Agfdhyk

I've a project with the package
EntityFramework 6.1.0

and I'm working with DB-First Model

Some model entities has been extended in this way:

public interface IVersionable{

int VersionId{get;set;}

}

public interface IEditable{

bool IsEditable{get;set;}

}

public interface IFullFeatures:IVersionable,IEditable{}

public partial EntityOne:IFullFeatures{

   //This is the extension partial class for the auto-generated model class EntityOne that already has interface properties

}

public partial EntityTwo:IFullFeatures{

   //This is the extension partial class for the auto-generated model class EntityTwo that already has interface properties

}

Autogenerated classes EntityOne and EntityTwo has all the properties required by IFullFeatures, and for EntityTwo auto-generated file we've this ICollection:

public virtual ICollection<EntityOne> EntityOne {get;set;}

Finally I've got the extension method:

public static class FeaturesExtensionMethod{

     public static IQueryable<T> FilterEditable<T>(this IQueryable<T> source) where T:class,IEditable{

         return source.Where(s=>s.IsEditable);

     }

     public static IQueryable<T> FilterVersion<T>(this IQueryable<T> source, int versionId) where T:class,IVersionable{

         return source.Where(s=>s.VersionId==versionId);

     }

     public static IQueryable<T> FullFilter<T>(this IQueryable<T> source, int versionId) where T:class,IVersionable{

         return source.FilterEditable().FilterVersion(versionId);

     }

}

Then, when at runtime I execute this:

var everyEntitiTwo=ctx.EntityTwo.FullFilter(4).ToList();

there's no problem, it works fine and it filters... but when at runtime I execute this instead:

var test= ctx.EntityTwo.Include("EntityOne").Select(et=>et.EntityOne.AsQueryAble().FullFilter(4)).ToList()

I get this error:

LINQ to Entities does not recognize the method 'FullFilter' method, and this method cannot be translated into a store expression.

So the question is: what is wrong on my Extension methods? Why I get this error on the second case and not even in first one?

Thanks.

UPDATE

Thanks to Jon Hanna I got inspired to this alternative way to reach the same result:

I made a "proxy class" to get the filter, because the Expression < Func < entityOne,bool> > it's strongly typed, and I needed something more generic:

public static FilterProxies{

    public static GetProxiedFilter<T>(int versionId, bool onlyEditable) where T: class, IFullFeatures{

       Expression<Func<T,bool>> filteredExp

       if(onlyEditable){

          filteredExp=(iff=>iff.VersioneId==versionId&&iff.IsEditable);

       }

       else{

          filteredExp=(iff=>iff.VersioneId==versionId); 

       }

       return filteredExp;

   }

}

Then, in usage:

var filter=FilterProxies.GetProxiedFilter<EntityOne>(4,true);

var test= ctx.EntityTwo.Include("EntityOne").Select(et=>et.EntityOne.AsQueryAble().Where(filter)).ToList()

Hoping to be helpful updating this post, thanks to Jon for inspiring me to apply this solution

ctx.EntityTwo.FullFilter(4).ToList();

This gets immediately turned into

ctx.EntityTwo.Where(s => s.IsEditable).Where(s => s.VersionId == 4).ToList();

Which of course is something Entity Framework can handle.

var test= ctx.EntityTwo.Include("EntityOne").Select(et=>et.EntityOne.AsQueryAble().FullFilter(4)).ToList()

Because the use of your queryable extensions are within the query and acting on a different type of queryable, the methods calls are part of the expression passed to Entity Framework, and it doesn't know what FullFilter() does, and chokes on that point.

EF is not able to translate the method FullFilter to SQL, as you are using LINQ to Entities. You might need to use Linq to Objects

ctx.EntityTwo.ToList() before your method so it first gets the list of your object and then execute your method using that list, by doing that you are doing LINQ To Objects