扩展属性中的 Odata 过滤不起作用

Question

我们创建了一个 .NET Core API，它使用 Odata 来过滤、select 和扩展数据。数据存储在 Microsoft SQL 服务器数据库中，并通过 EntityFramework 核心（代码优先）检索。我们使用 Linq 投影，因此 Odata 过滤器直接应用于查询，但这会在以下情况下出错：

检索结果列表时，例如作者扩展了书籍，一切正常。在展开的书籍中进行过滤时会出错，例如：https://localhost:44316/odata/authors?$expand=Books($filter=Id eq 1)

    System.InvalidOperationException: The LINQ expression 'DbSet<Book>()
    .Where(b0 => EF.Property<Nullable<int>>(EntityShaperExpression: 
        EntityType: Author
        ValueBufferExpression: 
            ProjectionBindingExpression: EmptyProjectionMember
        IsNullable: False
    , "Id") != null && object.Equals(
        objA: (object)EF.Property<Nullable<int>>(EntityShaperExpression: 
            EntityType: Author
            ValueBufferExpression: 
                ProjectionBindingExpression: EmptyProjectionMember
            IsNullable: False
        , "Id"), 
        objB: (object)EF.Property<Nullable<int>>(b0, "AuthorId")))
    .Where(b0 => b0
        .ToDto().Id == __TypedProperty_1)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.<VisitMethodCall>g__CheckTranslated|15_0(ShapedQueryExpression translated, <>c__DisplayClass15_0& )
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.TranslateSubquery(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberAssignment(MemberAssignment memberAssignment)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberInit(MemberInitExpression memberInitExpression)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberAssignment(MemberAssignment memberAssignment)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberInit(MemberInitExpression memberInitExpression)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Translate(SelectExpression selectExpression, Expression expression)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateSelect(ShapedQueryExpression source, LambdaExpression selector)
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_0`1.<ExecuteAsync>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 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.EntityQueryable`1.GetAsyncEnumerator(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadInternal[T](Object value)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor.ExecuteAsyncEnumerable(ActionContext context, ObjectResult result, Object asyncEnumerable, Func`2 reader)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>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 ---
   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__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>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)

我已经在 odata github 页面上创建了一个 issue，但它只部分解决了我们的问题，我们对第二条评论没有任何反应。

这是我们用来从数据库模型映射到 DTO 的代码。

public static IQueryable<AuthorDTO> ProjectTo(IQueryable<Author> source)
{
    return source?.Select(ProjectToAuthorDto());
}

private static Expression<Func<Author, AuthorDTO>> ProjectToAuthorDto()
{
    return author => new AuthorDTO
    {
        Firstname = author.Firstname,
        Lastname = author.Lastname,
        Id = author.Id,
        Books = author.Books.Select(book => book.ToDto())
    };
}

public static BookDTO ToDto(this Book book)
{
    return ProjectToBookDto().Compile().Invoke(book);
}

private static Expression<Func<Book, BookDTO>> ProjectToBookDto()
{
    return book => new BookDTO
    {
        AuthorId = book.AuthorId,
        Author = book.Author.ToDto(),
        Id = book.Id,
        ISBN = book.ISBN,
        Title = book.Title
    };
}

当我执行内联映射时，一切正常（见下图），但这不是解决方案，因为映射需要可重用。

此问题仅在 Odata 与 Linq 投影结合使用时出现。当我们删除 Odata 包时，一切都会按预期返回。此外，当我们在返回结果之前执行查询时（通过添加 .ToList()），我们确实得到了预期的结果，但是，odata 过滤器并未应用于查询。我们在 .NET Core 3.1 和 .NET 5 中都有这个问题。我在 this repo.

中为我们的问题创建了一个极其简化的最小版本

我们运行没有想法，不知道接下来要尝试什么。我希望任何人都知道如何让过滤器正常工作。

提前致谢！

编辑

我按照 Svyatoslav Danyliv 的建议修改了助手。

public static IQueryable<AuthorDTO> ProjectTo(IQueryable<Author> source)
{
    return source?.Select(item => item.ToDto());
}

[Computed]
public static AuthorDTO ToDto(this Author author)
{
    return new AuthorDTO
    {
        Firstname = author.Firstname,
        Lastname = author.Lastname,
        Id = author.Id,
        Books = author.Books.Select(book => book.ToDto())
    };
}
[Computed]
public static BookDTO ToDto(this Book book)
{
    return new BookDTO
    {
        AuthorId = book.AuthorId,
        //Author = book.Author.ToDto(),
        Id = book.Id,
        ISBN = book.ISBN,
        Title = book.Title
    };
}

并通过以下方式调用它：

// Convert to DTO
IQueryable<AuthorDTO> result = CustomMapper.ProjectTo(authors);

return Ok(result.Decompile());

错误消失了，但现在结果被截断了：

我还在 SQL Server Profiler 中看到当我应用 $filter 时不再执行查询。

当我使用 .DecompileAsync() 时，出现以下错误：

System.InvalidOperationException: The LINQ expression '$it' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberAssignment(MemberAssignment memberAssignment)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberInit(MemberInitExpression memberInitExpression)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at System.Linq.Expressions.ExpressionVisitor.VisitLambda[T](Expression`1 node)
   at System.Linq.Expressions.Expression`1.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitConditional(ConditionalExpression conditionalExpression)
   at System.Linq.Expressions.ConditionalExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberAssignment(MemberAssignment memberAssignment)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberInit(MemberInitExpression memberInitExpression)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberAssignment(MemberAssignment memberAssignment)
   at System.Linq.Expressions.ExpressionVisitor.VisitMemberBinding(MemberBinding node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitMemberInit(MemberInitExpression memberInitExpression)
   at System.Linq.Expressions.MemberInitExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.Translate(SelectExpression selectExpression, Expression expression)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryableMethodTranslatingExpressionVisitor.TranslateSelect(ShapedQueryExpression source, LambdaExpression selector)
   at Microsoft.EntityFrameworkCore.Query.QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
   at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_0`1.<ExecuteAsync>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 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 DelegateDecompiler.EntityFrameworkCore.AsyncDecompiledQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetAsyncEnumerator(CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadInternal[T](Object value)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor.ExecuteAsyncEnumerable(ActionContext context, ObjectResult result, Object asyncEnumerable, Func`2 reader)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>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 ---
   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__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>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)

有什么想法吗？再次感谢！

编辑 2

Svyatoslav Danyliv 建议使用下面的代码并修复了上面的错误！

[EnableQuery(HandleNullPropagation = HandleNullPropagationOption.False]

感谢您的努力！

最终（工作）代码：

public static IQueryable<AuthorDTO> ProjectTo(IQueryable<Author> source)
{
    return source?.Select(item => item.ToDto());
}

[Computed]
public static AuthorDTO ToDto(this Author author)
{
    return new AuthorDTO
    {
        Firstname = author.Firstname,
        Lastname = author.Lastname,
        Id = author.Id,
        Books = author.Books.Select(book => book.ToDto())
    };
}      

[Computed]
public static BookDTO ToDto(this Book book)
{
    return new BookDTO
    {
        AuthorId = book.AuthorId,
        //Author = book.Author.ToDto(),
        Id = book.Id,
        ISBN = book.ISBN,
        Title = book.Title
    };
}

并调用它：

IQueryable<AuthorDTO> result = CustomMapper.ProjectTo(authors);

return Ok(result.DecompileAsync());

Answer 1

嗯，这是使用表达式树时的常见错误。您不能以这种方式使用 ToDto。 LINQ 翻译器必须看到表达式树而不是编译的 lambda。

我知道有两个库可以帮助您实现此结果：

https://github.com/hazzik/DelegateDecompiler

https://github.com/axelheer/nein-linq

然后你必须重写你的辅助方法（使用 DelegateDecompiler）：

[Computed]
public static BookDTO ToDto(this Book book)
{
    return new BookDTO
    {
        AuthorId = book.AuthorId,
        Author = book.Author.ToDto(),
        Id = book.Id,
        ISBN = book.ISBN,
        Title = book.Title
    };
}

[Computed]
public static AuthorDTO ToDto(this Author author)
{
   ...
}

并使用文档中指定的 .Decompile() 或 .DecompileAsync()

性能和查询翻译注意事项

EnableQuery 属性应初始化为：

[EnableQuery(HandleNullPropagation = HandleNullPropagationOption.False, 
   HandleReferenceNavigationPropertyExpandFilter = false)]

此外，在 OData 错误期间，查询将 select 扩展项目两次：使用过滤器和不使用文件管理器。这是当前 OData 库的限制。可能应该在他们的存储库中创建问题。

扩展属性中的 Odata 过滤不起作用

Odata filtering in expanded property does not work

c#

linq

odata

entity-framework-core

asp.net-core

扩展 属性 中的 Odata 过滤不起作用

Odata filtering in expanded property does not work

c#

linq

odata

entity-framework-core

asp.net-core

扩展属性中的 Odata 过滤不起作用