从.NET Framework 4.52迁移到.NET Core后的通用存储库问题

本文关键字：NET 问题 存储 Core Framework 迁移 | 更新日期: 2023-09-27 18:14:29

我正在将遗留代码从.NET Framework 4.52迁移到netstandard1.4(FWIW，我也在从EF 6迁移到EF Core(。

我的问题源于IDbSet<T>目前没有在EF Core中实现。

在EF 6中，IDbSet<Plugin>.Add(entity)返回Plugin类型的代理。

在EF Core中，context.Set<Plugin>.Add(entity)返回{Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry`1[Dna.NetCore.Core.BLL.Entities.Plugins.Plugin]}。

在EF Core中从Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry`1[Dna.NetCore.Core.BLL.Entities.Plugins.Plugin]转换为Dna.NetCore.Core.BLL.Enties.Plugins.Plugin时，我得到以下异常。

Q-我该如何铸造？

EF 6 RepositoryBase.cs

public abstract class RepositoryBase<T, U>
    where T : class
    where U : DbContext, new()
{
    private U _dataContext;
    private readonly IDbSet<T> _dbset;
    public virtual T Add(T entity)
    {
        object dao =  _dbset.Add(entity);
        return dao as T;
    }

}

EF核心存储库Base.cs

public abstract class RepositoryBase<T>
    where T : class
{
    //private readonly IDbSet<T> _dbset;  // IDbSet is not implemented in .NET Core 1.0.1
    private readonly Microsoft.EntityFrameworkCore.DbSet<T> _dbset;
    private readonly CoreEFContext _context;
    protected RepositoryBase(CoreEFContext context)
    {
        _context = context;
        _dbset = _context.Set<T>();
    }
    public virtual T Add(T entity, out CustomMessage customMessage)
    {
        object dao = _dbset.Add(entity);
        return dao as T;
    }
}

GitHub中提供了该存储库。

在RepositoryBase.cs的第64行：

本地设置窗口：

这个_dbset。结果视图="枚举没有结果">
这个_上下文ChangeTracker.非公共成员。Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure.Istance.Entries[0]=确实包含实体

即时窗口：

(Dna.NetCore.Core.BLL.Entities.Plugins.Plugin(dao

"(Dna.NetCore.Core.BLL.Entities.Plugins.Plugin(dao"引发了类型为"System.InvalidCastException"的异常
数据：｛System.Collections.ListDictionaryInternal｝
HResult:-2147467262
帮助链接：null
InnerException：null
消息："指定的强制转换无效。">
来源：空
StackTrace:空

dao as T

"dao as T"引发了类型为"System.NullReferenceException"的异常
数据：｛System.Collections.ListDictionaryInternal｝
HResult:-2147467261
帮助链接：null
InnerException：null
消息："对象引用未设置为对象的实例。">
来源：空
StackTrace:空

dao.GetType((

｛Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry 1[Dna.NetCore.Core.BLL.Entities.Plugins.Plugin]}
Assembly: {Microsoft.EntityFrameworkCore, Version=1.0.1.0, Culture=neutral, PublicKeyToken=adb9793829ddae60}
AssemblyQualifiedName: "Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry 1[[Dna.NetCore.Core.LL.Enties.Plugins.Plugin，Dna-NetCore.Core.BLL，Version=1.0.0.0，Culture=neutral，PublicKeyToken=null]]，Microsoft.EntityFrameworks Core，Version=1.1.0.1.0，Culture=neutral、PublicKeyToken=adb9793829ddae60">
属性：Public | BeforeFieldInit
BaseType:｛Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry｝
ContainsGenericParameters:false
自定义属性：计数=0
声明的构造函数：｛System.Reflection.ConstructorInfo1｝
声明的事件：｛System.Reflection.EventInfo[0]｝
声明字段：｛System.Reflection.FieldInfo[0]｝
声明的成员：｛System.Reflection.MemberInfo[5]｝
声明的方法：｛System.Reflection.MethodInfo[3]｝
声明的嵌套类型：｛System.Reflection.TypeInfo.d_23｝
声明的属性：｛System.Reflection.PropertyInfo1｝
DeclaringMethod:"((System.RuntimeType((dao.GetType((((.DDeclaringMethod"引发了类型为"System.InvalidOperationException"的异常
DeclaringType:null
全名："Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry 1[[Dna.NetCore.Core.BLL.Entities.Plugins.Plugin, Dna.NetCore.Core.BLL, Version=1.0.1.0, Culture=neutral, PublicKeyToken=null]]"
GUID: {bbf992a5-ba4d-3ab3-8a66-fa5a37a909ae}
GenericParameterAttributes: '((System.RuntimeType)(dao.GetType())).GenericParameterAttributes' threw an exception of type 'System.InvalidOperationException'
GenericParameterPosition: '((System.RuntimeType)(dao.GetType())).GenericParameterPosition' threw an exception of type 'System.InvalidOperationException'
GenericTypeArguments: {System.Type[1]}
GenericTypeParameters: {System.Type[0]}
HasElementType: false
ImplementedInterfaces: {System.Type[1]}
IsAbstract: false
IsAnsiClass: true
IsArray: false
IsAutoClass: false
IsAutoLayout: true
IsByRef: false
IsCOMObject: false
IsClass: true
IsConstructedGenericType: true
IsEnum: false
IsExplicitLayout: false
IsGenericParameter: false
IsGenericType: true
IsGenericTypeDefinition: false
IsImport: false
IsInterface: false
IsLayoutSequential: false
IsMarshalByRef: false
IsNested: false
IsNestedAssembly: false
IsNestedFamANDAssem: false
IsNestedFamORAssem: false
IsNestedFamily: false
IsNestedPrivate: false
IsNestedPublic: false
IsNotPublic: false
IsPointer: false
IsPrimitive: false
IsPublic: true
IsSealed: false
IsSecurityCritical: true
IsSecuritySafeCritical: false
IsSecurityTransparent: false
IsSerializable: false
IsSpecialName: false
IsUnicodeClass: false
IsValueType: false
IsVisible: true
MemberType: TypeInfo
MetadataToken: 33554824
Module (System.Reflection.MemberInfo): {Microsoft.EntityFrameworkCore.dll}
Module: {Microsoft.EntityFrameworkCore.dll}
Name: "EntityEntry 1">
命名空间："Microsoft.EntityFrameworkCore.ChangeTracking">
反射类型：null
StructLayoutAttribute:｛System.Runtime.InteropServices.StructLayoutAttribute｝
TypeHandle:｛System.RuntimeTypeHandle｝
TypeInitializer:null
UnderlyingSystemType:｛Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry`1[Dna.NetCore.Core.BLL.Entities.Plugins.Plugin]｝

Plugin_UpdateHandler.cs第56行返回：

Dna.NetCore.Core.DAL.EFCore.Repository.RepositoryBase.Add返回nullDna-NetCore.Core.BLL.Enties.Plugins.Plugin

从.NET Framework 4.52迁移到.NET Core后的通用存储库问题

您应该能够通过DbSet上的Entity属性访问实体。您可以直接返回参数或访问EntityEntry<T>对象，让ER Core完全控制要做的事情：

public virtual T Add(T entity, out CustomMessage customMessage)
{
    var entry = _dbset.Add<T>(entity);
    ...
    return entry.Entity;
}

请注意，目前EF Core没有EF 6的代理功能。

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