       Assert.AreEqual("Pre", c2.PreField);

       Assert.AreEqual("Post", c2.PostField);

     }

+

+    [Test]

+    public void PrivateConstructor()

+    {

+      var person = PersonWithPrivateConstructor.CreatePerson();

+      person.Name = "John Doe";

+      person.Age = 25;

+

+      var serializedPerson = JsonConvert.SerializeObject(person);

+      var roundtrippedPerson = JsonConvert.DeserializeObject<PersonWithPrivateConstructor>(serializedPerson);

+

+      Assert.AreEqual(person.Name, roundtrippedPerson.Name);

+    }

 #endif

   }

 

+  public class PersonWithPrivateConstructor

+  {

+    private PersonWithPrivateConstructor()

+    { }

+

+    public static PersonWithPrivateConstructor CreatePerson()

+    {

+      return new PersonWithPrivateConstructor();

+    }

+

+    public string Name { get; set; }

+

+    public int Age { get; set; }

+  }

+

   public class DateTimeWrapper

   {

     public DateTime Value { get; set; }

diff --git a/Src/Newtonsoft.Json.Tests/TestObjects/PrivateConstructorTestClass.cs b/Src/Newtonsoft.Json.Tests/TestObjects/PrivateConstructorTestClass.cs
index ad52d17..698406d 100644
--- a/Src/Newtonsoft.Json.Tests/TestObjects/PrivateConstructorTestClass.cs
+++ b/Src/Newtonsoft.Json.Tests/TestObjects/PrivateConstructorTestClass.cs
@@ -33,5 +33,15 @@ namespace Newtonsoft.Json.Tests.TestObjects
     private PrivateConstructorTestClass()

     {

     }

+

+    // multiple constructors with arguments so the serializer doesn't know what to fall back to

+    private PrivateConstructorTestClass(object a)

+    {

+    }

+

+    // multiple constructors with arguments so the serializer doesn't know what to fall back to

+    private PrivateConstructorTestClass(object a, object b)

+    {

+    }

   }

 }
\ No newline at end of file
diff --git a/Src/Newtonsoft.Json/ConstructorHandling.cs b/Src/Newtonsoft.Json/ConstructorHandling.cs
index 591d150..123977b 100644
--- a/Src/Newtonsoft.Json/ConstructorHandling.cs
+++ b/Src/Newtonsoft.Json/ConstructorHandling.cs
@@ -36,11 +36,11 @@ namespace Newtonsoft.Json
   public enum ConstructorHandling

   {

     /// <summary>

-    /// First attempt to use the public default constructor then fall back to single paramatized constructor.

+    /// First attempt to use the public default constructor, then fall back to single paramatized constructor, then the non-public default constructor.

     /// </summary>

     Default = 0,

     /// <summary>

-    /// Allow Json.NET to use a non-public default constructor.

+    /// Json.NET will use a non-public default constructor before falling back to a paramatized constructor.

     /// </summary>

     AllowNonPublicDefaultConstructor = 1

   }

diff --git a/Src/Newtonsoft.Json/Properties/AssemblyInfo.cs b/Src/Newtonsoft.Json/Properties/AssemblyInfo.cs
index 73df4a0..4f81f4d 100644
--- a/Src/Newtonsoft.Json/Properties/AssemblyInfo.cs
+++ b/Src/Newtonsoft.Json/Properties/AssemblyInfo.cs
@@ -85,7 +85,7 @@ using System.Security;
 // by using the '*' as shown below:

 [assembly: AssemblyVersion("4.0.8.0")]

 #if !PocketPC

-[assembly: AssemblyFileVersion("4.0.8.14707")]

+[assembly: AssemblyFileVersion("4.0.8.14710")]

 #endif

 

 [assembly: CLSCompliant(true)]

diff --git a/Src/Newtonsoft.Json/Serialization/JsonContract.cs b/Src/Newtonsoft.Json/Serialization/JsonContract.cs
index db38243..8a399a4 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonContract.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonContract.cs
@@ -119,7 +119,7 @@ namespace Newtonsoft.Json.Serialization
     public Func<object> DefaultCreator { get; set; }

 

     /// <summary>

-    /// Gets or sets a value indicating whether [default creator non public].

+    /// Gets or sets a value indicating whether the default creator is non public.

     /// </summary>

     /// <value><c>true</c> if the default object creator is non-public; otherwise, <c>false</c>.</value>

     public bool DefaultCreatorNonPublic { get; set; }

diff --git a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
index 2a81a8a..7556323 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
@@ -468,7 +468,9 @@ namespace Newtonsoft.Json.Serialization
 #endif

       }

 

-      throw CreateSerializationException(reader, "Cannot deserialize JSON object into type '{0}'.".FormatWith(CultureInfo.InvariantCulture, objectType));

+      throw CreateSerializationException(reader, @"Cannot deserialize JSON object (i.e. {{""name"":""value""}}) into type '{0}'.

+The deserialized type should be a normal .NET type (i.e. not a primitive type like integer, not a collection type like an array or List<T>) or a dictionary type (i.e. Dictionary<TKey, TValue>).

+To force JSON objects to deserialize add the JsonObjectAttribute to the type.".FormatWith(CultureInfo.InvariantCulture, objectType));

     }

 

     private JsonArrayContract EnsureArrayContract(JsonReader reader, Type objectType, JsonContract contract)

@@ -478,7 +480,9 @@ namespace Newtonsoft.Json.Serialization
 

       JsonArrayContract arrayContract = contract as JsonArrayContract;

       if (arrayContract == null)

-        throw CreateSerializationException(reader, "Cannot deserialize JSON array into type '{0}'.".FormatWith(CultureInfo.InvariantCulture, objectType));

+        throw CreateSerializationException(reader, @"Cannot deserialize JSON array (i.e. [1,2,3]) into type '{0}'.

+The deserialized type must be an array or implement a collection interface like IEnumerable, ICollection or IList.

+To force JSON arrays to deserialize add the JsonArrayAttribute to the type.".FormatWith(CultureInfo.InvariantCulture, objectType));

 

       return arrayContract;

     }

@@ -954,8 +958,12 @@ namespace Newtonsoft.Json.Serialization
         newObject = contract.OverrideConstructor.Invoke(null);

       }

       else if (contract.DefaultCreator != null &&

-        (!contract.DefaultCreatorNonPublic || Serializer.ConstructorHandling == ConstructorHandling.AllowNonPublicDefaultConstructor))

+        (!contract.DefaultCreatorNonPublic || Serializer.ConstructorHandling == ConstructorHandling.AllowNonPublicDefaultConstructor || contract.ParametrizedConstructor == null))

       {

+        // use the default constructor if it is...

+        // public

+        // non-public and the user has change constructor handling settings

+        // non-public and there is no other constructor

         newObject = contract.DefaultCreator();

       }

       else if (contract.ParametrizedConstructor != null)