Exception is thrown when materializing query with IQueryable<T>.AsOf(DateTime)

[dart13]

I have the following issue:

this linq query

var result = _context.DistributionListEntries .AsOf(pager.TimeIndex) .Where(x => x.DistributionListId == distributionListId) .Include(x => x.PlaceholderValues) .Skip((pager.PageNumber - 1) * pager.PageSize).Take(pager.PageSize) .AsNoTracking();

when materialized

return await result.ToListAsync();

throws this exception

Message:
System.NotImplementedException : Unhandled method: AsOf
Stack Trace: QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) MethodCallExpression.Accept(ExpressionVisitor visitor) ExpressionVisitor.Visit(Expression node) QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) MethodCallExpression.Accept(ExpressionVisitor visitor) ExpressionVisitor.Visit(Expression node) QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) MethodCallExpression.Accept(ExpressionVisitor visitor) ExpressionVisitor.Visit(Expression node) QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) MethodCallExpression.Accept(ExpressionVisitor visitor) ExpressionVisitor.Visit(Expression node) QueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) RelationalQueryableMethodTranslatingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression) MethodCallExpression.Accept(ExpressionVisitor visitor) ExpressionVisitor.Visit(Expression node) QueryCompilationContext.CreateQueryExecutor[TResult](Expression query) Database.CompileQuery[TResult](Expression query, Boolean async) QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async) <>c__DisplayClass12_0'1.<ExecuteAsync>b__0() CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func'1 compiler) CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func'1 compiler) QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken) EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken) EntityQueryable'1.GetAsyncEnumerator(CancellationToken cancellationToken) ConfiguredCancelableAsyncEnumerable'1.GetAsyncEnumerator() EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable'1 source, CancellationToken cancellationToken) DLPOCRepository.GetTemporalEntriesForDistributionList(Int64 distributionListId, TemporalPagingFilter pager) line 142 DLPOCRepositoryTest.TestDLRepositoryPaging() line 51 --- End of stack trace from previous location where exception was thrown ---

Entities

DistributionListEntry

and

PlaceholderValue

are marked as temporal
builder.Entity<DistributionListEntry>(dle => dle.HasTemporalTable()); builder.Entity<EntryPlaceholderValue>(epv => epv.HasTemporalTable());

and DbContext is initialized

 `services.AddDbContext<DLPOCContext>(
            opt => opt
                .UseSqlServer(Configuration.GetConnectionString("DLPOC"))
                .EnableTemporalTableQueries());`

Did I miss some configuration options?

Is there are sample project which implements 'efcore-temporal-query'?

[Adam-Langley]

Hi @dart13,
I can see in your stack trace that your RelationalQueryableMethodTranslatingExpressionVisitor is the default built-in one - not the AsOf implementation (AsOfQueryableMethodTranslatingExpressionVisitor).
The default implementation has no idea how to translate the AsOf method call - hence your error.

That particular expression visitor is replaced by the EnableTemporalTableQueries extension method that you have used (correctly) above.

Take a look in the source - there is a test which will skip over the registration if you are not utilising the internal service provider.

efcore-temporal-query/src/EFCore.Temporal.Query/Extensions/SqlServerAsOfEntityTypeBuilderExtensions.cs

Lines 21 to 34 in a544882

	// If service provision is NOT being performed internally, we cannot replace services.
	var coreOptions = optionsBuilder.Options.GetExtension<CoreOptionsExtension>();
	if (coreOptions.InternalServiceProvider == null)
	{
	return optionsBuilder
	// replace the service responsible for generating SQL strings
	.ReplaceService<IQuerySqlGeneratorFactory, AsOfQuerySqlGeneratorFactory>()
	// replace the service responsible for traversing the Linq AST (a.k.a Query Methods)
	.ReplaceService<IQueryableMethodTranslatingExpressionVisitorFactory, AsOfQueryableMethodTranslatingExpressionVisitorFactory>()
	// replace the service responsible for providing instances of SqlExpressions
	.ReplaceService<ISqlExpressionFactory, AsOfSqlExpressionFactory>();
	}
	else
	return optionsBuilder;

Try this test yourself at runtime, and see if this is your problem.

If you are using external service provisioning, you will not be able to use this library as-is. You will need to write your own 'EnableTemporalTableQueries' method (which is possible) - but you just need to manually register all the Ef Core services.

[dart13]

Hi @Adam-Langley ,

thank you for your prompt reply.
Bad initialization of dbcontext in unit test was the cause of the error. Hopefully, this complete answer you provided will help others as well.

I am hoping that MS will provide better support for temporal tables in EF core soon, until then I'll use this great plug-in you have created.

best regards
Darko