[英]How to deserialize complex JSON with Newtonsoft?
我是論壇的新手，我有一個問題。
我正在嘗試使用 Newtonsoft 反序列化 NASA API 的 Neo Feed，但出現此錯誤
Newtonsoft.Json.JsonSerializationException：無法將當前 JSON 對象（例如 {"name":"value"}）反序列化為類型“System.Collections.Generic.IEnumerable
1[NasaApi.Models.Near_Earth_Objects]' because the type requires a JSON array (eg [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (eg [1,2,3]) or change the deserialized type so that it is a normal .NET type (eg not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object. Path 'links', line 1, position 9. at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent) at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value) at NasaApi.Services.NearEarthObjectService.GetAllNeos() in C:\Users\santanitaxx1050\Desktop\NasaApi\NasaApi\Services\NearEarthObjectService.cs:line 18 at lambda_method5(Closure , Object ) at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask1[NasaApi.Models.Near_Earth_Objects]' because the type requires a JSON array (eg [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (eg [1,2,3]) or change the deserialized type so that it is a normal .NET type (eg not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object. Path 'links', line 1, position 9. at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent) at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value) at NasaApi.Services.NearEarthObjectService.GetAllNeos() in C:\Users\santanitaxx1050\Desktop\NasaApi\NasaApi\Services\NearEarthObjectService.cs:line 18 at lambda_method5(Closure , Object ) at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask1[NasaApi.Models.Near_Earth_Objects]' because the type requires a JSON array (eg [1,2,3]) to deserialize correctly. To fix this error either change the JSON to a JSON array (eg [1,2,3]) or change the deserialized type so that it is a normal .NET type (eg not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object. Path 'links', line 1, position 9. at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent) at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value) at NasaApi.Services.NearEarthObjectService.GetAllNeos() in C:\Users\santanitaxx1050\Desktop\NasaApi\NasaApi\Services\NearEarthObjectService.cs:line 18 at lambda_method5(Closure , Object ) at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments) at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask1 actionResultValueTask) 在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker 調用程序，任務 lastTask，下一個狀態，作用域范圍，對象狀態，布爾值已完成）在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow（ActionExecuted ContextSealed context) 在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) 在 Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker 調用程序, Task Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0（ResourceInvoker 調用程序，任務 lastTask，下一個狀態，作用域范圍，對象狀態，布爾 isCompleted）在 Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0（ResourceInvoker 調用程序，任務任務，IDisposable 范圍）在 Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0（ResourceInvoker 調用程序，任務任務, IDisposable 范圍) 在 Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger) 在 Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context) 在 Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext) 在 Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider) 在 Microsoft.AspNetCore.Diagnostics .DeveloperExceptionPageMiddleware.Invoke(HttpContext 上下文)標題
Accept: / Host: localhost:7008 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.79 Safari/537.36 :method: GET Accept-Encoding: gzip , 放氣, br 接受語言: es-ES,es;q=0.9 緩存控制: 無緩存郵遞員令牌: ec30b624-b8b6-770d-57ce-4b6dcda1ffc2 sec-gpc: 1 sec-fetch-site: none sec -fetch-mode：cors sec-fetch-dest：空
我試過了
public async Task<IEnumerable<Near_Earth_Objects>> GetAllNeos()
{
var json = await _httpClient.GetStringAsync($"feed?start_date=2021-11-07&end_date=2021-11-10&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2");
return JsonConvert.DeserializeObject<IEnumerable<Near_Earth_Objects>>(json);
}
有了這個JSON
{
"links": {
"next": "http://www.neowsapp.com/rest/v1/feed?start_date=2021-12-12&end_date=2021-12-15&detailed=false&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2",
"prev": "http://www.neowsapp.com/rest/v1/feed?start_date=2021-12-06&end_date=2021-12-09&detailed=false&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2",
"self": "http://www.neowsapp.com/rest/v1/feed?start_date=2021-12-09&end_date=2021-12-12&detailed=false&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2"
},
"element_count": 76,
"near_earth_objects": {
"2021-12-12": [
{
"links": {
"self": "http://www.neowsapp.com/rest/v1/neo/2004341?api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2"
},
"id": "2004341",
"neo_reference_id": "2004341",
"name": "4341 Poseidon (1987 KF)",
"nasa_jpl_url": "http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004341",
"absolute_magnitude_h": 16.05,
"estimated_diameter": {
"kilometers": {
"estimated_diameter_min": 1.6389095149,
"estimated_diameter_max": 3.6647130844
},
"meters": {
"estimated_diameter_min": 1638.9095149478,
"estimated_diameter_max": 3664.7130843945
},
"miles": {
"estimated_diameter_min": 1.0183708442,
"estimated_diameter_max": 2.277146434
},
"feet": {
"estimated_diameter_min": 5376.9998930214,
"estimated_diameter_max": 12023.337275805
}
},
"is_potentially_hazardous_asteroid": false,
"close_approach_data": [
{
"close_approach_date": "2021-12-12",
"close_approach_date_full": "2021-Dec-12 13:35",
"epoch_date_close_approach": 1639316100000,
"relative_velocity": {
"kilometers_per_second": "17.8282207618",
"kilometers_per_hour": "64181.5947426121",
"miles_per_hour": "39879.9470221525"
},
"miss_distance": {
"astronomical": "0.3316696597",
"lunar": "129.0194976233",
"kilometers": "49617074.634744839",
"miles": "30830620.5431592182"
},
"orbiting_body": "Earth"
}
],
"is_sentry_object": false
},
制作這個模型
public class Near_Earth_Objects
{
[JsonProperty("id")]
public int Id { get; set; }
[JsonProperty("name")]
public string Nombre { get; set; }
[JsonProperty("estimated_diameter:kilometers:estimated_diameter_min")]
public double DiametroMin { get; set; }
[JsonProperty("estimated_diameter:kilometers:estimated_diameter_max")]
public double DiametroMax { get; set; }
[JsonProperty("close_approach_data:relative_velocity:kilometers_per_hour")]
public double Velocidad { get; set; }
[JsonProperty("close_approach_data: close_approach_date")]
public DateTime Fecha { get; set; }
[JsonProperty("close_approach_date: orbiting_body")]
public string Planeta { get; set; }
}
我的反序列化代碼是這樣的
public async Task<IEnumerable<Near_Earth_Objects>> GetAllNeos()
{
var json = await _httpClient.GetStringAsync($"feed?start_date=2021-11-07&end_date=2021-11-10&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2");
return JsonConvert.DeserializeObject<IEnumerable<Near_Earth_Objects>>(json);
}
看看什么JSON響應在 POSTMAN 上試試這個：
謝謝大家！！ 對不起我的英語不好，我來自西班牙:)
這確實是一個復雜的模式，因此自動生成 DTO 並不容易。 因此，您不應為屬性使用自定義名稱。 這使得發現問題變得更加困難。
near_earth_objects部分實際上是日常觀察的字典。 與其創建一個near_earth_objects類，不如使用Dictionary<string,Observation[]> 。links包含指向提要中當前、下一頁和上一頁的鏈接。 這意味着您實際上可以創建一個類並在根級別和日常觀察中重用它您可以使用 DTO 生成器工具開始，但結果需要修改。 工具將無法識別near_earth_objects是字典，並且很容易最終為每個條目創建新類型。
DTO
使用您的 JSON 示例，我使用 Visual Studio 的Paste as Json創建了初始類，然后對其進行了修改以使其正常工作。
public class Rootobject
{
public PageLinks links { get; set; }
public int element_count { get; set; }
public Dictionary<string,Observation[]> near_earth_objects { get; set; }
}
public class PageLinks
{
public string? next { get; set; }
public string? prev { get; set; }
public string self { get; set; }
}
Observation類對links屬性使用相同的PageLinks類：
public class Observation
{
public PageLinks links { get; set; }
public string id { get; set; }
public string neo_reference_id { get; set; }
public string name { get; set; }
public string nasa_jpl_url { get; set; }
public float absolute_magnitude_h { get; set; }
public Estimated_Diameter estimated_diameter { get; set; }
public bool is_potentially_hazardous_asteroid { get; set; }
public Close_Approach_Data[] close_approach_data { get; set; }
public bool is_sentry_object { get; set; }
}
其余類不需要修改：
public class Estimated_Diameter
{
public Kilometers kilometers { get; set; }
public Meters meters { get; set; }
public Miles miles { get; set; }
public Feet feet { get; set; }
}
public class Kilometers
{
public float estimated_diameter_min { get; set; }
public float estimated_diameter_max { get; set; }
}
public class Meters
{
public float estimated_diameter_min { get; set; }
public float estimated_diameter_max { get; set; }
}
public class Miles
{
public float estimated_diameter_min { get; set; }
public float estimated_diameter_max { get; set; }
}
public class Feet
{
public float estimated_diameter_min { get; set; }
public float estimated_diameter_max { get; set; }
}
public class Close_Approach_Data
{
public string close_approach_date { get; set; }
public string close_approach_date_full { get; set; }
public long epoch_date_close_approach { get; set; }
public Relative_Velocity relative_velocity { get; set; }
public Miss_Distance miss_distance { get; set; }
public string orbiting_body { get; set; }
}
public class Relative_Velocity
{
public string kilometers_per_second { get; set; }
public string kilometers_per_hour { get; set; }
public string miles_per_hour { get; set; }
}
public class Miss_Distance
{
public string astronomical { get; set; }
public string lunar { get; set; }
public string kilometers { get; set; }
public string miles { get; set; }
}
測試模型
使用此模型，以下測試通過：
[Fact]
public async Task GetFeed()
{
var client = new HttpClient();
var url = "http://www.neowsapp.com/rest/v1/feed?start_date=2021-12-09&end_date=2021-12-12&detailed=false&api_key=Na1sKwJGK1HVeOF4Yx8aLNp4u8ygT5GSSMF26HQ2";
var feed = await client.GetFromJsonAsync<Rootobject>(url);
Assert.Equal(76,feed.element_count);
var allObservations = feed.near_earth_objects
.SelectMany(p => p.Value)
.ToList();
Assert.Equal(76,allObservations.Count);
}
錯誤是由於以下行：
JsonConvert.DeserializeObject<IEnumerable<Near_Earth_Objects>>(json);
您收到此錯誤是因為 API 返回單個對象但您想將其反序列化為 IEnumerable。
為了解決將其更改為：
JsonConvert.DeserializeObject<ApiResultDataModel>(json);
和ApiResultDataModel如下所示：
public class ApiResultDataModel
{
public Links links { get; set; }
public int element_count { get; set; }
public Dictionary<string, Near_Earth_Objects[]> near_earth_objects { get; set; }
}
public class Links
{
public string next { get; set; }
public string prev { get; set; }
public string self { get; set; }
}
通過這樣做，您的數據將被成功反序列化：
我希望這個答案對你有所幫助。 祝你好運。
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