.NET中如何用Json.NET序列化name/value数组形式的attributes属性？

在.NET中是否有办法将attributes属性序列化为name/value形式？我无法找到合适的方式将类序列化为包含sport、venue、city、province等字段的attributes属性，期望生成的JSON结构如下：

{"uid": "uuid","object": "live_event","title": "Event Name","event_start": "2022-10-10T12:00:00:000Z","timezone": "America/Denver","external_id": "some_external_user_generated_id","container_uid": "02f8270a-8662-45b3-898a-c915a68cdf87","description": "Description of the event","short_description": "Short description of the event","attributes": [{ "sport": "Soccer" },{ "venue": "New Park" },{ "city": "Calgary" },{ "province": "Alberta" },{ "teams": ["teamA", "teamB"] }]}

现有CreateEventRequest类定义如下：

public class CreateEventRequest : VidFlexRequest, ISaveEventRequest
{
    [JsonProperty("uid", NullValueHandling = NullValueHandling.Ignore)]
    public string UId { get; set; }
    [JsonProperty("title")]
    public string Title { get; set; }
    [JsonProperty("event_start")]
    public string EventStart { get; set; }
    [JsonProperty("timezone")]
    public string TimeZone { get; set; }
    [JsonProperty("external_id")]
    public string ExternalId { get; set; }
    [JsonProperty("description", NullValueHandling = NullValueHandling.Ignore)]
    public string Description { get; set; }
    [JsonProperty("short_description", NullValueHandling = NullValueHandling.Ignore)]
    public string ShortDescription { get; set; }
}

可以通过自定义属性类型+Json.NET序列化特性实现需求，具体步骤如下：

1. 定义单个属性项类型 #

attributes中的每个元素都是单键值对（值可以是字符串或数组），可以用带JsonExtensionData特性的类实现类型安全的动态键处理：

public class AttributeItem
{
    [JsonExtensionData]
    public Dictionary<string, object> Data { get; set; } = new Dictionary<string, object>();

    // 便捷构造函数，快速创建单键值对
    public AttributeItem(string key, object value)
    {
        Data[key] = value;
    }
}

2. 更新CreateEventRequest类 #

补充缺失的字段（object、container_uid），并添加attributes属性：

public class CreateEventRequest : VidFlexRequest, ISaveEventRequest
{
    [JsonProperty("uid", NullValueHandling = NullValueHandling.Ignore)]
    public string UId { get; set; }
    [JsonProperty("title")]
    public string Title { get; set; }
    [JsonProperty("event_start")]
    public string EventStart { get; set; }
    [JsonProperty("timezone")]
    public string TimeZone { get; set; }
    [JsonProperty("external_id")]
    public string ExternalId { get; set; }
    [JsonProperty("description", NullValueHandling = NullValueHandling.Ignore)]
    public string Description { get; set; }
    [JsonProperty("short_description", NullValueHandling = NullValueHandling.Ignore)]
    public string ShortDescription { get; set; }
    
    // 新增attributes属性
    [JsonProperty("attributes")]
    public List<AttributeItem> Attributes { get; set; } = new List<AttributeItem>();
    
    // 补充JSON中要求的固定字段
    [JsonProperty("object")]
    public string ObjectType => "live_event";
    [JsonProperty("container_uid", NullValueHandling = NullValueHandling.Ignore)]
    public string ContainerUid { get; set; }
}

3. 构造实例并序列化 #

创建请求实例，填充属性后用Json.NET序列化：

var request = new CreateEventRequest
{
    UId = "uuid",
    Title = "Event Name",
    EventStart = "2022-10-10T12:00:00:000Z",
    TimeZone = "America/Denver",
    ExternalId = "some_external_user_generated_id",
    ContainerUid = "02f8270a-8662-45b3-898a-c915a68cdf87",
    Description = "Description of the event",
    ShortDescription = "Short description of the event",
    Attributes = new List<AttributeItem>
    {
        new AttributeItem("sport", "Soccer"),
        new AttributeItem("venue", "New Park"),
        new AttributeItem("city", "Calgary"),
        new AttributeItem("province", "Alberta"),
        new AttributeItem("teams", new[] {"teamA", "teamB"})
    }
};

var json = JsonConvert.SerializeObject(request, Formatting.Indented);

4. 简洁替代方案 #

如果不需要类型安全，可直接将Attributes定义为List<Dictionary<string, object>>，省去自定义类步骤：

[JsonProperty("attributes")]
public List<Dictionary<string, object>> Attributes { get; set; } = new List<Dictionary<string, object>>();

构造时直接添加字典：

Attributes = new List<Dictionary<string, object>>
{
    new Dictionary<string, object> { {"sport", "Soccer"} },
    new Dictionary<string, object> { {"venue", "New Park"} },
    new Dictionary<string, object> { {"city", "Calgary"} },
    new Dictionary<string, object> { {"province", "Alberta"} },
    new Dictionary<string, object> { {"teams", new[] {"teamA", "teamB"}} }
};

注意事项 #

• 确保项目已引用Newtonsoft.Json（Json.NET）包，否则JsonProperty等特性无法使用
• 若使用System.Text.Json，需替换为JsonPropertyName特性，序列化逻辑保持一致

内容的提问来源于stack exchange，提问作者Mike Flynn