对其他模型上的多个导航属性重复使用外键

Question

这是外汇基金核心回购上相应github问题的交叉过账

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在多态关系得到支持之前，我正试图采用现有的模式，并从中创建一些有用的导航属性。不幸的是，我在许多方面都遇到了困难，尽管我觉得最接近的方法是通过以下途径：

public class Entitlement
{
public Guid Id { get; set; }
public Guid EntitleableId { get; set; }
}
public class Tenant
{
public Guid Id { get; set; }
public ICollection<Entitlement> AssignedEntitlements { get; set; }
}
// note: Consider User and Firm the same as tenant in this example.

// ...
modelBuilder
.Entity<Tenant>()
.HasMany((tenant) => tenant.AssignedEntitlements)
.WithOne()
.IsRequired(true)
.HasForeignKey((entitlement) => entitlement.EntitleableId)
.HasPrincipalKey((tenant) => tenant.Id);
modelBuilder
.Entity<Firm>()
.HasMany((firm) => firm.AssignedEntitlements)
.WithOne()
.IsRequired(true)
.HasForeignKey((entitlement) => entitlement.EntitleableId)
.HasPrincipalKey((firm) => firm.Id);
modelBuilder
.Entity<User>()
.HasMany((user) => user.AssignedEntitlements)
.WithOne()
.IsRequired(true)
.HasForeignKey((entitlement) => entitlement.EntitleableId)
.HasPrincipalKey((user) => user.Id);
// ...

使用时，我似乎无法检索到任何内容

dbContext.Tenants.Include((t) => t.AssignedEntitlements);

实体框架生成有效查询(.ToQueryString()(：

SELECT t.id, t.created_at, t."default", t.deleted_at, t.label, t.name, t.updated_at, e.id, e.created_at, e.entitleable_id, e.entitleable_type, e.feature, e.source_id, e.source_type, e.updated_at
FROM tenants AS t
LEFT JOIN entitlements AS e ON t.id = e.entitleable_id
ORDER BY t.id, e.id

运行生成的SQL返回正确的数据，但任何在查询对象上运行.First(), FirstOrDefault(), etc...的尝试似乎都会导致问题：

System.InvalidOperationException: Sequence contains no matching element
at System.Linq.ThrowHelper.ThrowNoMatchException()
at System.Linq.Enumerable.First[TSource](IEnumerable`1 source, Func`2 predicate)
at MyProject.Conventions.Feature..ctor(String name)
at lambda_method374(Closure , QueryContext , DbDataReader , ResultContext , SingleQueryResultCoordinator )
at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.<PopulateIncludeCollection>g__ProcessCurrentElementRow|60_0[TIncludingEntity,TIncludedEntity](<>c__DisplayClass60_0`2& )
at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.PopulateIncludeCollection[TIncludingEntity,TIncludedEntity](Int32 collectionId, QueryContext queryContext, DbDataReader dbDataReader, SingleQueryResultCoordinator resultCoordinator, Func`3 parentIdentifier, Func`3 outerIdentifier, Func`3 selfIdentifier, IReadOnlyList`1 parentIdentifierValueComparers, IReadOnlyList`1 outerIdentifierValueComparers, IReadOnlyList`1 selfIdentifierValueComparers, Func`5 innerShaper, INavigationBase inverseNavigation, Action`2 fixup, Boolean trackingQuery)
at lambda_method376(Closure , QueryContext , DbDataReader , ResultContext , SingleQueryResultCoordinator )
at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
at lambda_method377(Closure , QueryContext )
at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)
at MyProject.Global.Api.Controller.TestController.Test(MyProjectGlobalContext context) in /home/me/Development/MyProject/global/MyProject.Global.Api/src/Controller/TestController.cs:line 19
at lambda_method289(Closure , Object )
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Logged|12_1(ControllerActionInvoker invoker)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.Policy.AuthorizationMiddlewareResultHandler.HandleAsync(RequestDelegate next, HttpContext context, AuthorizationPolicy policy, PolicyAuthorizationResult authorizeResult)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Answer 1

看起来您的代码导致了此异常。MyProject.Conventions.Feature构造函数包含为某个空记录集调用First扩展的代码。