我正试图让Entity Framework处理一些值，这些值可以是许多不同的类型，具体取决于数据库也处理的某些元数据。
我的示例有点过大，因为我只在Int和String之间更改了我的值，但这是为了简化示例以更好地了解我的需求。
我的OnModelCreating看起来像这样：
builder.Entity<Survey>().HasMany(c => c.SurveyGroups).WithOne(c => c.Survey);
builder.Entity<SurveyGroup>().HasOne(c => c.Survey).WithMany(c => c.SurveyGroups).HasForeignKey(c => c.SurveyId);
builder.Entity<SurveyGroup>().HasIndex(c => new { c.SurveyId, c.Order }).IsUnique();
builder.Entity<SurveyGroupField>().HasIndex(c => new { c.SurveyGroupId, c.Order }).IsUnique();
builder.Entity<SurveyGroupField>().HasOne(c => c.SurveyGroup).WithMany(c => c.SurveyGroupFields).HasForeignKey(c => c.SurveyGroupId);
builder.Entity<SurveyGroupFieldTextValue>().HasKey(c => new { c.Owner, c.SurveyGroupFieldTextId });
builder.Entity<SurveyGroupFieldTextValue>().HasIndex(c => new { c.Owner, c.SurveyGroupFieldTextId }).IsUnique();
builder.Entity<SurveyGroupFieldNumberValue>().HasKey(c => new { c.Owner, c.SurveyGroupFieldNumberId});
builder.Entity<SurveyGroupFieldNumberValue>().HasIndex(c => new { c.Owner, c.SurveyGroupFieldNumberId }).IsUnique();
builder.Entity<SurveyGroupFieldText>().HasMany(c => c.Values).WithOne(c => c.SurveyGroupFieldText).HasForeignKey(c => c.SurveyGroupFieldTextId);
builder.Entity<SurveyGroupFieldNumber>().HasMany(c => c.Values).WithOne(c => c.SurveyGroupFieldNumber).HasForeignKey(c => c.SurveyGroupFieldNumberId);
事实：
希望我没有忘记任何事情，因为我创造了一个更轻松的场景，直到解决了这个问题：）
这是我的模型课
public class Survey
{
public string Id { get; set; }
public string Name { get; set; }
public ICollection<SurveyGroup> SurveyGroups { get; set; }
public Survey(string name)
{
Id = Guid.NewGuid().ToString();
Name = name;
}
public Survey(string name, ICollection<SurveyGroup> surveyGroups) : this(name)
{
SurveyGroups = surveyGroups;
}
}
public class SurveyGroup
{
public string Id { get; set; }
public int Order { get; set; } = 0;
public string Name { get; set; }
public Survey Survey { get; set; }
public string SurveyId { get; set; }
public ICollection<SurveyGroupField> SurveyGroupFields { get; set; }
public SurveyGroup(int order, string name)
{
Id = Guid.NewGuid().ToString();
Order = order;
Name = name;
}
public SurveyGroup(int order, string name, ICollection<SurveyGroupField> surveyGroupFields) : this(order, name)
{
SurveyGroupFields = surveyGroupFields;
}
}
public abstract class SurveyGroupField
{
public string Id { get; set; }
public int Order { get; set; } = 0;
public string Name { get; set; }
public string Description { get; set; }
public SurveyGroup SurveyGroup { get; set; }
public string SurveyGroupId { get; set; }
public string Discriminator { get; set; }
public SurveyGroupField(int order, string name, string description)
{
Id = Guid.NewGuid().ToString();
Order = order;
Name = name;
Description = description;
}
}
public class SurveyGroupFieldNumber : SurveyGroupField
{
public SurveyGroupFieldNumber(int order, string name, string description) : base(order, name, description)
{
}
public SurveyGroupFieldNumber(int order, string name, string description, ICollection<SurveyGroupFieldNumberValue> values) : this(order, name, description)
{
Values = values;
}
public SurveyGroupFieldNumber(int order, string name, string description, Func<SurveyGroupFieldNumber, ICollection<SurveyGroupFieldNumberValue>> func) : this(order, name, description)
{
Values = func.Invoke(this);
}
public ICollection<SurveyGroupFieldNumberValue> Values { get; set; }
}
public class SurveyGroupFieldNumberValue
{
public string Owner { get; set; }
public int Value { get; set; }
public SurveyGroupFieldNumber SurveyGroupFieldNumber { get; set; }
public string SurveyGroupFieldNumberId { get; set; }
public SurveyGroupFieldNumberValue(string owner, int value)
{
Owner = owner;
Value = value;
}
public SurveyGroupFieldNumberValue(string owner, int value, SurveyGroupFieldNumber surveyGroupFieldNumber) : this(owner, value)
{
SurveyGroupFieldNumber = surveyGroupFieldNumber;
SurveyGroupFieldNumberId = surveyGroupFieldNumber?.Id;
}
}
public class SurveyGroupFieldText : SurveyGroupField
{
public SurveyGroupFieldText(int order, string name, string description) : base(order, name, description)
{
}
public SurveyGroupFieldText(int order, string name, string description, ICollection<SurveyGroupFieldTextValue> values) : this(order, name, description)
{
Values = values;
}
public SurveyGroupFieldText(int order, string name, string description, Func<SurveyGroupFieldText, ICollection<SurveyGroupFieldTextValue>> func) : this(order, name, description)
{
Values = func.Invoke(this);
}
public ICollection<SurveyGroupFieldTextValue> Values { get; set; }
}
public class SurveyGroupFieldTextValue
{
public string Owner { get; set; }
public string Value { get; set; }
public SurveyGroupFieldText SurveyGroupFieldText { get; set; }
public string SurveyGroupFieldTextId { get; set; }
public SurveyGroupFieldTextValue(string owner, string value)
{
Owner = owner;
Value = value;
}
public SurveyGroupFieldTextValue(string owner, string value, SurveyGroupFieldText surveyGroupFieldText) : this(owner, value)
{
SurveyGroupFieldText = surveyGroupFieldText;
SurveyGroupFieldTextId = surveyGroupFieldText?.Id;
}
}
我的问题是，当我尝试包括抽象表（SurveyGroupField）时，每个项目都可以是SurveyGroupFieldText或SurveyGroupFieldNumber。
我正在尝试通过一个查询.Include对它们进行搜索，但是似乎不起作用。
_context.Entry(survey)
.Collection(i => i.SurveyGroups)
.Query()
.Include(c => c.SurveyGroupFields);
await inc.ThenInclude(c => (c as SurveyGroupFieldNumber).Values).ThenInclude(c => (c as SurveyGroupFieldText).Values).LoadAsync();
然后我得到这个异常
System.InvalidOperationException：无效的包含。
在Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.PopulateIncludeTree（IncludeTreeNode includeTreeNode，Expression expression）中的在Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.ProcessInclude（NavigationExpansionExpression源，表达式表达式，布尔值thenInclude） 在Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.VisitMethodCall（MethodCallExpression methodCallExpression） 在System.Linq.Expressions.MethodCallExpression.Accept（ExpressionVisitor访问者） 在System.Linq.Expressions.ExpressionVisitor.Visit（Expression节点） 在Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.Expand（表达式查询） 在Microsoft.EntityFrameworkCore.Query.QueryTranslationPreprocessor.Process（表达式查询） 在Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor [TResult]（表达式查询） 在Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery [TResult]（表达式查询，布尔异步） 在Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore [TResult]（IDatabase数据库，表达式查询，IModel模型，布尔异步） 在Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler。<> c__DisplayClass12_0
1.<ExecuteAsync>b__0() at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func1编译器处） 在Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery [TResult]（Object cacheKey，Func1 compiler) at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable1.GetAsyncEnumerator（CancellationToken cancelleToken） Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.IncludableQueryable2.GetAsyncEnumerator(CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.LoadAsync[TSource](IQueryable1的来源，CancellationToken cancelToken） 在D：\ Codes \ Development \ IPN.Survey \ ApiService \ Controllers \ SurveysController.cs：line 46中的ApiService.Controllers.SurveysController.GetSurvey（String id） 在lambda_method（Closure，Object） 在Microsoft.Extensions.Internal.ObjectMethodExecutorAwaitable.Awaiter.GetResult（） 在Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute（IActionResultTypeMapper映射器，ObjectMethodExecutor执行器，对象控制器，Object []参数） 在Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited | 12_0（ControllerActionInvoker调用程序，ValueTask`1 actionResultValueTask） 在Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.g__Awaited | 10_0（ControllerActionInvoker调用程序，Task lastTask，Next状态，Scope作用域，对象状态，布尔值isCompleted） 在Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow（ActionExecutedContextSealed上下文） 在Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next（状态和下一个，范围和范围，对象和状态，布尔值和isCompleted）处 在Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync（） ---从之前引发异常的位置开始的堆栈结束跟踪--- 在Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited | 19_0（ResourceInvoker调用程序，Task lastTask，Next状态，Scope作用域，对象状态，布尔值isCompleted） 在Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited | 17_0（ResourceInvoker调用程序，任务任务，IDisposable范围） 在Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask | 6_0（端点端点，任务requestTask，ILogger记录器） 在Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke（HttpContext上下文） 在Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke（HttpContext上下文）
但是，如果我对2个查询执行此操作，它将起作用。
var inc = _context.Entry(survey)
.Collection(i => i.SurveyGroups)
.Query()
.Include(c => c.SurveyGroupFields);
await inc.ThenInclude(c => (c as SurveyGroupFieldNumber).Values).LoadAsync();
await inc.ThenInclude(c => (c as SurveyGroupFieldText).Values).LoadAsync();
在一个查询中有什么方法可以做到吗？为什么只有两个查询有效？