如何在同一对象中使用重复的属性名称反序列化JSON [英] How to deserialize JSON with duplicate property names in the same object
问题描述
我有一个JSON字符串,我希望它包含无法使JSON.NET满意的重复键.
I have a JSON string that I expect to contain duplicate keys that I am unable to make JSON.NET happy with.
我想知道是否有人知道最好的方式(也许使用JsonConverter
?)来获取JSON.NET,以便在看到重复的键名时将JObject
的子级JObjects
更改为JArrays
? /p>
I was wondering if anybody knows the best way (maybe using JsonConverter
? ) to get JSON.NET to change a JObject
's child JObjects
into to JArrays
when it sees duplicate key names ?
// For example: This gives me a JObject with a single "JProperty\JObject" child.
var obj = JsonConvert.DeserializeObject<object>("{ \"HiThere\":1}");
// This throws:
// System.ArgumentException : Can not add Newtonsoft.Json.Linq.JValue to Newtonsoft.Json.Linq.JObject.
obj = JsonConvert.DeserializeObject<object>("{ \"HiThere\":1, \"HiThere\":2, \"HiThere\":3 }");
我要反序列化的实际JSON更加复杂,重复项嵌套在多个级别.但是上面的代码演示了为什么它对我失败.
The actual JSON I am trying to deserialize is much more complicated and the duplicates are nested at multiple levels. But the code above demonstrates why it fails for me.
我了解JSON不正确,这就是为什么我要问JSON.NET是否有解决此问题的方法的原因.为了论证,假设我无法控制JSON.实际上,我确实为父对象使用了特定类型,但是遇到麻烦的特定属性将是字符串或另一个嵌套的JSON对象.由于这个原因,失败的属性类型是对象".
I understand that the JSON is not correct which is why I am asking if JSON.NET has a way to work around this. For argument's sake let's say I do not have control over the JSON. I actually do use a specific type for the parent object but the particular property that is having trouble will either be a string or another nested JSON object. The failing property type is "object" for this reason.
推荐答案
有趣的问题.我玩了一段时间,发现虽然JObject
不能包含具有重复名称的属性,但是在反序列化期间用于填充它的JsonTextReader
并没有这样的限制. (如果您考虑一下,这是有道理的:它是仅向前的阅读器;它与过去已阅读的内容无关).掌握了这些知识之后,我开始编写一些代码,这些代码将填充JTokens的层次结构,如果在特定的JObject中遇到重复的属性名称,则可以根据需要将属性值转换为JArrays.由于我不知道您的实际JSON和要求,因此您可能需要对其进行一些调整,但这至少是要从头开始的.
Interesting question. I played around with this for a while and discovered that while a JObject
cannot contain properties with duplicate names, the JsonTextReader
used to populate it during deserialization does not have such a restriction. (This makes sense if you think about it: it's a forward-only reader; it is not concerned with what it has read in the past). Armed with this knowledge, I took a shot at writing some code that will populate a hierarchy of JTokens, converting property values to JArrays as necessary if a duplicate property name is encountered in a particular JObject. Since I don't know your actual JSON and requirements, you may need to make some adjustments to it, but it's something to start with at least.
代码如下:
public static JToken DeserializeAndCombineDuplicates(JsonTextReader reader)
{
if (reader.TokenType == JsonToken.None)
{
reader.Read();
}
if (reader.TokenType == JsonToken.StartObject)
{
reader.Read();
JObject obj = new JObject();
while (reader.TokenType != JsonToken.EndObject)
{
string propName = (string)reader.Value;
reader.Read();
JToken newValue = DeserializeAndCombineDuplicates(reader);
JToken existingValue = obj[propName];
if (existingValue == null)
{
obj.Add(new JProperty(propName, newValue));
}
else if (existingValue.Type == JTokenType.Array)
{
CombineWithArray((JArray)existingValue, newValue);
}
else // Convert existing non-array property value to an array
{
JProperty prop = (JProperty)existingValue.Parent;
JArray array = new JArray();
prop.Value = array;
array.Add(existingValue);
CombineWithArray(array, newValue);
}
reader.Read();
}
return obj;
}
if (reader.TokenType == JsonToken.StartArray)
{
reader.Read();
JArray array = new JArray();
while (reader.TokenType != JsonToken.EndArray)
{
array.Add(DeserializeAndCombineDuplicates(reader));
reader.Read();
}
return array;
}
return new JValue(reader.Value);
}
private static void CombineWithArray(JArray array, JToken value)
{
if (value.Type == JTokenType.Array)
{
foreach (JToken child in value.Children())
array.Add(child);
}
else
{
array.Add(value);
}
}
这是一个演示:
class Program
{
static void Main(string[] args)
{
string json = @"
{
""Foo"" : 1,
""Foo"" : [2],
""Foo"" : [3, 4],
""Bar"" : { ""X"" : [ ""A"", ""B"" ] },
""Bar"" : { ""X"" : ""C"", ""X"" : ""D"" },
}";
using (StringReader sr = new StringReader(json))
using (JsonTextReader reader = new JsonTextReader(sr))
{
JToken token = DeserializeAndCombineDuplicates(reader);
Dump(token, "");
}
}
private static void Dump(JToken token, string indent)
{
Console.Write(indent);
if (token == null)
{
Console.WriteLine("null");
return;
}
Console.Write(token.Type);
if (token is JProperty)
Console.Write(" (name=" + ((JProperty)token).Name + ")");
else if (token is JValue)
Console.Write(" (value=" + token.ToString() + ")");
Console.WriteLine();
if (token.HasValues)
foreach (JToken child in token.Children())
Dump(child, indent + " ");
}
}
输出:
Object
Property (name=Foo)
Array
Integer (value=1)
Integer (value=2)
Integer (value=3)
Integer (value=4)
Property (name=Bar)
Array
Object
Property (name=X)
Array
String (value=A)
String (value=B)
Object
Property (name=X)
Array
String (value=C)
String (value=D)
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