IncludeEFU - Sequence contains no matching element

[vindberg]

Hi, im getting the "Sequence contains no matching element" when there is no entries in the included collection. Have tried to add DefaultIfEmpty with no luck. How should the query look like? Im selecting into a new class.

[InvalidOperationException: Sequence contains no matching element] System.Linq.Enumerable.First(IEnumerable1 source, Func2 predicate) +482 EntityFramework.Utilities.EFQueryHelpers.GetFKProperty(ReadOnlyCollection1 cSpaceTables) +334 EntityFramework.Utilities.EFQueryHelpers.GetForeignKeyGetter(ReadOnlyCollection1 cSpaceTables) +59 EntityFramework.Utilities.EFQueryHelpers.IncludeEFU(IQueryable1 query, DbContext context, Expression1 collectionSelector) +368

Thanks in advance!

[titobf]

Same problem here:

System.InvalidOperationException: Sequence contains no matching element at System.Linq.Enumerable.First[TSource](IEnumerable1 source, Func2 predicate) at EntityFramework.Utilities.EFQueryHelpers.GetFKProperty[T,TChild](ReadOnlyCollection1 cSpaceTables) at EntityFramework.Utilities.EFQueryHelpers.GetForeignKeyGetter[T,TChild](ReadOnlyCollection1 cSpaceTables) at EntityFramework.Utilities.EFQueryHelpers.IncludeEFU[T,TChild](IQueryable1 query, DbContext context, Expression1 collectionSelector)

[MikaelEliasson]

Are you using projections? I didn't figure out how to get that to work yet.

[titobf]

Hi Mikael. And thanks so much for your time.

This is my query:

IQueryable query = _unitOfWork.Courses.Query() .IncludeEFU(_unitOfWork.Context, c => c.PatientInteractions.Where(pi => pi.PatientId == userId)) .IncludeEFU(_unitOfWork.Context, c => c.Ratings.Where(r => r.AppUserId == userId)) .Where(c => !c.IsDeleted)

[MikaelEliasson]

Could you share classes? I'm interested in seeing the the foreign keys and navigation properties

[zaideygrek]

Hi Mickael. I have the same problem. Have you found a solution ? Thanks

[zaideygrek]

Ok I found, there was a problem navigation. Thanks a lot for utilities !

[MikaelEliasson]

@zaideygrek Could you share what the problem was? I will try to improve this part of the library.

[titobf]

Mikael, sorry I miss the notification of your message (I have to unwatch so many repositories).

I have added the source code to my project and I found the line where the exception is thrown:

EFQueryHelpers.cs line 173:

var fk = cSpaceChildType.NavigationProperties.First(n => n.ToEndMember.GetEntityType().Name == typeof(T).Name).GetDependentProperties().First();

The problem is that I'm querying over the Course class and including a navigation property that is defined in a parent class so this comparison doesn't succeed: n.ToEndMember.GetEntityType().Name == typeof(T).Name

n.ToEndMember.GetEntityType().Name returns "Product" typeof(T).Name returns "Course"

public abstract class Product : TrackableEntity
{
    public ICollection<Rating> Ratings { get; set; }
}

public class Course : Product
{
}

public class Rating : DomainEntity
{
    public int ProductId { get; set; }
    public Product Product { get; set; }
}

I'll try to find a solution for this.

[titobf]

Can't find a way to get the real type out from the EntityType and I'm not sure it will be possible. Here is an unanswered question about that: http://stackoverflow.com/questions/16700457/how-do-i-get-the-corresponding-poco-object-type-from-an-entity-framework-metadat

I was thinking about using typeof(Base).IsAssignableFrom(typeof(Derived)): http://stackoverflow.com/questions/2742276/in-c-how-do-i-check-if-a-type-is-a-subtype-or-the-type-of-an-object

[MikaelEliasson]

Thank you for the repro. I'll take a look

[titobf]

Mikael, I found another issue that is possibly related to this one.

The line 72 in EFQueryHelpers:

var baseType = typeof(T).BaseType != typeof(object) ? typeof(T).BaseType : typeof(T);

is throwing:

Mapping and metadata information could not be found for EntityType 'XXXXX.Entities.BaseClasses.TrackableEntity'.

if I replace that line with:

                var baseType = typeof(T);

it works (ugly hack);

TrackableEntity is an entity that almost all my entities derive from. It has common properties about change tracking (CreatedOn, ModifiedOn, etc).

I find so useful the filtering provided by IncludeEFU. EF should include a functionality like that. I don't want to use projections to do the filtering (http://stackoverflow.com/a/3544878/1454888) because I lose the auto-mapping of the properties.