如何配置Text.Json源生成器参数以反序列化复杂JSON字符串

首先，你的JSON字符串是一个混合类型的数组，包含三个元素：

1. 一个嵌套数组，里面的每个元素是「订单ID为键，订单详情为值」的对象
2. 字符串 "openOrders"
3. 包含sequence字段的对象

你之前的错误在于把整个JSON当成了OpenOrderFrame[]类型的数组，但实际结构完全不匹配，导致反序列化失败。以下是两种正确的实现方式：

方式一：自定义转换器实现强类型映射（推荐） #

1. 定义模型类 #

// 订单详情模型，属性名与JSON字段一一对应
public class OpenOrder
{
    public string Cost { get; set; }
    public string Vol_exec { get; set; }
    public string Fee { get; set; }
    public string Avg_price { get; set; }
}

// 序列号信息模型
public class SequenceData
{
    public int Sequence { get; set; }
}

// 最终的响应模型，对应JSON数组的三个元素
public class OpenOrderResponse
{
    public Dictionary<string, OpenOrder>[] Orders { get; set; }
    public string ChannelName { get; set; }
    public SequenceData SequenceInfo { get; set; }
}

2. 编写自定义转换器 #

将JSON数组转换为OpenOrderResponse对象：

public class OpenOrderResponseConverter : JsonConverter<OpenOrderResponse>
{
    public override OpenOrderResponse Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType != JsonTokenType.StartArray)
            throw new JsonException("JSON结构应为数组");

        // 读取第一个元素：订单数组
        reader.Read();
        var orders = JsonSerializer.Deserialize<Dictionary<string, OpenOrder>[]>(ref reader, options);

        // 读取第二个元素：频道名称字符串
        reader.Read();
        var channelName = reader.GetString();

        // 读取第三个元素：序列号对象
        reader.Read();
        var sequenceInfo = JsonSerializer.Deserialize<SequenceData>(ref reader, options);

        // 确认数组结束
        reader.Read();
        if (reader.TokenType != JsonTokenType.EndArray)
            throw new JsonException("JSON数组未正常结束");

        return new OpenOrderResponse
        {
            Orders = orders,
            ChannelName = channelName,
            SequenceInfo = sequenceInfo
        };
    }

    public override void Write(Utf8JsonWriter writer, OpenOrderResponse value, JsonSerializerOptions options)
    {
        writer.WriteStartArray();
        JsonSerializer.Serialize(writer, value.Orders, options);
        writer.WriteStringValue(value.ChannelName);
        JsonSerializer.Serialize(writer, value.SequenceInfo, options);
        writer.WriteEndArray();
    }
}

3. 配置源生成器上下文 #

[JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)]
[JsonSerializable(typeof(OpenOrderResponse))]
[JsonSerializable(typeof(Dictionary<string, OpenOrder>[]))]
[JsonSerializable(typeof(SequenceData))]
public partial class OpenOrderContext : JsonSerializerContext
{
    static OpenOrderContext()
    {
        // 注册自定义转换器
        Default.Converters.Add(new OpenOrderResponseConverter());
    }
}

4. 反序列化代码 #

var json = @"[[{""OU2CJ3-UBRYG-KCPVS1"":{""cost"":""27187.08000"",""vol_exec"":""3.60000000"",""fee"":""27.18708"",""avg_price"":""7996.20000""}}],""openOrders"",{""sequence"": 59342}]";

var response = JsonSerializer.Deserialize(json, OpenOrderContext.Default.OpenOrderResponse);

方式二：直接处理object数组（快速实现） #

如果不需要强类型模型，可以直接反序列化为object[]，再手动转换每个元素：

1. 配置源生成器上下文 #

[JsonSourceGenerationOptions(PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase)]
[JsonSerializable(typeof(object[]))]
[JsonSerializable(typeof(Dictionary<string, OpenOrder>[]))]
[JsonSerializable(typeof(SequenceData))]
public partial class OpenOrderContext : JsonSerializerContext
{ }

2. 反序列化与转换 #

var json = @"[[{""OU2CJ3-UBRYG-KCPVS1"":{""cost"":""27187.08000"",""vol_exec"":""3.60000000"",""fee"":""27.18708"",""avg_price"":""7996.20000""}}],""openOrders"",{""sequence"": 59342}]";

// 先反序列化为object数组
var rawArray = JsonSerializer.Deserialize<object[]>(json, OpenOrderContext.Default.ObjectArray);

// 逐个转换元素
var orders = JsonSerializer.Deserialize<Dictionary<string, OpenOrder>[]>(
    JsonSerializer.Serialize(rawArray[0]), 
    OpenOrderContext.Default.DictionaryStringOpenOrderArray);
string channelName = (string)rawArray[1];
var sequenceInfo = JsonSerializer.Deserialize<SequenceData>(
    JsonSerializer.Serialize(rawArray[2]), 
    OpenOrderContext.Default.SequenceData);

内容的提问来源于stack exchange，提问作者Guillaume Paris