问题
I use Json.Net.
When I serialize a Department2 object and WriteJson() is invoked I want it to be recursively invoked with each of the Telephone2 objects like I do in ReadJson().
How do I do that?
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);
}
回答1:
I ended up controlling the entire process myself, using this huge (not refactored) function. I basically investigate each of the properties of the object to serialize and then serialize it property by property. Then I can do custom things on each property
/// <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);
}
}
来源：https://stackoverflow.com/questions/12554002/how-do-i-invoke-writejson-recursively