如何递归调用 WriteJson？
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【中文标题】如何递归调用 WriteJson？【英文标题】：How do I invoke WriteJson recursively? 【发布时间】：2012-09-15 06:16:58 【问题描述】：我使用 Json.Net。
当我序列化一个Department2 对象并调用WriteJson() 时，我希望它与每个Telephone2 对象一起递归调用，就像我在ReadJson() 中所做的那样。
我该怎么做？
using System;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
public interface ISimpleDatabag
string Databag get; set;
[JsonConverter(typeof(JsonDataBagCreationConverter<Department2>))]
public class Department2
public Telephone2[] Phones get; set;
[JsonConverter(typeof(JsonDataBagCreationConverter<Telephone2>))]
public class Telephone2
public string Name get; set;
public string AreaCode get; set;
public string Number get; set;
public class JsonDataBagCreationConverter<T> : JsonConverter where T : new()
// Json.Net version 4.5.7.15008
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
// When I serialize Department and this function is invoked
// I want it to recursively invoke WriteJson with each of the Telephone objects
// Like I do in ReadJson
// How do I do that?
T t = (T)value;
serializer.Serialize(writer, t.GetType());
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
var jsonObject = JObject.Load(reader);
var target = Create(objectType, jsonObject);
serializer.Populate(jsonObject.CreateReader(), target); // Will call this function recursively for any objects that have JsonDataBagCreationConverter as attribute
return target;
protected T Create(Type objectType, JObject jsonObject)
return new T();
public override bool CanConvert(Type objectType)
return typeof(T).IsAssignableFrom(objectType);
private void Form1_Load(object sender, EventArgs e)
string jsonInput = "\"Name\": \"Seek4\" , \"CustomDepartmentData\": \"This is custom department data\", \"Phones\":[ \"Name\": \"A\", \"AreaCode\":444, \"Number\":11111111 ,\"Name\": \"B\", \"AreaCode\":555, \"Number\":987987987, \"Name\": \"C\", \"AreaCode\":222, \"Number\":123123123, \"CustomPhoneData\": \"This is custom phone data\" ] ";
Department2 objDepartment2 = JsonConvert.DeserializeObject<Department2>(jsonInput); // Yes, it works well
Array.Reverse(objDepartment2.Phones);
string jsonNoDatabag = JsonConvert.SerializeObject(objDepartment2);
【问题讨论】：
【参考方案1】：我最终自己控制了整个过程，使用了这个巨大的（未重构的）函数。 我基本上调查了要序列化的对象的每个属性，然后逐个属性地对其进行序列化。 然后我可以对每个属性进行自定义操作
/// <summary>
/// Serializes an object by merging its current values into its databag and returns the databag
/// </summary>
/// <param name="objectToSerialize"></param>
/// <returns>the current values merged into the original databag</returns>
/// <remarks>Jan Nielsen, 01-10-2012</remarks>
internal static string SerializeObjectToDatabag(object objectToSerialize)
// You have to do it property by property instead of just serializing the entire object and merge it into the original
// because the object might contain lists of objects with custom data and these list might have been sorted differently from when they were loaded
// So you cannot merge them properly unless you do it on a per listitem basis.
// Which is what I do here.
try
if (objectToSerialize == null) // If you ie serialize an empty object in an array
return null;
string updatedDatabag = "";
bool isIDataBag = objectToSerialize is IDataBag;
if (isIDataBag)
updatedDatabag = ((IDataBag)objectToSerialize).Data == null ? "" : ((IDataBag)objectToSerialize).Data.ToString();
// updatedDatabag = ((IDataBag)objectToSerialize).Data.ToString(); // Save original data in a local variable. This is the one we will merge new values into
string result = "";
// Now iterate through the objects properties
// Possible properties:
// Simple types: string, int, bool etc: their current value should be overwritten in the databag
// types that implement IDatabag: they should be sent to this function recursively so their possible customdata is not overwritten
// but instead their simple values are merged into their own databag. Then the result of this single property merge is overwritten in the outer objects databag
// Types that are not simple and don't implement IDatabag but have properties that implement IDatabag
// types that are not simple and don't implement IDatabag and don't have any properties in any depth that implement IDatabag: They are overwritten in the databag
// Types that are arrays:
// If the types in the array are simple types (string, bool etc) the entire array property is overwritten in the databag
// If the types in the array implement IDatabag each object is sent recursively to this function and their databag is updated via merge
// Then the entire array is overwritten in the outer objects databag
// Types that are generic list are treated like arrays
var properties = objectToSerialize.GetType().GetProperties();
// In order to be able to deserialize abstract classes and interfaces, we need to serialize the classname with the class
// the deserializer recognizes the word $type followed by a type, when its is invoked with a serializerSettings of
// serializerSettings.TypeNameHandling = TypeNameHandling.Objects;
string name = objectToSerialize.GetType().AssemblyQualifiedName;
string shortName = RemoveAssemblyDetails(name);
bool addedType = false;
foreach (var propertyInfo in properties)
if (propertyInfo.Name.ToLower() != "data") // Just skip Databag. Databag is not a "real" property but the contents of all the properties when the object was loaded + possible custom data
if (!addedType)
string jsonSingleProperty = " " + ToCustomJson("$type") + " : " + ToCustomJson(shortName) + " ";
// Merge the current value (jsonSingleProperty) into the databag (that might already have been updated with the values of other properties)
// and update the current result with the new values. Ie "Name" : "Seek4" is updated to "Name" : "Seek4Cars" in the databag
// and the function will now use the updated databag to merge the other properties into
updatedDatabag = MergeDefault(jsonSingleProperty, updatedDatabag, true);
addedType = true;
// propertyInfo.Name.ToLower().Contains("struct")
var value = propertyInfo.GetValue(objectToSerialize, null); // This gets the value of the specified property in the current object
isIDataBag = value is IDataBag; // Update for the current object. Note that ie an array of IDatabag will return false here, because array is not IsimpleDatabag
// Basically we should just check if the property implements IDatabag
// But the simpletype check is faster because I don't have to check for the interfaces on ie a string, int etc.
// This branch takes care of 3 cases:
// 1) it is a simple type, ie int
// 2) value is null
// 3) it is an array with a value of null
// If an array with values enters this branch of code the values of the array will be appended, overwritten
// Therefore arrays are treated below in a special case. Unless they are null
// GeneralFunctions.IsExtendedSimpleType_AllTypes(propertyInfo.PropertyType) returns true on ie string[], but only arrays with a value of null should be handled here
// This first check originally just checked for simple types
// Then it became extended simple types ie non-simple types that only contains simple types ie List<int,int>
// But not arrays that must be handled separately
// Then it also handled null values
// And then a special case was made for arrays that are null
if ((GeneralFunctions.IsExtendedSimpleType_AllTypes(propertyInfo.PropertyType) || value == null) && (!propertyInfo.PropertyType.IsArray || (propertyInfo.PropertyType.IsArray && value == null)))
// You have to merge even though it is default value.
// If you have ie a bool that has an initial value of true and you deliberately sets it to false
// You want the defaultvalue of false to be merged into the json.
string jsonSingleProperty = "" + ToCustomJson(propertyInfo.Name) + " : " + ToCustomJson(value) + ""; // ie "Name" : "Seek4Cars"
// Merge the current value (jsonSingleProperty) into the databag (that might already have been updated with the values of other properties)
// and update the current result with the new values. Ie "Name" : "Seek4" is updated to "Name" : "Seek4Cars" in the databag
// and the function will now use the updated databag to merge the other properties into
updatedDatabag = MergeDefault(jsonSingleProperty, updatedDatabag, true);
continue;
if (isIDataBag) // ie PhoneSingle. A single property of type IDataBag
// Invoke recursively
// First check if this is an object with all null values
bool allPropertiesAreNull = true; // Maybe this should in the future be expanded with a check on if the property has its default value ie an int property with a value of 0
foreach (var propertyInfoLocal in value.GetType().GetProperties())
var valueLocal = propertyInfoLocal.GetValue(value, null);
if (valueLocal != null)
allPropertiesAreNull = false;
break;
var testjson = "";
if (allPropertiesAreNull)
result = "" + ToCustomJson(propertyInfo.Name) + " : " + " ";
else
testjson = ToCustomJson(value);
result = "" + ToCustomJson(propertyInfo.Name) + " : " + SerializeObjectToDatabag(value) + "";
updatedDatabag = MergeDefault(result, updatedDatabag, true);
continue;
bool containsIDataBag = CheckForDatabagInterfaces.ImplementsInterface(propertyInfo.PropertyType, "idatabag"); // Check if anything inside the property implements IDatabag ie an array of IDatabag
if (containsIDataBag)
// Check if it is somekind of generic list (List<T>, Dictionary<T,T) etc) and if it is a type of ignoreTypes ie List<entity>)
if (value.GetType().IsGenericType && value.GetType().GetGenericArguments().Length > 0)
string listValuesAsJson = "";
if (value is IEnumerable)
listValuesAsJson += " " + ToCustomJson(propertyInfo.Name) + " : [";
bool containsItems = false;
foreach (var element in (IEnumerable)value)
containsItems = true;
var current = SerializeObjectToDatabag(element);
if (current != null) // If you serialize an empty array element it is null
listValuesAsJson += current + ", "; // Add , between each element
if (containsItems)
listValuesAsJson = listValuesAsJson.Substring(0, listValuesAsJson.Length - 2) + "] "; // remove last , and add ending ] for the array and add a because this property is flowing in the free
else // No items in value
listValuesAsJson += "] "; // add ending ] for the array and add a because this property is flowing in the free
else // A single, generic KeyValuePair property
listValuesAsJson += " " + ToCustomJson(propertyInfo.Name) + " : ";
listValuesAsJson += SerializeObjectToDatabag(value);
listValuesAsJson += " ";
updatedDatabag = MergeDefault(listValuesAsJson, updatedDatabag, false);
else if (value.GetType().IsArray)
string arrayValuesAsJson = " " + ToCustomJson(propertyInfo.Name) + " : [";
bool containsItems = false;
foreach (var element in (Array)value)
// Treat them the same way you treat any other object
var current = SerializeObjectToDatabag(element);
if (current != null) // If you serialize an empty array element it is null
containsItems = true;
arrayValuesAsJson += current + ", ";
if (containsItems)
arrayValuesAsJson = arrayValuesAsJson.Substring(0, arrayValuesAsJson.Length - 2) + "] "; // remove last , and add ending ] for the array and add a because this property is flowing in the free
else // No items in value
arrayValuesAsJson += "] "; // add ending ] for the array and add a because this property is flowing in the free
updatedDatabag = MergeDefault(arrayValuesAsJson, updatedDatabag, false);
else if ( value.GetType().BaseType != null && value.GetType().BaseType.FullName.ToLower().Contains("system.collections.objectmodel"))
// This branch was made specifically to take care of the Media collection of a Seek4.Entities.V2.Media.MediaCollection
var genericList = (IList)value;
int counter = genericList.Count;
string listAsJson = " " + ToCustomJson(propertyInfo.Name) + " : [";
if (counter == 0)
listAsJson += "] "; // Ie "Media": []
else
foreach (var obj in genericList)
var current = SerializeObjectToDatabag(obj);
listAsJson += current + ", ";
listAsJson = listAsJson.Substring(0, listAsJson.Length -2) + " ] " ;
updatedDatabag = MergeDefault(listAsJson, updatedDatabag, true); // hvordan gør json.net dette med standard?
else // a single Non-IDatabag property that contains Idatabag properties
string tempResult = " " + ToCustomJson(propertyInfo.Name) + " : ";
tempResult += SerializeObjectToDatabag(value) + " ";
updatedDatabag = MergeDefault(tempResult, updatedDatabag, true);
else
if (value.GetType().IsArray) // This is an array of simple types so just overwrite
string arrayAsJson = " " + ToCustomJson(propertyInfo.Name) + " : ";
arrayAsJson += ToCustomJson(value) + "";
updatedDatabag = MergeDefault(arrayAsJson, updatedDatabag, false);
else // ie an object that is not simpledatabag and doesn't contain simple databag
string jsonSingleProperty = "" + ToCustomJson(propertyInfo.Name) + " : " + ToCustomJson(value) + "";
updatedDatabag = MergeDefault(jsonSingleProperty, updatedDatabag, true);
return updatedDatabag;
catch (Exception ex)
string message = ex.Message;
string stack = ex.StackTrace;
throw;
internal static string ToCustomJson(object objectToConvertToJson)
try
// Distinguished from Mongodb.Bson.ToJson() extensionmethod by Custom name
JsonSerializerSettings serializerSettings = new JsonSerializerSettings();
serializerSettings.TypeNameHandling = TypeNameHandling.Objects; // Adds a $type on all objects which we need when it is abstract classes and interfaces
IgnoreDataMemberContractResolver contractResolver = new IgnoreDataMemberContractResolver(null, true, true);
serializerSettings.ContractResolver = contractResolver;
serializerSettings.DefaultValueHandling = DefaultValueHandling.Ignore;
IsoDateTimeConverter converter = new IsoDateTimeConverter();
serializerSettings.Converters.Add(converter);
string result = JsonConvert.SerializeObject(objectToConvertToJson, Formatting.None, serializerSettings);
return result;
catch (Exception ex)
throw new Exception("Error in ToCustomJson: " + ex.Message, ex);
【讨论】：
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