json null

{
"ResourceId": 0,
"JsonKey": "Account",
"GroupId": 21,
"Locale": "en-US",
"JsonValue": {
"Columns": {
"2": "2",
"Title": "343434"
},
"Labels": {},
"Others": {},
"Tips": {}
}
}

第一种：使用对象的字段属性设置JsonProperty来实现（不推荐，因为需要手动的修改每个字段的属性）

public class UserInfo
{
  [JsonProperty("id")]
  public int Id{ set; get; }
  [JsonProperty("userName")]
  public string UserName{ set; get; }
}

第二种：使用newtonsoft.json来设置格式化的方式（推荐使用）

var user = new { Name = "john", Age = 19 }; 
 var serializerSettings = new JsonSerializerSettings
      {
        // 设置为驼峰命名
        ContractResolver = new CamelCasePropertyNamesContractResolver()
      };
var userStr = JsonConvert.SerializeObject(user, Formatting.None, serializerSettings);

26down voteaccepted

This should work:

var settings = new JsonSerializerSettings() { ContractResolver= new NullToEmptyStringResolver() };
var str = JsonConvert.SerializeObject(yourObj, settings);

public class NullToEmptyStringResolver : Newtonsoft.Json.Serialization.DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
    {
        return type.GetProperties()
                .Select(p=>{
                    var jp = base.CreateProperty(p, memberSerialization);
                    jp.ValueProvider = new NullToEmptyStringValueProvider(p);
                    return jp;
                }).ToList();
    }
}

public class NullToEmptyStringValueProvider : IValueProvider
{
    PropertyInfo _MemberInfo;
    public NullToEmptyStringValueProvider(PropertyInfo memberInfo)
    {
        _MemberInfo = memberInfo;
    }

    public object GetValue(object target)
    {
        object result =  _MemberInfo.GetValue(target);
        if (_MemberInfo.PropertyType == typeof(string) && result == null) result = "";
        return result;

    }

    public void SetValue(object target, object value)
    {
        _MemberInfo.SetValue(target, value);
    }
}