[英]Cannot Deserialize the Current JSON Object (Empty Array)
我試圖使這個程序將所有這些對象格式化為樹視圖,為此(我使用JSON來排序對象),我需要解析JSON,所以我選擇了JSON.NET。
以下是格式化的示例:
{
"Space": {
"ClassName": "SpaceObject",
"Name": "Space",
"Children": {
"Object1": {
"ClassName": "Object",
"Name": "Object1",
"Children": []
},
"Object2": {
"ClassName": "Object",
"Name": "Object2",
"Children": []
}
}
}
}
public class CObject
{
[JsonProperty(PropertyName = "Name")]
public string Name { get; set; }
[JsonProperty(PropertyName = "ClassName")]
public string ClassName { get; set; }
[JsonProperty(PropertyName = "Children")]
public IDictionary<string, CObject> Children { get; set; }
}
IDictionary<string, CObject> obj = JsonConvert.DeserializeObject<IDictionary<string, CObject>>(Json, new JsonSerializerSettings() {
MissingMemberHandling = MissingMemberHandling.Ignore,
NullValueHandling = NullValueHandling.Ignore,
});
foreach (var i in obj) {
ExplorerView1.Nodes.Add(AddObject(i.Value));
}
我相信我發現了錯誤,這是由於子數組中沒有任何對象。 我不知道如何解決這個問題,任何人都可以幫忙嗎?
JsonSingleOrEmptyArrayConverter<T>
從這個答案來反序列化JSON,當類型可以不同時幾乎JsonSingleOrEmptyArrayConverter<T>
你的需要。 只需要增強它以允許當前的合同類型是字典合同以及對象合同。
首先,修改JsonSingleOrEmptyArrayConverter<T>
,如下所示:
public class JsonSingleOrEmptyArrayConverter<T> : JsonConverter where T : class
{
//https://stackoverflow.com/questions/29449641/deserialize-json-when-type-can-be-different?rq=1
public override bool CanConvert(Type objectType)
{
return typeof(T).IsAssignableFrom(objectType);
}
public override bool CanWrite { get { return false; } }
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var contract = serializer.ContractResolver.ResolveContract(objectType);
// Allow for dictionary contracts as well as objects contracts, since both are represented by
// an unordered set of name/value pairs that begins with { (left brace) and ends with } (right brace).
if (!(contract is Newtonsoft.Json.Serialization.JsonObjectContract
|| contract is Newtonsoft.Json.Serialization.JsonDictionaryContract))
{
throw new JsonSerializationException(string.Format("Unsupported objectType {0} at {1}.", objectType, reader.Path));
}
switch (reader.SkipComments().TokenType)
{
case JsonToken.StartArray:
{
int count = 0;
while (reader.Read())
{
switch (reader.TokenType)
{
case JsonToken.Comment:
break;
case JsonToken.EndArray:
// You might want to allocate an empty object here if existingValue is null
// If so, do
// return existingValue ?? contract.DefaultCreator();
return existingValue;
default:
{
count++;
if (count > 1)
throw new JsonSerializationException(string.Format("Too many objects at path {0}.", reader.Path));
existingValue = existingValue ?? contract.DefaultCreator();
serializer.Populate(reader, existingValue);
}
break;
}
}
// Should not come here.
throw new JsonSerializationException(string.Format("Unclosed array at path {0}.", reader.Path));
}
case JsonToken.Null:
return null;
case JsonToken.StartObject:
existingValue = existingValue ?? contract.DefaultCreator();
serializer.Populate(reader, existingValue);
return existingValue;
default:
throw new InvalidOperationException("Unexpected token type " + reader.TokenType.ToString());
}
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
public static partial class JsonExtensions
{
public static JsonReader SkipComments(this JsonReader reader)
{
while (reader.TokenType == JsonToken.Comment && reader.Read())
;
return reader;
}
}
然后反序列化如下:
var settings = new JsonSerializerSettings
{
MissingMemberHandling = MissingMemberHandling.Ignore,
NullValueHandling = NullValueHandling.Ignore,
Converters = { new JsonSingleOrEmptyArrayConverter<IDictionary<string, CObject>>() },
};
var obj = JsonConvert.DeserializeObject<IDictionary<string, CObject>>(Json, settings);
筆記:
我的假設是只在沒有子節點時才使用空數組[]
。 如果數組是非空的,則此假設將是錯誤的並且轉換器將無法正常工作。
轉換器為空數組返回null
值。 如果您更喜歡空字典,請取消注釋以下行:
// You might want to allocate an empty object here if existingValue is null // If so, do // return existingValue ?? contract.DefaultCreator();
在這里工作.Net小提琴。
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