文章目錄
- 一、前言
- 二、對象遞歸引用Json序列化異常案例
-
- 1、領域層對象關系:
- 2、應用層對象關系:
- 3.1、關聯查詢方式:AbpVnext
- 3.2、關聯查詢方式:Abp
- 4、查詢結果Json序列化異常:
- 5、解決方案:
- 三、總結
一、前言
應用層涉及到從資料庫提取資料記錄,轉換成對應的DTO,然後架構自動Json序列化,傳回前端;
在Domain領域層建立的領域對象DO通常帶有關系綁定,1:1 或者1:N , 自然Application應用層的資料傳輸對象 DTO也會帶有與之對應關系的DTO;
當查詢A記錄 想要把A記錄關聯的B記錄也一并查詢并傳回的時候,記錄查詢雖然成功,但是在進行Json序列化的時候會提示要轉換的對象出現循環遞歸引用,且超過最大32層循環嵌套深度,直接報JsonException異常。
二、對象遞歸引用Json序列化異常案例
1、領域層對象關系:
//巡航類 Cruise.cs
public class Cruise : Entity<int>, IHasCreationTime, IHasModificationTime
{
/// <summary>
/// 區域巡檢點清單:1條路徑多個巡檢點
/// </summary>
public virtual List<Cruise_Points> Cruise_Points { get; set; }
}
//巡檢點:Cruise_Points.cs
public class Cruise_Points : Entity<int>, IHasModificationTime, IHasCreationTime
{
/// <summary>
/// 預置巡航ID
/// </summary>
public virtual int Cruise_Id { get; set; }
[ForeignKey("Cruise_Id")]
public virtual Cruise Cruise { get; set; }
}
//巡檢日志:Device_Warns.cs
public class Device_Warns : Entity<int>, IHasCreationTime, IHasModificationTime
{
/// <summary>
/// 巡檢路徑id:預置巡航/區域巡航
/// </summary>
public int? CruiseId { get; set; }
[ForeignKey("CruiseId")]
public Cruise Cruise { get; set; }
/// <summary>
/// 巡檢點位id:預置巡檢點位/區域巡檢點位
/// </summary>
public int? CruisePointId { get; set; }
[ForeignKey("CruisePointId")]
public Cruise_Points Cruise_Point { get; set; }
}
2、應用層對象關系:
//CruiseDto.cs:巡檢路徑
public class CruiseDto : EntityDto<int>
{
/// <summary>
/// 區域巡檢點清單 區域巡檢點清單:1條路徑多個巡檢點
/// </summary>
public List<CruisePointDto> Cruise_Points { get; set; }
}
//CruisePointDto.cs:巡檢點位
public class CruisePointDto : EntityDto<int>
{
/// <summary>
/// 巡航路徑ID
/// </summary>
public virtual int Cruise_Id { get; set; }
public CruiseDto Cruise { get; set; }
}
//WarnsDto.cs:告警記錄中包含 巡檢路徑 和巡檢點位
public class WarnsDto : EntityDto<int>
{
/// <summary>
/// 巡檢路徑id:預置巡航/區域巡航
/// </summary>
public int CruiseId { get; set; }
/// <summary>
/// 預置巡航記錄
/// </summary>
public virtual CruiseDto Cruise { get; set; }
/// <summary>
/// 巡檢點位id:預置巡檢點位/區域巡檢點位
/// </summary>
public int CruisePointId { get; set; }
/// <summary>
/// 區域巡航 巡檢點
/// </summary>
public CruisePointDto Cruise_Point { get; set; }
}
3.1、關聯查詢方式:AbpVnext
public class WarnsAppService : CrudAppService<Device_Warns, WarnsDto, int, WarnsPagedResultRequestDto, CreateWarnsDto, WarnsDto>, IWarnsAppService
{
public WarnsAppService(IRepository<Device_Warns, int> repository) : base(repository)
{
}
/// <summary>
/// 重新翻頁查詢
/// </summary>
protected override IQueryable<Device_Warns> CreateFilteredQuery(WarnsPagedResultRequestDto input)
{
return this.ReadOnlyRepository.WithDetails(p=>p.Device,p => p.Cruise,prop=>prop.Cruise_Point)
.WhereIf(input.Device_Id != null, p => p.Device_Id == input.Device_Id);
}
}
}
//注意代碼中的 this.ReadOnlyRepository.WithDetails
3.2、關聯查詢方式:Abp
//類似這種寫法
return await _context.Device_Warns.Include(p => p.Cruise,P.Cruise_Point).FirstOrDefaultAsync(p=>p.id=2);
4、查詢結果Json序列化異常:
提示遞歸應用嵌套,超過Json序列化最大嵌套深度;
System.Text.Json.JsonException: A possible object cycle was detected which is not supported. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32.
at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_SerializerCycleDetected(Int32 maxDepth)
at System.Text.Json.JsonSerializer.Write(Utf8JsonWriter writer, Int32 originalWriterDepth, Int32 flushThreshold, JsonSerializerOptions options, WriteStack& state)
at System.Text.Json.JsonSerializer.WriteAsyncCore(Stream utf8Json, Object value, Type inputType, JsonSerializerOptions options, CancellationToken cancellationToken)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
at Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter.WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|29_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters()
— End of stack trace from previous location where exception was thrown —
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
5、解決方案:
在應用層 GasMonitoringApplicationAutoMapperProfile.cs 檔案中添加實體類轉換配置
public class GasMonitoringApplicationAutoMapperProfile : Profile
{
public GasMonitoringApplicationAutoMapperProfile()
{
CreateMap<Cruise, CruiseDto>()
.ForMember(x=>x.Cruise_Points,opt=>opt.Ignore());
CreateMap<CruiseDto, Cruise>(MemberList.Source); //以Dto資料為準進行轉換
CreateMap<CreateCruiseDto, Cruise>(MemberList.Source); //隻檢測Dto中屬性 Validate
}
}
}
.ForMember(x=>x.Cruise_Points,opt=>opt.Ignore()); 可有效解決循環遞歸引用問題
但是也會存在問題 在Cruise查詢的時候 就無法關聯查詢出對應的 Cruise_Points 清單了:不過這種查詢需求一般不會有
三、總結
網上還有其他若幹方法,比如在某個關聯屬性上面添加 [JsonIgnore]屬性以忽略Json序列化;
又或者引入Microsoft.AspNetCore.Mvc.NewtonsoftJson 包,然後Startup中添加 Json序列化忽略遞歸引用;
參考文章:https://www.mmbyte.com/article/142486.html