如何在C#中将JSON对象序列化或反序列化到一定深度？_C#_.net_Json_Serialization

如何在C#中将JSON对象序列化或反序列化到一定深度？

c# .net json serialization

如何在C#中将JSON对象序列化或反序列化到一定深度？,c#,.net,json,serialization,C#,.net,Json,Serialization,我只想要对象的第一个深度级别（我不想要任何子级）。我愿意使用任何可用的图书馆。大多数库仅在达到递归深度时抛出异常，而不是忽略异常。如果这是不可能的，有没有一种方法可以忽略给定特定数据类型的特定成员的序列化编辑：假设我有这样一个对象： class MyObject { String name = "Dan"; int age = 88; List<Children> myChildren = ...(lots of children with lots of

我只想要对象的第一个深度级别（我不想要任何子级）。我愿意使用任何可用的图书馆。大多数库仅在达到递归深度时抛出异常，而不是忽略异常。如果这是不可能的，有没有一种方法可以忽略给定特定数据类型的特定成员的序列化

编辑：假设我有这样一个对象：

class MyObject
{
    String name = "Dan";
    int age = 88;
    List<Children> myChildren = ...(lots of children with lots of grandchildren);
}

类MyObject
{
字符串name=“Dan”；
年龄=88岁；
列出我的孩子=…（很多孩子有很多孙子）；
}

我想删除所有子对象（甚至是复杂类型）以返回如下对象：

class MyObject
{
    String name = "Dan";
    int age = 88;
    List<Children> myChildren = null;
}

类MyObject
{
字符串name=“Dan”；
年龄=88岁；
List myChildren=null；
}

在和序列化程序之间使用某种协调是可能的

自定义

JsonWriter

在对象启动时递增计数器，然后在对象结束时再次递减计数器

public class CustomJsonTextWriter : JsonTextWriter
{
    public CustomJsonTextWriter(TextWriter textWriter) : base(textWriter) {}

    public int CurrentDepth { get; private set; }

    public override void WriteStartObject()
    {
        CurrentDepth++;
        base.WriteStartObject();
    }

    public override void WriteEndObject()
    {
        CurrentDepth--;
        base.WriteEndObject();
    }
}

自定义的

ContractResolver

对所有用于验证当前深度的属性应用特殊谓词

public class CustomContractResolver : DefaultContractResolver
{
    private readonly Func<bool> _includeProperty;

    public CustomContractResolver(Func<bool> includeProperty)
    {
        _includeProperty = includeProperty;
    }

    protected override JsonProperty CreateProperty(
        MemberInfo member, MemberSerialization memberSerialization)
    {
        var property = base.CreateProperty(member, memberSerialization);
        var shouldSerialize = property.ShouldSerialize;
        property.ShouldSerialize = obj => _includeProperty() &&
                                          (shouldSerialize == null ||
                                           shouldSerialize(obj));
        return property;
    }
}

您可以使用反射来检查对象，并制作一个副本，根据需要更改每个属性值。巧合的是，我刚刚公开了一个新的图书馆，使这类事情变得非常容易。你可以在这里找到它：

下面是一个您将使用的代码示例

var newInstance = ObjectMapper.Map(obj,(value,del) => {
    return value !=null && value.GetType().IsClass ?
        null :
        value;
    });

“Map”方法迭代对象的每个属性，并为每个属性调用

Func

（IDelegateInfo具有反射信息，如属性名称、类型等）。函数返回每个属性的新值。所以在这个例子中，我只是测试每个属性的值，看看它是否是一个类，如果是，则返回null；如果不是，则返回原始值

另一种更具表现力的方式：

var obj = new MyObject();

// map the object to a new dictionary        

var dict = ObjectMapper.ToDictionary(obj);

// iterate through each item in the dictionary, a key/value pair
// representing each property 

foreach (KeyValuePair<string,object> kvp in dict) {
    if (kvp.Value!=null && kvp.Value.GetType().IsClass) {
        dict[kvp.Key]=null;
    }
}

// map back to an instance

var newObject = ObjectMapper.ToNew<MyObject>(dict);

但如果json仅仅是达到目的的一种手段，我就不会涉及它；如果您想留在CLR对象中，那么就不需要使用JSON作为中介。

首先，我想说的是，所有的功劳都应该归于Nathan Baulch。这是对他的答案的改编，并结合使用MaxDepth in设置。谢谢你的帮助，内森

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Web;
using System.Web.Mvc;

namespace Helpers
{
    public class JsonNetResult : JsonResult
    {
        public JsonNetResult()
        {
            Settings = new JsonSerializerSettings
            {
                ReferenceLoopHandling = ReferenceLoopHandling.Error
            };
        }

        public JsonSerializerSettings Settings { get; private set; }

        public override void ExecuteResult(ControllerContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            if (this.JsonRequestBehavior == JsonRequestBehavior.DenyGet && string.Equals(context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException("JSON GET is not allowed");

            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = string.IsNullOrEmpty(this.ContentType) ? "application/json" : this.ContentType;

            if (this.ContentEncoding != null)
                response.ContentEncoding = this.ContentEncoding;
            if (this.Data == null)
                return;

            var scriptSerializer = JsonSerializer.Create(this.Settings);

            using (var sw = new StringWriter())
            {
                if (Settings.MaxDepth != null)
                {
                    using (var jsonWriter = new JsonNetTextWriter(sw))
                    {
                        Func<bool> include = () => jsonWriter.CurrentDepth <= Settings.MaxDepth;
                        var resolver = new JsonNetContractResolver(include);
                        this.Settings.ContractResolver = resolver;
                        var serializer = JsonSerializer.Create(this.Settings);
                        serializer.Serialize(jsonWriter, Data);
                    }
                    response.Write(sw.ToString());
                }
                else
                {
                    scriptSerializer.Serialize(sw, this.Data);
                    response.Write(sw.ToString());
                }
            }
        }
    }

    public class JsonNetTextWriter : JsonTextWriter
    {
        public JsonNetTextWriter(TextWriter textWriter) : base(textWriter) { }

        public int CurrentDepth { get; private set; }

        public override void WriteStartObject()
        {
            CurrentDepth++;
            base.WriteStartObject();
        }

        public override void WriteEndObject()
        {
            CurrentDepth--;
            base.WriteEndObject();
        }
    }

    public class JsonNetContractResolver : DefaultContractResolver
    {
        private readonly Func<bool> _includeProperty;

        public JsonNetContractResolver(Func<bool> includeProperty)
        {
            _includeProperty = includeProperty;
        }

        protected override JsonProperty CreateProperty(
            MemberInfo member, MemberSerialization memberSerialization)
        {
            var property = base.CreateProperty(member, memberSerialization);
            var shouldSerialize = property.ShouldSerialize;
            property.ShouldSerialize = obj => _includeProperty() &&
                                              (shouldSerialize == null ||
                                               shouldSerialize(obj));
            return property;
        }
    }
}

使用Newtonsoft.Json；
使用Newtonsoft.Json.Serialization；
使用制度；
使用System.Collections.Generic；
使用System.IO；
使用System.Linq；
运用系统反思；
使用System.Web；
使用System.Web.Mvc；
命名空间帮助程序
{
公共类JsonNetResult:JsonResult
{
公共JsonNetResult（）
{
设置=新JsonSerializerSettings
{
ReferenceLoopHandling=ReferenceLoopHandling.Error
};
}
公共JsonSerializerSettings设置{get；private set；}
公共覆盖无效ExecuteSult（ControllerContext上下文）
{
if（上下文==null）
抛出新的ArgumentNullException（“上下文”）；
if（this.JsonRequestBehavior==JsonRequestBehavior.DenyGet&&string.Equals（context.HttpContext.Request.HttpMethod，“GET”，StringComparison.OrdinalIgnoreCase））
抛出新的InvalidOperationException（“不允许JSON获取”）；
HttpResponseBase response=context.HttpContext.response；
response.ContentType=string.IsNullOrEmpty（this.ContentType）？“application/json”：this.ContentType；
if（this.ContentEncoding！=null）
response.ContentEncoding=this.ContentEncoding；
if（this.Data==null）
返回；
var scriptSerializer=JsonSerializer.Create（this.Settings）；
使用（var sw=new StringWriter（））
{
如果（Settings.MaxDepth！=null）
{
使用（var jsonWriter=new jsonnetextwriter（sw））
{
Func include=（）=>jsonWriter.CurrentDepth\u includeProperty（）&&
（shouldSerialize==null||
应该序列化（obj））；
归还财产；
}
}
}

使用：

//实例化JsonNetResult以处理循环引用问题。
var result=new JsonNetResult
{
数据=，
JsonRequestBehavior=JsonRequestBehavior.AllowGet，
背景=
{
ReferenceLoopHandling=ReferenceLoopHandling.Ignore，
MaxDepth=1
}
};
返回结果；

如果您想在ASP.NET核心项目中使用此功能，可能无法实现自己的JsonTextWriter。但您可以自定义DefaultContractResolver和IValueProvider

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Linq;

namespace customserialization
{
    /// <summary>
    /// IValueProvider personalizado  para manejar max depth level
    /// </summary>
    public class CustomDynamicValueProvider : DynamicValueProvider, IValueProvider
    {
        MemberInfo _memberInfo;
        MaxDepthHandler _levelHandler;

        public CustomDynamicValueProvider(MemberInfo memberInfo, MaxDepthHandler levelHandler) : base(memberInfo)
        {
            _memberInfo = memberInfo;
            _levelHandler = levelHandler;
        }

        public new object GetValue(object target)
        {
            //Si el valor a serializar es un objeto se incrementa el nivel de profundidad. En el caso de las listas el nivel se incrementa en el evento OnSerializing
            if (((PropertyInfo)_memberInfo).PropertyType.IsClass) this._levelHandler.IncrementLevel();

            var rv = base.GetValue(target);

            //Al finalizar la obtención del valor se decrementa. En el caso de las listas el nivel se decrementa en el evento OnSerialized
            if (((PropertyInfo)_memberInfo).PropertyType.IsClass) this._levelHandler.DecrementLevel();

            return rv;
        }
    }

    /// <summary>
    /// Maneja los niveles de serialización
    /// </summary>
    public class MaxDepthHandler
    {
        int _maxDepth;
        int _currentDepthLevel;

        /// <summary>
        /// Nivel actual
        /// </summary>
        public int CurrentDepthLevel { get { return _currentDepthLevel; } }

        public MaxDepthHandler(int maxDepth)
        {
            this._currentDepthLevel = 1;
            this._maxDepth = maxDepth;
        }

        /// <summary>
        /// Incrementa el nivel actual
        /// </summary>
        public void IncrementLevel()
        {
            this._currentDepthLevel++;
        }

        /// <summary>
        /// Decrementa el nivel actual
        /// </summary>
        public void DecrementLevel()
        {
            this._currentDepthLevel--;
        }

        /// <summary>
        /// Determina si se alcanzó el nivel actual
        /// </summary>
        /// <returns></returns>
        public bool IsMaxDepthLevel()
        {
            return !(this._currentDepthLevel < this._maxDepth);
        }
    }

    public class ShouldSerializeContractResolver : DefaultContractResolver
    {

        MaxDepthHandler _levelHandler;

        public ShouldSerializeContractResolver(int maxDepth)
        {
            this._levelHandler = new MaxDepthHandler(maxDepth);
        }


        void OnSerializing(object o, System.Runtime.Serialization.StreamingContext context)
        {
            //Antes de serializar una lista se incrementa el nivel. En el caso de los objetos el nivel se incrementa en el método GetValue del IValueProvider
            if (o.GetType().IsGenericList())
                _levelHandler.IncrementLevel();
        }

        void OnSerialized(object o, System.Runtime.Serialization.StreamingContext context)
        {
            //Despues de serializar una lista se decrementa el nivel. En el caso de los objetos el nivel se decrementa en el método GetValue del IValueProvider
            if (o.GetType().IsGenericList())
                _levelHandler.DecrementLevel();
        }

        protected override JsonContract CreateContract(Type objectType)
        {
            var contract = base.CreateContract(objectType);
            contract.OnSerializingCallbacks.Add(new SerializationCallback(OnSerializing));
            contract.OnSerializedCallbacks.Add(new SerializationCallback(OnSerialized));

            return contract;
        }


        protected override IValueProvider CreateMemberValueProvider(MemberInfo member)
        {
            var rv = base.CreateMemberValueProvider(member);

            if (rv is DynamicValueProvider) //DynamicValueProvider es el valueProvider usado en general
            {
                //Utilizo mi propio ValueProvider, que utilizar el levelHandler
                rv = new CustomDynamicValueProvider(member, this._levelHandler);
            }

            return rv;
        }

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
        {
            JsonProperty property = base.CreateProperty(member, memberSerialization);

            var isObjectOrList = ((PropertyInfo)member).PropertyType.IsGenericList() || ((PropertyInfo)member).PropertyType.IsClass;



            property.ShouldSerialize =
                    instance =>
                    {
                        var shouldSerialize = true;
                        //Si se alcanzo el nivel maximo y la propiedad (member) actual a serializar es un objeto o lista no se serializa (shouldSerialize = false)
                        if (_levelHandler.IsMaxDepthLevel() && isObjectOrList)
                            shouldSerialize = false;                        

                        return shouldSerialize;
                    };

            return property;
        }



    }

    public static class Util
    {
        public static bool IsGenericList(this Type type)
        {
            foreach (Type @interface in type.GetInterfaces())
            {
                if (@interface.IsGenericType)
                {
                    if (@interface.GetGenericTypeDefinition() == typeof(ICollection<>))
                    {
                        // if needed, you can also return the type used as generic argument
                        return true;
                    }
                }
            }
            return false;
        }
    }
}

你能举一些JSON问题的例子吗？你能创建一个没有任何子对象的新对象并序列化它吗？从逻辑上讲这是有意义的，但我想去掉任何object类型的对象的子对象。我认为JSON序列化将是最好的方法，但我绝对愿意接受建议。我不能让它在ac中工作库Json.Net的实际版本。似乎从未调用CustomContractResolver方法。抱歉，我错过了其中明确说明的部分：CreatePROPERTY…我的坏。普通成员需要更多的了解吗？有解决方案吗？很遗憾，没有处理这个问题。我添加了这个类，它工作得非常好。尽管我的child节点是一个列表，出于某种原因，我的结束节点包含空对象而不是无对象。是否有办法防止这种情况发生？它可能无法工作，因为这里有对已释放闭包的访问：

Func include=（）=>jsonWriter.CurrentDepth我喜欢这个解决方案主要是因为我可以保持当前的JsonSerializerSettings
值。问题是CurrentDepthLevel永远不会重置，所以它只在每个控制器方法上序列化一次时起作用。如果需要序列化多个对象（或多次）如果你想重新使用分解器，你会有麻烦的。
string json = JavaScriptSerializer.Serialize(newObject);

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Web;
using System.Web.Mvc;

namespace Helpers
{
    public class JsonNetResult : JsonResult
    {
        public JsonNetResult()
        {
            Settings = new JsonSerializerSettings
            {
                ReferenceLoopHandling = ReferenceLoopHandling.Error
            };
        }

        public JsonSerializerSettings Settings { get; private set; }

        public override void ExecuteResult(ControllerContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            if (this.JsonRequestBehavior == JsonRequestBehavior.DenyGet && string.Equals(context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException("JSON GET is not allowed");

            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = string.IsNullOrEmpty(this.ContentType) ? "application/json" : this.ContentType;

            if (this.ContentEncoding != null)
                response.ContentEncoding = this.ContentEncoding;
            if (this.Data == null)
                return;

            var scriptSerializer = JsonSerializer.Create(this.Settings);

            using (var sw = new StringWriter())
            {
                if (Settings.MaxDepth != null)
                {
                    using (var jsonWriter = new JsonNetTextWriter(sw))
                    {
                        Func<bool> include = () => jsonWriter.CurrentDepth <= Settings.MaxDepth;
                        var resolver = new JsonNetContractResolver(include);
                        this.Settings.ContractResolver = resolver;
                        var serializer = JsonSerializer.Create(this.Settings);
                        serializer.Serialize(jsonWriter, Data);
                    }
                    response.Write(sw.ToString());
                }
                else
                {
                    scriptSerializer.Serialize(sw, this.Data);
                    response.Write(sw.ToString());
                }
            }
        }
    }

    public class JsonNetTextWriter : JsonTextWriter
    {
        public JsonNetTextWriter(TextWriter textWriter) : base(textWriter) { }

        public int CurrentDepth { get; private set; }

        public override void WriteStartObject()
        {
            CurrentDepth++;
            base.WriteStartObject();
        }

        public override void WriteEndObject()
        {
            CurrentDepth--;
            base.WriteEndObject();
        }
    }

    public class JsonNetContractResolver : DefaultContractResolver
    {
        private readonly Func<bool> _includeProperty;

        public JsonNetContractResolver(Func<bool> includeProperty)
        {
            _includeProperty = includeProperty;
        }

        protected override JsonProperty CreateProperty(
            MemberInfo member, MemberSerialization memberSerialization)
        {
            var property = base.CreateProperty(member, memberSerialization);
            var shouldSerialize = property.ShouldSerialize;
            property.ShouldSerialize = obj => _includeProperty() &&
                                              (shouldSerialize == null ||
                                               shouldSerialize(obj));
            return property;
        }
    }
}

// instantiating JsonNetResult to handle circular reference issue.
var result = new JsonNetResult
{
    Data = <<The results to be returned>>,
    JsonRequestBehavior = JsonRequestBehavior.AllowGet,
    Settings =
        {
            ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
            MaxDepth = 1
        }
};

return result;

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Linq;

namespace customserialization
{
    /// <summary>
    /// IValueProvider personalizado  para manejar max depth level
    /// </summary>
    public class CustomDynamicValueProvider : DynamicValueProvider, IValueProvider
    {
        MemberInfo _memberInfo;
        MaxDepthHandler _levelHandler;

        public CustomDynamicValueProvider(MemberInfo memberInfo, MaxDepthHandler levelHandler) : base(memberInfo)
        {
            _memberInfo = memberInfo;
            _levelHandler = levelHandler;
        }

        public new object GetValue(object target)
        {
            //Si el valor a serializar es un objeto se incrementa el nivel de profundidad. En el caso de las listas el nivel se incrementa en el evento OnSerializing
            if (((PropertyInfo)_memberInfo).PropertyType.IsClass) this._levelHandler.IncrementLevel();

            var rv = base.GetValue(target);

            //Al finalizar la obtención del valor se decrementa. En el caso de las listas el nivel se decrementa en el evento OnSerialized
            if (((PropertyInfo)_memberInfo).PropertyType.IsClass) this._levelHandler.DecrementLevel();

            return rv;
        }
    }

    /// <summary>
    /// Maneja los niveles de serialización
    /// </summary>
    public class MaxDepthHandler
    {
        int _maxDepth;
        int _currentDepthLevel;

        /// <summary>
        /// Nivel actual
        /// </summary>
        public int CurrentDepthLevel { get { return _currentDepthLevel; } }

        public MaxDepthHandler(int maxDepth)
        {
            this._currentDepthLevel = 1;
            this._maxDepth = maxDepth;
        }

        /// <summary>
        /// Incrementa el nivel actual
        /// </summary>
        public void IncrementLevel()
        {
            this._currentDepthLevel++;
        }

        /// <summary>
        /// Decrementa el nivel actual
        /// </summary>
        public void DecrementLevel()
        {
            this._currentDepthLevel--;
        }

        /// <summary>
        /// Determina si se alcanzó el nivel actual
        /// </summary>
        /// <returns></returns>
        public bool IsMaxDepthLevel()
        {
            return !(this._currentDepthLevel < this._maxDepth);
        }
    }

    public class ShouldSerializeContractResolver : DefaultContractResolver
    {

        MaxDepthHandler _levelHandler;

        public ShouldSerializeContractResolver(int maxDepth)
        {
            this._levelHandler = new MaxDepthHandler(maxDepth);
        }


        void OnSerializing(object o, System.Runtime.Serialization.StreamingContext context)
        {
            //Antes de serializar una lista se incrementa el nivel. En el caso de los objetos el nivel se incrementa en el método GetValue del IValueProvider
            if (o.GetType().IsGenericList())
                _levelHandler.IncrementLevel();
        }

        void OnSerialized(object o, System.Runtime.Serialization.StreamingContext context)
        {
            //Despues de serializar una lista se decrementa el nivel. En el caso de los objetos el nivel se decrementa en el método GetValue del IValueProvider
            if (o.GetType().IsGenericList())
                _levelHandler.DecrementLevel();
        }

        protected override JsonContract CreateContract(Type objectType)
        {
            var contract = base.CreateContract(objectType);
            contract.OnSerializingCallbacks.Add(new SerializationCallback(OnSerializing));
            contract.OnSerializedCallbacks.Add(new SerializationCallback(OnSerialized));

            return contract;
        }


        protected override IValueProvider CreateMemberValueProvider(MemberInfo member)
        {
            var rv = base.CreateMemberValueProvider(member);

            if (rv is DynamicValueProvider) //DynamicValueProvider es el valueProvider usado en general
            {
                //Utilizo mi propio ValueProvider, que utilizar el levelHandler
                rv = new CustomDynamicValueProvider(member, this._levelHandler);
            }

            return rv;
        }

        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
        {
            JsonProperty property = base.CreateProperty(member, memberSerialization);

            var isObjectOrList = ((PropertyInfo)member).PropertyType.IsGenericList() || ((PropertyInfo)member).PropertyType.IsClass;



            property.ShouldSerialize =
                    instance =>
                    {
                        var shouldSerialize = true;
                        //Si se alcanzo el nivel maximo y la propiedad (member) actual a serializar es un objeto o lista no se serializa (shouldSerialize = false)
                        if (_levelHandler.IsMaxDepthLevel() && isObjectOrList)
                            shouldSerialize = false;                        

                        return shouldSerialize;
                    };

            return property;
        }



    }

    public static class Util
    {
        public static bool IsGenericList(this Type type)
        {
            foreach (Type @interface in type.GetInterfaces())
            {
                if (@interface.IsGenericType)
                {
                    if (@interface.GetGenericTypeDefinition() == typeof(ICollection<>))
                    {
                        // if needed, you can also return the type used as generic argument
                        return true;
                    }
                }
            }
            return false;
        }
    }
}

        [HttpGet]
        public IActionResult TestJSON()
        {
            var obj = new Thing
            {
                id = 1,
                reference = new Thing
                {
                    id = 2,
                    reference = new Thing
                    {
                        id = 3,
                        reference = new Thing
                        {
                            id = 4
                        }
                    }
                }
            };
            var settings = new JsonSerializerSettings()
            {
                ContractResolver = new ShouldSerializeContractResolver(2),
            };

            return new JsonResult(obj, settings);

        }