Json.Net DeserializeObject失败，出现OData.Delta-仅限整数 [英] Json.Net DeserializeObject failing with OData.Delta - integers only
问题描述
此问题正在影响我的ASP.Net WebApi修补程序方法，该方法看起来非常像这样:
This problem is affecting my ASP.Net WebApi Patch method which looks a lot like this:
public MyModel Patch(int id, [FromBody]Delta<MyModel> newRecord){/*stuff here*/}
但这不是WebApi的问题-故障出在Json.Net和OData.Delta之间.
But it's not WebApi that's the problem - the failure is between Json.Net and OData.Delta.
问题是 JsonConvert.DeserializeObject看不到OData.Delta对象的整数，我想知道是否有解决方法或可以应用的修复程序.
The problem is JsonConvert.DeserializeObject does not see integers of OData.Delta objects and I'm wondering if there's a workaround or fix I can apply.
更新:在Json.Net库中已经编写了代码(请参见右下方)，可以解决此问题.只需要将它包含在下一个更新中(如果James Newton-King允许)
更新2:经过进一步测试，我认为最好的做法是停止使用OData.Delta并编写自己的代码(请参见答案)
单元测试以证明问题存在(为清楚起见，使用下面的语句)
Unit tests to prove the problem exists (using statements moved below for clarity)
测试1:使用int(Int32)失败:
Test 1: Fails with an int (Int32):
class TestObjWithInt
{
public int Int { get; set; }
}
[TestMethod]
public void IsApplied_When_IntIsDeserializedToDelta()
{
string testData = "{\"Int\":1}";
var deserializedDelta = JsonConvert.DeserializeObject<Delta<TestObjWithInt>>(testData);
var result = deserializedDelta.GetChangedPropertyNames().Contains("Int");
Assert.IsTrue(result);
}
测试2:成功使用长整数(Int64)
Test 2: Succeeds with a long (Int64)
class TestObjWithLong
{
public long Long { get; set; }
}
[TestMethod]
public void IsApplied_When_LongIsDeserializedToDelta()
{
string testData = "{\"Long\":1}";
var deserializedDelta = JsonConvert.DeserializeObject<Delta<TestObjWithLong>>(testData);
var result = deserializedDelta.GetChangedPropertyNames().Contains("Long");
Assert.IsTrue(result);
}
并且为了确保反序列化从一开始就起作用，这两个测试都通过了.
And just to be sure that deserialization works to begin with, these two tests both pass.
[TestMethod]
public void IsApplied_When_LongIsDeserializedToTestObject()
{
string testData = "{\"Long\":1}";
var deserializedObject = JsonConvert.DeserializeObject<TestObjWithLong>(testData);
var result = deserializedObject.Long == 1;
Assert.IsTrue(result);
}
[TestMethod]
public void IsApplied_When_IntIsDeserializedToTestObject()
{
string testData = "{\"Int\":1}";
var deserializedObject = JsonConvert.DeserializeObject<TestObjWithInt>(testData);
var result = deserializedObject.Int == 1;
Assert.IsTrue(result);
}
我发现了此 OData错误报告，听起来像是一个类似的问题，但是它已经过时并且已经关闭，因此可能不是.
I found this OData bug report which sounds like a similar issue but its old and closed so probably not.
任何帮助都会很棒.
使用语句(从测试文件的顶部开始):
Using statements (from the top of the test file):
using System;
using System.Linq;
using System.Web.Http.OData;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
解决方案，如果被James Newton-King接受-更改为版本6.0.6. 替换JsonSerializerInternalReader.cs第1581行:
Solution if accepted by James Newton-King - change to release 6.0.6. Replace JsonSerializerInternalReader.cs line 1581:
contract.TrySetMember(newObject, memberName, value);
具有:
bool done = false;
while (!(done = done || contract.TrySetMember(newObject, memberName, value)))
{
switch (reader.TokenType)
{
case JsonToken.Integer:
if (value is long && ((long)value) <= Int32.MaxValue && ((long)value) >= Int32.MinValue)
value = Convert.ToInt32(value);
//Add else if (...) to cast to other data types here (none additional required to date).
else
done = true;
break;
default:
done = true;
break;
}
}
推荐答案
OData.Delta< T>对于Int64以外的任何其他数字类型，均不能与Json.Net一起使用.最简单的方法是编写OData.Delta T的替换. (这是我在公司时间所做的，因此无法完整地发布)，包含以下方法:
OData.Delta<T> does not work with Json.Net for any number Types other than Int64. The easiest approach is to write a replacement for OData.Delta<T> (which I've done on company time so I can't post it in its entirety sorry) containing methods like this:
private bool TrySetInt32(object value, PropertyInfo propertyInfo, bool isNullable)
{
var done = false;
if (value is Int32)
{
propertyInfo.SetValue(_obj, value);
done = true;
}
else if (value == null)
{
if (isNullable)
{
propertyInfo.SetValue(_obj, value);
done = true;
}
}
else if (value is Int64) //Json.Net - fallback for numbers is an Int64
{
var val = (Int64)value;
if (val <= Int32.MaxValue && val >= Int32.MinValue)
{
done = true;
propertyInfo.SetValue(_obj, Convert.ToInt32(val));
}
}
else
{
Int32 val;
done = Int32.TryParse(value.ToString(), out val);
if (done)
propertyInfo.SetValue(_obj, val);
}
return done;
}
该类可以是这样的动态泛型:
The class can be a dynamic generic like this:
public sealed class Patchable<T> : DynamicObject where T : class, new()
具有这样的工作变量:
T _obj = new T();
在覆盖的TrySetMember方法中，我们需要使用反射检查属性的基础类型，并调用适当的TrySet ...方法，如下所示:
In the overridden TrySetMember method, we need to check the underlying type of the property using reflection and call the appropriate TrySet... method like this:
if (underlyingType == typeof(Int16))
done = TrySetInt16(value, propertyInfo, isNullable);
else if (underlyingType == typeof(Int32))
done = TrySetInt32(value, propertyInfo, isNullable);
如果成功设置了值，我们可以将属性名称添加到列表中，然后我们可以使用该列表来修补原始记录，如下所示:
If the value is set successfully we can add the property name to a list that we can then use for patching the original record like this:
if (done)
_changedPropertyNames.Add(propertyInfo.Name);
public void Patch(T objectToPatch)
{
foreach (var propertyName in _changedPropertyNames)
{
var propertyInfo = _obj.GetType().GetProperty(propertyName);
propertyInfo.SetValue(objectToPatch, propertyInfo.GetValue(_obj));
}
}
68个单元测试之后，一切似乎都运行良好.这是一个示例:
68 unit tests later, it all seems to work pretty well. Here's an example:
class TestObjWithInt32
{
public Int32 Int32 { get; set; }
public Int32? SetNullable { get; set; }
public Int32? UnsetNullable { get; set; }
}
[TestMethod]
public void IsApplied_When_Int32IsDeserializedToPatchable()
{
string testData = "{\"Int32\":1,\"SetNullable\":1}";
var deserializedPatchable = JsonConvert.DeserializeObject<Patchable<TestObjWithInt32>>(testData);
var result = deserializedPatchable.ChangedPropertyNames.Contains("Int32");
Assert.IsTrue(result);
var patchedObject = new TestObjWithInt32();
Assert.AreEqual<Int32>(0, patchedObject.Int32);
deserializedPatchable.Patch(patchedObject);
Assert.AreEqual<Int32>(1, patchedObject.Int32);
Assert.IsNull(patchedObject.UnsetNullable);
Assert.IsNotNull(patchedObject.SetNullable);
}
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