【问题标题】:How do I invoke WriteJson recursively?如何递归调用 WriteJson?
【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】:

    标签: serialization json.net jsonserializer


    【解决方案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);
            }
        }
    

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