Flurl GetJsonAsync反序列化Cosmos SDK JSON失败求助

核心问题点 #

1. 反序列化接口报错：直接用GetJsonAsync<IAccount>()报错，是因为JSON序列化器无法实例化接口/抽象类，这是序列化的基本规则。
2. 反序列化BaseAccount返回空值：原因有三个：
   • JSON最外层包了account节点，而你直接把BaseAccount作为根对象反序列化，字段完全不匹配
   • BaseAccount的Type属性标注的JsonProperty是type，但JSON里对应的字段是@type，映射失败
   • JSON中account_number和sequence是字符串类型，而代码里定义的是ulong，类型不兼容导致反序列化失败

具体修复步骤 #

1. 定义JSON根对象类 #

先创建对应整个JSON结构的根类，匹配外层的account节点：

public class AccountResponse
{
    [JsonProperty(PropertyName = "account")]
    public BaseAccount Account { get; set; } = null!;
}

2. 修正BaseAccount的字段映射与类型转换 #

调整字段的JsonProperty匹配JSON，同时处理字符串转ulong的问题：

public class BaseAccount : IAccount
{
    public BaseAccount()
    {
    }
    public BaseAccount(string type, string address, PublicKey publicKey, ulong accountNumber, ulong sequence)
    {
        Type = type;
        Address = address;
        PublicKey = publicKey;
        AccountNumber = accountNumber;
        Sequence = sequence;
    }

    // 修正为@type，匹配JSON中的字段名
    [JsonProperty(PropertyName = "@type")]
    public string Type { get; set; } = null!;

    // 用转换器处理字符串转ulong
    [JsonProperty(PropertyName = "account_number")]
    [JsonConverter(typeof(StringToUlongConverter))]
    public ulong AccountNumber { get; set; }

    [JsonProperty(PropertyName = "address")]
    public string Address { get; set; } = null!;

    [JsonProperty(PropertyName = "pub_key")]
    public PublicKey PublicKey { get; set; } = null!;

    // 同样用转换器处理sequence字段
    [JsonProperty(PropertyName = "sequence")]
    [JsonConverter(typeof(StringToUlongConverter))]
    public ulong Sequence { get; set; }

    // 接口实现保持原有逻辑
    public PublicKey GetPublicKey()
    {
        return new PublicKey()
        {
            Type = null,
            Key = PublicKey.Key
        };
    }
    public ulong GetSequence() => Sequence;
    public ulong GetAccountNumber() => AccountNumber;
}

3. 实现字符串转ulong的转换器 #

处理JSON中字符串类型的数字到ulong的转换：

public class StringToUlongConverter : JsonConverter<ulong>
{
    public override ulong ReadJson(JsonReader reader, Type objectType, ulong existingValue, bool hasExistingValue, JsonSerializer serializer)
    {
        if (reader.Value is string str)
        {
            ulong.TryParse(str, out var result);
            return result;
        }
        return existingValue;
    }

    public override void WriteJson(JsonWriter writer, ulong value, JsonSerializer serializer)
    {
        writer.WriteValue(value.ToString());
    }
}

4. 定义PublicKey类 #

确保与JSON中的pub_key结构匹配：

public class PublicKey
{
    [JsonProperty(PropertyName = "@type")]
    public string? Type { get; set; }

    [JsonProperty(PropertyName = "key")]
    public string Key { get; set; } = null!;
}

5. 正确执行反序列化 #

现在用根对象类来反序列化，就能拿到完整的Account数据：

var accountResponse = await clientResponse.GetJsonAsync<AccountResponse>();
BaseAccount account = accountResponse.Account;

内容的提问来源于stack exchange，提问作者Adonis Villanueva