Query: Prevent client evaluation if query modifiers precede condition

[breyed]

The warning RelationalEventId.QueryClientEvaluationWarning is issued if Include precedes a condition when queries are chained. Code like this will trigger the warning:

IQueryable<Customer> subQuery = ...
var query = subQuery.AsTracking().Include(...).Single(condition)

By contrast, code like this does not:

IQueryable<Customer> subQuery = ...
var query = subQuery.Where(condition).AsTracking().Include(...).Single()

[smitpatel]

Can you post the warning text also?

[breyed]

Warning as error exception for warning 'RelationalEventId.QueryClientEvaluationWarning': The LINQ expression '([c].AccountNumber == __accountNumber_2)' could not be translated and will be evaluated locally. To suppress this Exception use the DbContextOptionsBuilder.ConfigureWarnings API. ConfigureWarnings can be used when overriding the DbContext.OnConfiguring method or using AddDbContext on the application service provider.

[tuespetre]

I've ~~~written up~~~ copy-paste-modified some very basic tests that use `AsTracking().Include()` before `Single(predicate)`, could you give us an example of what your subquery looks like?

[breyed]

IQueryable<Customer> subQuery =
    from c in Db.Customers
    where c.BranchId == branchId
    orderby c.LastName, c.FirstName
    select c;

[smitpatel]

@breyed - Which version of EF are you using?
I tried reproducing this, I received warning in both cases. In one it says cannot translate the equality (which is inside Single()) and in second it says cannot translate Single(). The cause is Single call which needs client evaluation to throw exception.
Can you share your full queries and model classes for reproduction of the issue?

Scratch that. I got repro.

[smitpatel]

The subquery has an orderby clause. In Sql you cannot have orderby inside a subquery. Therefore it fails to translate outer query and shows client eval warning.
In the case when where is before as tracking, the Re-Linq query parser flattens out the whole model so there is nothing other than Single() outside the subquery. If Where comes after AsTracking it cannot translate it to server.

[smitpatel]

Verify this is fixed when #7613 is closed.

[smitpatel]

@maumar - Assigning this should be fixed with lifting of order by.

[maumar]

Fixed in f022d66