C#反序列化GeoJSON文件后Root及Properties对象为空的问题

问题背景 #

有一份GeoJSON文件片段如下：

{"type":"FeatureCollection", "features": [
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[45.882982627281955,35.98144306876872],[45.8830448154499,35.98142063110326],[45.883106013386524,35.98143674855534],[45.883177395327635,35.981590195979166],[45.88306057502328,35.98161790966196],[45.882982627281955,35.98144306876872]]]},"properties":{"Code":1,"Landuse":"fde","Longitude":45.8830793043,"latitude":35.9815185013}},
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[45.88321822952168,35.98143433703011],[45.88329577844585,35.981578778123584],[45.883184747057655,35.98160599975271],[45.883177395327635,35.981590195979166],[45.88313701140243,35.981503383976175],[45.883107851319025,35.981440699498734],[45.88321822952168,35.98143433703011]]]},"properties":{"Code":2,"Landuse":"fde","Longitude":45.8832014571,"latitude":35.9815182472}}
]}

尝试用C#读取并编辑该文件时，因ViewModel结构错误，导致反序列化后Root对象及properties均为空。

错误原因 #

原ViewModel结构与GeoJSON的层级完全不匹配：

• GeoJSON根节点是FeatureCollection，包含features数组，每个元素是Feature对象
• 每个Feature包含单个geometry和单个properties对象，而非List<Properties>
• 原Root类直接包含geometry和List<Properties>，没有对应features数组，导致反序列化无法匹配数据

修正方案 #

重新定义与GeoJSON结构完全对应的ViewModel：

public class Geometry
{
    public string type { get; set; }
    public List<List<List<double>>> coordinates { get; set; }
}

public class Properties
{
    public int Code { get; set; }
    public string Landuse { get; set; }
    public double Longitude { get; set; }
    public double latitude { get; set; }
}

public class Feature
{
    public string type { get; set; }
    public Geometry geometry { get; set; }
    public Properties properties { get; set; }
}

public class Root
{
    public string type { get; set; }
    public List<Feature> features { get; set; }
}

修改后的操作代码 #

调整反序列化和编辑逻辑，遍历features数组找到目标Feature并修改其properties：

string json = File.ReadAllText(myPath);
var deserialize = JsonConvert.DeserializeObject<Root>(json);

foreach (var feature in deserialize.features)
{
    if (feature.properties.Code == 2)
    {
        feature.properties.Landuse = "ppp"; // 替换为你的目标值
    }
}

string output = Newtonsoft.Json.JsonConvert.SerializeObject(deserialize);
File.WriteAllText(myPath, output);

额外注意事项 #

• 确保C#属性名与GeoJSON中的键完全一致（包括大小写，比如GeoJSON中的latitude是小写，C#属性也要对应）
• 如果需要更灵活的大小写匹配，可以给C#属性添加[JsonProperty("键名")]特性，示例：

  [JsonProperty("latitude")]
  public double Latitude { get; set; }
  

内容的提问来源于stack exchange，提问作者mohammad