C#解析JSON问题
问题描述:
我有以下JSON和我使用Json.NET(Newtonsoft.Json):C#解析JSON问题
{
"total_items": "62",
"page_number": "6",
"page_size": "10",
"page_count": "7",
"cars": {
"car": [
{
"car_name": "Honda",
"engines": {
"engine": [ <-- HONDA has multiple engines, so this is an array
{
"name": "1.2L"
},
{
"name": "1.8L"
}
]
},
"country": "Japan"
"image": {
"thumb": {
"url": "http://image_path/Honda.jpg" <-- Image provided
}
}
},
{
"car_name": "Ford",
"engines": {
"engine": { <-- FORD has single engine, so this is an object
"name": "2.2L"
}
},
"country": "Japan"
"image": null <-- image is null
},
{
"car_name": "VW",
"engines": null, <-- VW has no engines, so this is null
"country": "Germany"
"image": null <-- image is null
}
]
}
}
而且我有以下Car对象:
class Car
{
public Car() { }
public string Name { get; set; }
public string Country { get; set; }
public List<String> EngineNames { get; set; }
}
我需要处理所有以上3种情况(HONDA阵列,FORD对象阵列,VW空白阵列)。如果它不为空,则获取所有引擎名称。因此,例如上面,我EngineNames列表中3辆汽车将是:
Honda.EngineNames = {"1.2L", "1.8L"} // array in JSON
Ford.EngineNames = {"2.2L"} //object in JSON
VW.EngineNames = null //null in JSON
我需要解析上面的JSON得到车资料。我解析car_name和国家,但我不知道如何通过处理上述3种情况来解析所有引擎名称。
private Cars GetCars(string json)
{
dynamic data = (JObject)JsonConvert.DeserializeObject(json);
foreach (dynamic d in data.cars.car)
{
Car c = new Car();
c.Name = (string)d.SelectToken("car_name");
c.Country = (string)d.SelectToken("country");
// PROBLEM: This works fine for array or null in JSON above (HONDA and VW), but it errors on JSON object (in case of FORD)
// When handling FORD, I get error "'Newtonsoft.Json.Linq.JProperty' does not contain a definition for 'name'"
c.EngineNames = (d.engines != null ? ((IEnumerable)d.engines.engine).Cast<dynamic>().Select(e => (string)e.name) : null);
CarList.Add(c);
}
return CarList;
}
答
使用从here转换器(最初提出的重复,但这个问题曾与JSON其他一些问题)
你的类结构有待修改了一下。
望着这JSON:
"cars": { <-- cars is an object, not an array
"car": [ <-- the cars object actually contains the array
{
"car_name": "Honda",
"engines": { <-- same goes for this
"engine": [
{
因此,你需要写包装类,以正确反映了JSON。下面是我想出什么用:
public class Root
{
public CarHolder Cars {get;set;}
}
public class CarHolder
{
public IList<Car> Car { get; set; }
}
public class Car
{
public Car() { }
public string car_name { get; set; }
public string Country { get; set; }
public EngineHolder Engines { get; set; }
}
public class EngineHolder
{
[JsonConverter(typeof(SingleOrArrayConverter<Engine>))]
public List<Engine> Engine { get; set; }
}
public class Engine
{
public string Name { get; set; }
}
而且使用转换从上面的问题:
public class SingleOrArrayConverter<T> : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return (objectType == typeof(List<T>));
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
JToken token = JToken.Load(reader);
if (token.Type == JTokenType.Array)
{
return token.ToObject<List<T>>();
}
return new List<T> { token.ToObject<T>() };
}
public override bool CanWrite
{
get { return false; }
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
用法:
var result = JsonConvert.DeserializeObject<Root>(jsonStr);
Console.WriteLine(result.Cars.Car[0].Engines.Engine[0].Name == "1.2L");
Console.WriteLine(result.Cars.Car[0].Engines.Engine[1].Name == "1.8L");
Console.WriteLine(result.Cars.Car[1].Engines.Engine[0].Name == "2.2L");
Console.WriteLine(result.Cars.Car[2].Engines == null);
所有打印true
通过循环汽车&发动机
foreach(var car in result.Cars.Car)
{
if (car.Engines != null)
{
foreach(var engine in car.Engines.Engine)
{
var engineName = engine.Name;
}
}
}
答
你应该可以使用它作为你的类结构;
public class Rootobject
{
public string total_items { get; set; }
public string page_number { get; set; }
public string page_size { get; set; }
public string page_count { get; set; }
public Cars cars { get; set; }
}
public class Cars
{
public Car[] car { get; set; }
}
public class Car
{
public string car_name { get; set; }
public Engines engines { get; set; }
public string country { get; set; }
}
public class Engines
{
public object engine { get; set; }
}
//I created below class manually
public class Engine
{
public string name { get; set; }
}
我用VS的内置功能来生成这个。脚步;
- 打开一个新的cs文件。
- 复制您的JSON
- 转到编辑菜单>粘贴特殊
- 选择粘贴JSON作为类
一旦做到这一点,它应该只是一个创建了两个方法,序列化的问题,并反序列化。
与还原序列化/ deserialise方法
private static T Deserialise<T>(string json)
{
var myopject = JsonConvert.DeserializeObject<T>(json);
return myopject;
}
private static string Serialise<T>(T value)
{
var mycontent = JsonConvert.SerializeObject(value);
return mycontent;
}
我们测试上面的方法更新,你可以做到这一点。
var jsonstring = @"{
""total_items"": ""62"",
""page_number"": ""6"",
""page_size"": ""10"",
""page_count"": ""7"",
""cars"": {
""car"": [
{
""car_name"": ""Honda"",
""engines"": {
""engine"": [
{
""name"": ""1.2L""
},
{
""name"": ""1.8L""
}
]
},
""country"": ""Japan""
},
{
""car_name"": ""Ford"",
""engines"": {
""engine"": {
""name"": ""2.2L""
}
},
""country"": ""Japan""
},
{
""car_name"": ""VW"",
""engines"": null,
""country"": ""Germany""
}
]
}
}";
var myobject = Deserialise<Rootobject>(jsonstring);
//if you want to parse engines you can do something like this.
if (myobject.cars != null && myobject.cars.car != null && myobject.cars.car.Any())
{
foreach (Car car in myobject.cars.car)
{
if (car.engines != null && car.engines.engine != null)
{
bool isList = false;
try
{
var eng = Deserialise<Engine>(car.engines.engine.ToString());
}
catch
{
isList = true;
}
if (isList)
{
try
{
var eng = Deserialise<List<Engine>>(car.engines.engine.ToString());
}
catch
{
Debug.WriteLine("Not a list");
}
}
}
}
}
var myjson = Serialise(myobject);
为什么不将单个项目引擎放入一个项目的数组中?像:''引擎“:[{”name“:”2.2L“}]' – Steve
@Steve JSON提供给我,我没有做到。这是怎么回事,我需要解析它。谢谢 – pixel
可能的重复[如何使用JSON.net处理同一个属性的单个项目和数组](http://*.com/questions/18994685/how-to-handle-both-a-single- item-and-an-array-for-the-same-property-using-json-n) – Rob