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Why isn't Generic Casting working on this section of code?

IQueryable<T> IS3Repository.FindAllBuckets<T>()
{
  IQueryable<object> list = _repository.GetAllBuckets().Cast<object>().AsQueryable();
  return list == null ? default(T) : (T)list;
}

This is an error: Error 3 Cannot implicitly convert type 'T' to 'System.Linq.IQueryable'. Explicit conversion exists (are you missing the listing?)

I am implementing this interface:

 IQueryable<T> FindAllBuckets<T>();

What is the problem?

Here's what I've tried:

  • IQueryable<T> IS3Repository.FindAllBuckets<T>()
{
    IQueryable<object> list = _repository
                              .GetAllBuckets()
                              .Cast<object>().AsQueryable();

    return list == null ? list.DefaultIfEmpty().AsQueryable() : list; }
+2


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2 answers


You are casting list

in T

, but the return value FindAllBuckets

is of type IQueryable<T>

.

Depending on the return type, _repository.GetAllBuckets()

this should work:



IQueryable<T> IS3Repository.FindAllBuckets<T>()
{
    return _repository.GetAllBuckets()
                      .Cast<T>()
                      .AsQueryable();
}
+1


source


Try the following:

IQueryable<T> IS3Repository.FindAllBuckets<T>()
{
    IQueryable<T> list = _repository
                         .GetAllBuckets()
                         .Cast<T>()
                         .AsQueryable();

    return list ?? new List<T>().AsQueryable();
}


The main problem with your original approach is that you were trying to return an instance T

, not an instance IQueryable<T>

.

0


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