53

我需要将复杂的 JSON blob 反序列化为标准 .NET 容器,以便在不知道 JSON 的代码中使用。它期望事物采用标准的 .NET 类型,特别是“对象”可以是原始的或递归的(字典或列表)Dictionary<string, object>List<object>

我不能使用静态类型来映射结果并且 JObject/JToken 不适合。理想情况下,会有某种方法(也许通过合同?)将原始 JSON 转换为基本的 .NET 容器。

我一直在寻找任何方法来诱使 JSON.NET 反序列化器在遇到“{}”或“[]”时创建这些简单类型,但收效甚微。

任何帮助表示赞赏!

4

5 回答 5

70

如果您只想要一个可以处理任意 JSON 并将其转换为常规 .NET 类型(原语、列表和字典)的嵌套结构的通用方法,您可以使用 JSON.Net 的LINQ-to-JSON API来实现:

using System.Linq;
using Newtonsoft.Json.Linq;

public static class JsonHelper
{
    public static object Deserialize(string json)
    {
        return ToObject(JToken.Parse(json));
    }

    public static object ToObject(JToken token)
    {
        switch (token.Type)
        {
            case JTokenType.Object:
                return token.Children<JProperty>()
                            .ToDictionary(prop => prop.Name,
                                          prop => ToObject(prop.Value));

            case JTokenType.Array:
                return token.Select(ToObject).ToList();

            default:
                return ((JValue)token).Value;
        }
    }
}

您可以调用如下所示的方法。 obj将包含Dictionary<string, object>List<object>或原语,具体取决于您开始使用的 JSON。

object obj = JsonHelper.Deserialize(jsonString);
于 2013-10-02T15:15:21.780 回答
18

使用 JSON.NET 将 json 字符串递归反序列化为字典和列表的一种方法是创建一个自定义 json 转换器类,该类派生自JsonConverterJSON.NET 提供的抽象类。

它是在您的派生JsonConverter中放置对象应如何写入和从 json 写入的实现。

您可以JsonConverter像这样使用您的自定义:

var o = JsonConvert.DeserializeObject<IDictionary<string, object>>(json, new DictionaryConverter());

这是我过去成功使用的自定义 JsonConverter 来实现与您在问题中概述的相同目标:

public class DictionaryConverter : JsonConverter {
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) { this.WriteValue(writer, value); }

    private void WriteValue(JsonWriter writer, object value) {
        var t = JToken.FromObject(value);
        switch (t.Type) {
            case JTokenType.Object:
                this.WriteObject(writer, value);
                break;
            case JTokenType.Array:
                this.WriteArray(writer, value);
                break;
            default:
                writer.WriteValue(value);
                break;
        }
    }

    private void WriteObject(JsonWriter writer, object value) {
        writer.WriteStartObject();
        var obj = value as IDictionary<string, object>;
        foreach (var kvp in obj) {
            writer.WritePropertyName(kvp.Key);
            this.WriteValue(writer, kvp.Value);
        }
        writer.WriteEndObject();
    }

    private void WriteArray(JsonWriter writer, object value) {
        writer.WriteStartArray();
        var array = value as IEnumerable<object>;
        foreach (var o in array) {
            this.WriteValue(writer, o);
        }
        writer.WriteEndArray();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) {
        return ReadValue(reader);
    }

    private object ReadValue(JsonReader reader) {
        while (reader.TokenType == JsonToken.Comment) {
            if (!reader.Read()) throw new JsonSerializationException("Unexpected Token when converting IDictionary<string, object>");
        }

        switch (reader.TokenType) {
            case JsonToken.StartObject:
                return ReadObject(reader);
            case JsonToken.StartArray:
                return this.ReadArray(reader);
            case JsonToken.Integer:
            case JsonToken.Float:
            case JsonToken.String:
            case JsonToken.Boolean:
            case JsonToken.Undefined:
            case JsonToken.Null:
            case JsonToken.Date:
            case JsonToken.Bytes:
                return reader.Value;
            default:
                throw new JsonSerializationException
                    (string.Format("Unexpected token when converting IDictionary<string, object>: {0}", reader.TokenType));
        }
    }

    private object ReadArray(JsonReader reader) {
        IList<object> list = new List<object>();

        while (reader.Read()) {
            switch (reader.TokenType) {
                case JsonToken.Comment:
                    break;
                default:
                    var v = ReadValue(reader);

                    list.Add(v);
                    break;
                case JsonToken.EndArray:
                    return list;
            }
        }

        throw new JsonSerializationException("Unexpected end when reading IDictionary<string, object>");
    }

    private object ReadObject(JsonReader reader) {
        var obj = new Dictionary<string, object>();

        while (reader.Read()) {
            switch (reader.TokenType) {
                case JsonToken.PropertyName:
                    var propertyName = reader.Value.ToString();

                    if (!reader.Read()) {
                        throw new JsonSerializationException("Unexpected end when reading IDictionary<string, object>");
                    }

                    var v = ReadValue(reader);

                    obj[propertyName] = v;
                    break;
                case JsonToken.Comment:
                    break;
                case JsonToken.EndObject:
                    return obj;
            }
        }

        throw new JsonSerializationException("Unexpected end when reading IDictionary<string, object>");
    }

    public override bool CanConvert(Type objectType) { return typeof(IDictionary<string, object>).IsAssignableFrom(objectType); }
}

这是 中的等价物f#

type IDictionaryConverter() =
    inherit JsonConverter()

    let rec writeValue (writer: JsonWriter) (value: obj) =
            let t = JToken.FromObject(value)
            match t.Type with
            | JTokenType.Object -> writeObject writer value
            | JTokenType.Array -> writeArray writer value
            | _ -> writer.WriteValue value    

    and writeObject (writer: JsonWriter) (value: obj) =
        writer.WriteStartObject ()
        let obj = value :?> IDictionary<string, obj>
        for kvp in obj do
            writer.WritePropertyName kvp.Key
            writeValue writer kvp.Value
        writer.WriteEndObject ()    

    and writeArray (writer: JsonWriter) (value: obj) = 
        writer.WriteStartArray ()
        let array = value :?> IEnumerable<obj>
        for o in array do
            writeValue writer o
        writer.WriteEndArray ()

    let rec readValue (reader: JsonReader) =
        while reader.TokenType = JsonToken.Comment do
            if reader.Read () |> not then raise (JsonSerializationException("Unexpected token when reading object"))

        match reader.TokenType with
        | JsonToken.Integer
        | JsonToken.Float
        | JsonToken.String
        | JsonToken.Boolean
        | JsonToken.Undefined
        | JsonToken.Null
        | JsonToken.Date
        | JsonToken.Bytes -> reader.Value
        | JsonToken.StartObject -> readObject reader Map.empty
        | JsonToken.StartArray -> readArray reader []
        | _ -> raise (JsonSerializationException(sprintf "Unexpected token when reading object: %O" reader.TokenType))


    and readObject (reader: JsonReader) (obj: Map<string, obj>) =
        match reader.Read() with
        | false -> raise (JsonSerializationException("Unexpected end when reading object"))
        | _ -> reader.TokenType |> function
            | JsonToken.Comment -> readObject reader obj
            | JsonToken.PropertyName ->
                let propertyName = reader.Value.ToString ()
                if reader.Read() |> not then raise (JsonSerializationException("Unexpected end when reading object"))
                let value = readValue reader
                readObject reader (obj.Add(propertyName, value))
            | JsonToken.EndObject -> box obj
            | _ -> raise (JsonSerializationException(sprintf "Unexpected token when reading object: %O" reader.TokenType))

    and readArray (reader: JsonReader) (collection: obj list) =
        match reader.Read() with
        | false -> raise (JsonSerializationException("Unexpected end when reading array"))
        | _ -> reader.TokenType |> function
            | JsonToken.Comment -> readArray reader collection
            | JsonToken.EndArray -> box collection
            | _ -> collection @ [readValue reader] |> readArray reader

    override __.CanConvert t = (typeof<IDictionary<string, obj>>).IsAssignableFrom t
    override __.WriteJson (writer:JsonWriter, value: obj, _:JsonSerializer) = writeValue writer value 
    override __.ReadJson (reader:JsonReader, _: Type, _:obj, _:JsonSerializer) = readValue reader
于 2016-06-25T13:30:44.120 回答
1

我喜欢 AutoMapper,似乎认为它解决了很多问题......就像这个......

为什么不让 JSON.NET 将事物转换为它想要的任何东西......并使用AutoMapper将其映射到您真正想要的对象中。

除非性能是最重要的,否则这个额外的步骤应该是值得的,因为它可以降低复杂性和使用您想要的序列化程序的能力。

于 2011-04-05T02:27:10.253 回答
0

您可以使用自定义来完全控制类型的序列化JsonConverterhttp://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_JsonConverter.htm上的文档。

此外,根据这篇博客文章,您需要JArray用于列表和JObject字典。

于 2011-04-05T01:45:25.267 回答
0

你不能按照我的要求去做。至少在经过大量研究后,我无法判断。我不得不编辑 Json.NET 的源代码。

于 2011-04-08T01:33:49.380 回答