无法将“System.Collections.Generic.HashSet`1[System.String]”类型的对象转换为“System.String”类型

Question

我的代码很少，在创建数据迁移时出现此错误。

PS C:\Users\username\source\repos\ToDoAPI\ToDoAPI> dotnet ef migrations add initialmigration
Build started...
Build succeeded.
System.InvalidCastException: Unable to cast object of type 'System.Collections.Generic.HashSet`1[System.String]' to type 'System.String'.
   at Microsoft.EntityFrameworkCore.Migrations.Internal.SnapshotModelProcessor.<>c.<.ctor>b__3_1(FieldInfo p)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.HashSet`1.UnionWith(IEnumerable`1 other)
   at System.Collections.Generic.HashSet`1..ctor(IEnumerable`1 collection, IEqualityComparer`1 comparer)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.SnapshotModelProcessor..ctor(IOperationReporter operationReporter, IModelRuntimeInitializer modelRuntimeInitializer)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
   at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)

程序.cs

builder.Services.AddDbContext<AppDbContext>(opt =>
    opt.UseSqlite(builder.Configuration.GetConnectionString("SqliteConnection")));

var app = builder.Build();

待办事项.cs

public class ToDo
{
    [Key]
    public string Id { get; set; }

    public string? ToDoName { get; set; }
}

数据

public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) 
    { 

    }

    public DbSet<ToDo> ToDos => Set<ToDo>();
}

我不知道这个转换发生在哪里，从而产生构建错误。

Answer 1

我也有同样的错误。

将

Microsoft.Data.SqlClient

升级到版本

5.2.0

，并将

Microsoft.EntityFrameworkCore.SqlServer

从

9.0.0-preview.1.24081.2

降级到

8.0.2

。还将

dotnet-ef

工具从

8.0.2

更新为

7.0.3

。

希望对您有帮助。