C# 如何配置JSON.net反序列化程序以跟踪丢失的属性?
示例类:C# 如何配置JSON.net反序列化程序以跟踪丢失的属性?,c#,json.net,C#,Json.net,示例类: public class ClassA { public int Id { get; set; } public string SomeString { get; set; } public int? SomeInt { get; set; } } 默认反序列化程序: var myObject = JsonConvert.DeserializeObject<ClassA>(str); 或 如何跟踪反序列化过程中丢失的属性并保持相同的行为?是否有方
public class ClassA
{
public int Id { get; set; }
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
默认反序列化程序:
var myObject = JsonConvert.DeserializeObject<ClassA>(str);
或
如何跟踪反序列化过程中丢失的属性并保持相同的行为?是否有方法覆盖某些JSON.net序列化程序方法(例如DefaultContractResolver类方法)以实现此目的。例如:
List<string> missingProps;
var myObject = JsonConvert.DeserializeObject<ClassA>(str, settings, missingProps);
列出丢失的道具;
var myObject=JsonConvert.DeserializeObject(str、settings、missingProps);
对于第一个输入,列表应包含缺少属性的名称(“SomeString”、“SomeInt”),对于第二个输入,列表应为空。反序列化对象保持不变。1。JSON具有类中缺少的属性
使用属性,您可以说缺少的属性是否作为错误处理
然后您可以安装将注册错误的委托
这将检测JSON字符串中是否存在一些“垃圾”属性
public class ClassA
{
public int Id { get; set; }
public string SomeString { get; set; }
}
internal class Program
{
private static void Main(string[] args)
{
const string str = "{'Id':5, 'FooBar': 42 }";
var myObject = JsonConvert.DeserializeObject<ClassA>(str
, new JsonSerializerSettings
{
Error = OnError,
MissingMemberHandling = MissingMemberHandling.Error
});
Console.ReadKey();
}
private static void OnError(object sender, ErrorEventArgs args)
{
Console.WriteLine(args.ErrorContext.Error.Message);
args.ErrorContext.Handled = true;
}
}
备选案文2:
使用一些“特殊”值作为默认值,然后进行检查
public class ClassB
{
public int Id { get; set; }
[DefaultValue("NOTSET")]
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
internal class Program
{
private static void Main(string[] args)
{
const string str = "{ 'Id':5 }";
var myObject = JsonConvert.DeserializeObject<ClassB>(str
, new JsonSerializerSettings
{
DefaultValueHandling = DefaultValueHandling.Populate
});
if (myObject.SomeString == "NOTSET")
{
Console.WriteLine("no value provided for property SomeString");
}
Console.ReadKey();
}
}
反序列化期间查找空/未定义标记的另一种方法是编写自定义的
JsonConverter
,下面是一个自定义转换器的示例,它可以报告省略的标记(例如“{Id':5}”
)和空标记(例如{“Id”:5,“SomeString”:null,“somesint”:null}
)
公共类NullReportConverter:JsonConverter
{
私有只读列表_nullproperties=new List();
public bool ReportDefinedNullTokens{get;set;}
公共IEnumerable空属性
{
获取{return}nullproperties;}
}
公共空间清除()
{
_nullproperties.Clear();
}
公共覆盖布尔CanConvert(类型objectType)
{
返回true;
}
公共重写对象ReadJson(JsonReader阅读器,类型objectType,对象existingValue,JsonSerializer序列化程序)
{
existingValue=existingValue??Activator.CreateInstance(objectType,true);
var jObject=jObject.Load(读卡器);
var特性=
GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
foreach(属性中的var属性)
{
var jToken=jObject[property.Name];
如果(jToken==null)
{
_添加(属性);
继续;
}
var值=jToken.ToObject(property.PropertyType);
if(ReportDefinedNullTokens&&value==null)
_添加(属性);
SetValue(existingValue,value,null);
}
返回现有值;
}
//注意:如果我们只想使用转换器进行反序列化,我们可以省略writer部分
公共重写void WriteJson(JsonWriter编写器、对象值、JsonSerializer序列化器)
{
var objectType=value.GetType();
var特性=
GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
writer.WriteStartObject();
foreach(属性中的var属性)
{
var propertyValue=property.GetValue(值,null);
writer.WritePropertyName(property.Name);
serializer.Serialize(writer,propertyValue);
}
writer.WriteEndObject();
}
}
注意:如果不需要将Writer部分用于序列化对象,则可以省略它。
用法示例:
class Foo
{
public int Id { get; set; }
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
class Program
{
static void Main(string[] args)
{
var nullConverter=new NullReportConverter();
Console.WriteLine("Pass 1");
var obj0 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5, \"Id\":5}", nullConverter);
foreach(var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
Console.WriteLine("Pass2");
var obj1 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}" , nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
nullConverter.ReportDefinedNullTokens = true;
Console.WriteLine("Pass3");
var obj2 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}", nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
}
}
class-Foo
{
公共int Id{get;set;}
公共字符串SomeString{get;set;}
公共int?SomeInt{get;set;}
}
班级计划
{
静态void Main(字符串[]参数)
{
var nullConverter=新的NullReportConverter();
控制台写入线(“通过1”);
var obj0=JsonConvert.DeserializeObject(“{\'Id\':5,\'Id\':5}”,nullConverter);
foreach(nullConverter.NullProperties中的var p)
控制台写入线(p);
nullConverter.Clear();
控制台写入线(“Pass2”);
var obj1=JsonConvert.DeserializeObject(“{\'Id\':5,\'SomeString\':null,\'SomeInt\':null}”,nullConverter);
foreach(nullConverter.NullProperties中的var p)
控制台写入线(p);
nullConverter.Clear();
nullConverter.ReportDefinedNullTokens=true;
控制台写入线(“Pass3”);
var obj2=JsonConvert.DeserializeObject(“{\'Id\':5,\'SomeString\':null,\'SomeInt\':null}”,nullConverter);
foreach(nullConverter.NullProperties中的var p)
控制台写入线(p);
}
}
我遇到了这个问题,但由于POCO对象,defaultValue不是解决方案。我认为这是一种比NullReportConverter更简单的方法。
有三个单元测试。Root是封装整个json的类。键是属性的类型。希望这对别人有帮助
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
namespace SomeNamespace {
[TestClass]
public class NullParseJsonTest {
[TestMethod]
public void TestMethod1()
{
string slice = "{Key:{guid:\"asdf\"}}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNotNull(result.OptionalKey.Value);
Assert.AreEqual("asdf", result.OptionalKey.Value.Guid);
}
[TestMethod]
public void TestMethod2()
{
string slice = "{Key:null}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
[TestMethod]
public void TestMethod3()
{
string slice = "{}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsFalse(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
}
class Root {
public Key Key {
get {
return OptionalKey.Value;
}
set {
OptionalKey.Value = value;
OptionalKey.IsSet = true; // This does the trick, it is never called by JSON.NET if attribute missing
}
}
[JsonIgnore]
public Optional<Key> OptionalKey = new Optional<Key> { IsSet = false };
};
class Key {
public string Guid { get; set; }
}
class Optional<T> {
public T Value { get; set; }
public bool IsSet { get; set; }
}
}
使用Microsoft.VisualStudio.TestTools.UnitTesting;
使用Newtonsoft.Json;
名称空间名称空间{
[测试类]
公共类NullParseJsonTest{
[测试方法]
公共void TestMethod1()
{
string slice=“{Key:{guid:\“asdf\”}}”;
var result=JsonConvert.DeserializeObject(切片);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNotNull(result.OptionalKey.Value);
AreEqual(“asdf”,result.OptionalKey.Value.Guid);
}
[测试方法]
公共void TestMethod2()
{
string slice=“{Key:null}”;
var result=JsonConvert.DeserializeObject(切片);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
[测试方法]
公共void TestMethod3()
{
字符串slice=“{}”;
var result=JsonConvert.DeserializeObject(切片);
Assert.IsFalse(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
}
类根{
公钥{
得到{
返回OptionalKey.Value;
}
设置{
OptionalKey.Value=值;
OptionalKey.IsSet=true;//这就成功了,它永远不会被调用
public class ClassB
{
public int Id { get; set; }
[DefaultValue("NOTSET")]
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
internal class Program
{
private static void Main(string[] args)
{
const string str = "{ 'Id':5 }";
var myObject = JsonConvert.DeserializeObject<ClassB>(str
, new JsonSerializerSettings
{
DefaultValueHandling = DefaultValueHandling.Populate
});
if (myObject.SomeString == "NOTSET")
{
Console.WriteLine("no value provided for property SomeString");
}
Console.ReadKey();
}
}
public class ClassC
{
public int Id { get; set; }
[DefaultValue("NOTSET")]
public string SomeString { get; set; }
public int? SomeInt { get; set; }
public void Verify()
{
if (SomeInt == null ) throw new JsonSerializationException("SomeInt not set!");
if (SomeString == "NOTSET") throw new JsonSerializationException("SomeString not set!");
}
}
public class NullReportConverter : JsonConverter
{
private readonly List<PropertyInfo> _nullproperties=new List<PropertyInfo>();
public bool ReportDefinedNullTokens { get; set; }
public IEnumerable<PropertyInfo> NullProperties
{
get { return _nullproperties; }
}
public void Clear()
{
_nullproperties.Clear();
}
public override bool CanConvert(Type objectType)
{
return true;
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
existingValue = existingValue ?? Activator.CreateInstance(objectType, true);
var jObject = JObject.Load(reader);
var properties =
objectType.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
foreach (var property in properties)
{
var jToken = jObject[property.Name];
if (jToken == null)
{
_nullproperties.Add(property);
continue;
}
var value = jToken.ToObject(property.PropertyType);
if(ReportDefinedNullTokens && value ==null)
_nullproperties.Add(property);
property.SetValue(existingValue, value, null);
}
return existingValue;
}
//NOTE: we can omit writer part if we only want to use the converter for deserializing
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
var objectType = value.GetType();
var properties =
objectType.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
writer.WriteStartObject();
foreach (var property in properties)
{
var propertyValue = property.GetValue(value, null);
writer.WritePropertyName(property.Name);
serializer.Serialize(writer, propertyValue);
}
writer.WriteEndObject();
}
}
class Foo
{
public int Id { get; set; }
public string SomeString { get; set; }
public int? SomeInt { get; set; }
}
class Program
{
static void Main(string[] args)
{
var nullConverter=new NullReportConverter();
Console.WriteLine("Pass 1");
var obj0 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5, \"Id\":5}", nullConverter);
foreach(var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
Console.WriteLine("Pass2");
var obj1 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}" , nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
nullConverter.Clear();
nullConverter.ReportDefinedNullTokens = true;
Console.WriteLine("Pass3");
var obj2 = JsonConvert.DeserializeObject<Foo>("{\"Id\":5,\"SomeString\":null,\"SomeInt\":null}", nullConverter);
foreach (var p in nullConverter.NullProperties)
Console.WriteLine(p);
}
}
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Newtonsoft.Json;
namespace SomeNamespace {
[TestClass]
public class NullParseJsonTest {
[TestMethod]
public void TestMethod1()
{
string slice = "{Key:{guid:\"asdf\"}}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNotNull(result.OptionalKey.Value);
Assert.AreEqual("asdf", result.OptionalKey.Value.Guid);
}
[TestMethod]
public void TestMethod2()
{
string slice = "{Key:null}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsTrue(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
[TestMethod]
public void TestMethod3()
{
string slice = "{}";
var result = JsonConvert.DeserializeObject<Root>(slice);
Assert.IsFalse(result.OptionalKey.IsSet);
Assert.IsNull(result.OptionalKey.Value);
}
}
class Root {
public Key Key {
get {
return OptionalKey.Value;
}
set {
OptionalKey.Value = value;
OptionalKey.IsSet = true; // This does the trick, it is never called by JSON.NET if attribute missing
}
}
[JsonIgnore]
public Optional<Key> OptionalKey = new Optional<Key> { IsSet = false };
};
class Key {
public string Guid { get; set; }
}
class Optional<T> {
public T Value { get; set; }
public bool IsSet { get; set; }
}
}