JSON .NET不尊重反序列化PreserveReferencesHandling [英] JSON .Net not respecting PreserveReferencesHandling on Deserialization
问题描述
我已经双向链表，我想deserialise列表
I have doubly linked list that I am trying to deserialise.
我的方案密切相关这一SO：的双向链表以JSON
My scenario closely relates to this SO: Doubly Linked List to JSON
我有以下的JSON设置：
I have the following JSON settings:
_jsonSettings = new JsonSerializerSettings()
{
TypeNameHandling = TypeNameHandling.Auto,
ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor,
PreserveReferencesHandling = PreserveReferencesHandling.Objects,
ObjectCreationHandling = ObjectCreationHandling.Auto
};
当我看着序列化输出，它似乎正确的，节点之间的引用适当的代表。
When I look at the serialised output, it appears correct, and the references between nodes are properly represented.
当数据被deserialised，在子对象的父属性为null，即使它们填充了$ REF正确。
When the data is deserialised, the Parent properties in the Child objects are null, even though they are populated with $ref correctly.
下面是JSON（修剪可读性）
Below is a sample of the JSON (trimmed for readability)
在键入这个问题的过程中的一个样本 - 我可能已经看到了麻烦的根源...
In the process of typing this question - I may have seen the source of the trouble...
在儿童数组属性的对象没有$类型的属性。
The objects in the "Children" array property do not have $type attributes.
这可能是因为儿童和家长的属性是通用类型T的
This could be because the Children and Parent properties are of generic type T.
请注意，实际的类型被序列化是一个派生类TemplateDataLinkedListBase的
Note that the actual type being serialised is a derived class of TemplateDataLinkedListBase
public class TemplateDataQueryElement : TemplateDataLinkedListBase<TemplateDataQueryElement>
下面是基类的摘录：
public class TemplateDataLinkedListBase<T> where T : TemplateDataLinkedListBase<T>
{
[JsonProperty(TypeNameHandling = TypeNameHandling.Objects)]
public T Parent { get; set; }
[JsonProperty(TypeNameHandling=TypeNameHandling.Objects)]
public List<T> Children { get; set; }
}
我怎么能deserialise这个JSON以这样的方式父属性？NOT NULL，并包含对父对象的引用
How can I deserialise this JSON in such a way that the Parent property is not null and contains a reference to the parent object?
{
"$id": "9",
"$type": "Contracts.Models.TemplateDataQueryElement, Contracts",
"Query": null,
"Parent": null,
"Children": [
{
"$id": "11",
"Query": null,
"Parent": {
"$ref": "9"
},
"Children": [
{
"$id": "13",
"Query": null,
"Parent": {
"$ref": "11"
},
"Children": [],
"EntityName": "Widgets",
"Fields": [
"Id"
],
"Key": ""
},
下面是Pastebin链接的相关代码：
Here are PasteBin links to the relevant code:
的http：// pastebin.com/i1jxVGG3
http://pastebin.com/T1xqEWW2
的http://pastebin.com/ha42SeF7
的http：//引擎收录.COM / cezwZqx6
http://pastebin.com/uFbTbUZe
的http://pastebin.com/sRhNQgzh
推荐答案
下面是我尝试和工作得很好：
Here is what I tried and worked fine:
的类
public class TemplateDataLinkedListBase<T> where T : TemplateDataLinkedListBase<T>
{
[JsonProperty(TypeNameHandling = TypeNameHandling.Objects)]
public T Parent { get; set; }
[JsonProperty(TypeNameHandling = TypeNameHandling.Objects)]
public List<T> Children { get; set; }
}
public class TemplateDataQueryElement : TemplateDataLinkedListBase<TemplateDataQueryElement>
{
public string Query { get; set; }
public TemplateDataQueryElement()
{
Children = new List<TemplateDataQueryElement>();
}
}
初始化
var childLowest = new TemplateDataQueryElement
{
Query = "Lowest"
};
var childMiddle = new TemplateDataQueryElement
{
Query = "Middle",
Children = new List<TemplateDataQueryElement>
{
childLowest
}
};
childLowest.Parent = childMiddle;
var parent = new TemplateDataQueryElement
{
Query = "Parent",
Children = new List<TemplateDataQueryElement>
{
childMiddle
}
};
childMiddle.Parent = parent;
序列化设置
var _jsonSettings = new JsonSerializerSettings()
{
TypeNameHandling = TypeNameHandling.Auto,
ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor,
PreserveReferencesHandling = PreserveReferencesHandling.Objects,
ObjectCreationHandling = ObjectCreationHandling.Auto
};
连载
var serializedStr = JsonConvert.SerializeObject(parent, Formatting.Indented, _jsonSettings);
序列化的JSON看起来是这样的：
The serialized json looks like this:
{
"$id": "1",
"Query": "Parent",
"Parent": null,
"Children": [
{
"$id": "2",
"Query": "Middle",
"Parent": {
"$ref": "1"
},
"Children": [
{
"$id": "3",
"Query": "Lowest",
"Parent": {
"$ref": "2"
},
"Children": []
}
]
}
]
}
反序列化
var deserializedStructure = JsonConvert.DeserializeObject<TemplateDataQueryElement>(serializedStr, _jsonSettings);
在 deserializedStructure 正确保存的参考
演示
https：//开头dotnetfiddle。净/ j1Qhu6
更新1
原因我的榜样工作正常，你在其他链接发布的代码不会是因为我的类包含默认构造函数，而你没有。分析你的类，添加一个默认的构造他们，也不会断裂的功能和反序列化将是成功的正确初始化父属性。所以你基本上需要做的就是添加一个默认的构造函数来两个类：
The reason my example works, and the code you posted in the additional links doesn't is because my classes contain default constructor, and yours don't. Analyzing your classes, adding a default constructor to them, it won't break the functionality and the deserialization will be successful with Parent property initialized correctly. So what you basically need to do is add a default constructor to both classes:
public class TemplateDataLinkedListBase<T> where T : TemplateDataLinkedListBase<T>
{
[JsonProperty(TypeNameHandling = TypeNameHandling.Objects)]
public T Parent { get; set; }
[JsonProperty(TypeNameHandling=TypeNameHandling.Objects)]
public List<T> Children { get; set; }
public string EntityName { get; set; }
public HashSet<string> Fields { get; set; }
public string Key { get { return getKey(); } }
public TemplateDataLinkedListBase()
{
Children = new List<T>();
Fields = new HashSet<string>();
}
public TemplateDataLinkedListBase(string entityName)
{
EntityName = entityName;
Children = new List<T>();
Fields = new HashSet<string>();
}
private string getKey()
{
List<string> keys = new List<string>();
keys.Add(this.EntityName);
getParentKeys(ref keys, this);
keys.Reverse();
return string.Join(".", keys);
}
private void getParentKeys(ref List<string> keys, TemplateDataLinkedListBase<T> element)
{
if (element.Parent != null)
{
keys.Add(element.Parent.EntityName);
getParentKeys(ref keys, element.Parent);
}
}
public T AddChild(T child)
{
child.Parent = (T)this;
Children.Add(child);
return (T)this;
}
public T AddChildren(List<T> children)
{
foreach (var child in children)
{
child.Parent = (T)this;
}
Children.AddRange(children);
return (T)this;
}
public void AddFields(IEnumerable<string> fields)
{
foreach (var field in fields)
this.Fields.Add(field);
}
public TemplateDataLinkedListBase<T> Find(string searchkey)
{
if (this.Key == searchkey)
{
return this;
}
else
{
foreach (var child in Children)
{
if (child.Key == searchkey)
{
return child;
}
else
{
var childResult = child.Find(searchkey);
if (childResult != null) return childResult;
}
}
}
return null;
}
}
public class TemplateDataQueryElement : TemplateDataLinkedListBase<TemplateDataQueryElement>, ITemplateDataQueryElement
{
public string TemplateModelName { get; set; }
public string RecordId { get; set; }
public string ParentForeignKeyName { get; set; }
public string Query { get; set; }
public dynamic ObjectData { get; set; }
public ITemplateDataParseResult ParseResult { get; set; }
public TemplateDataQueryElement() : base()
{
Fields.Add("Id"); //Always retrieve Id's
ObjectData = new ExpandoObject();
}
public TemplateDataQueryElement(string entityName)
: base(entityName)
{
Fields.Add("Id"); //Always retrieve Id's
ObjectData = new ExpandoObject();
}
public override string ToString()
{
return string.Format("{0}: {1}", EntityName, Query);
}
}
的
实体名称，你通过你的构造函数中设置属性，将正确反序列化，因为它是一个公共属性。
The EntityName property which you set through your constructor, will be deserialized correctly, since it is a public property.
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