How to write Repository method for .ThenInclude in EF Core 2

Question

I\'m trying to write a repository method for Entity Framework Core 2.0 that can handle returning child collections of properties using .ThenInclude, but I\'m having trouble

Answer 1

I found this repository method online and it does exactly what I wanted. Yared's answer was good, but not all the way there.

/// 

/// Gets the first or default entity based on a predicate, orderby delegate and include delegate. This method default no-tracking query.
/// 
/// The selector for projection.
/// A function to test each element for a condition.
/// A function to order elements.
/// A function to include navigation properties
/// True to disable changing tracking; otherwise, false. Default to true.
/// An  that contains elements that satisfy the condition specified by .
/// This method default no-tracking query.
public TResult GetFirstOrDefault(Expression> selector,
                                          Expression> predicate = null,
                                          Func, IOrderedQueryable> orderBy = null,
                                          Func, IIncludableQueryable> include = null,
                                          bool disableTracking = true)
{
    IQueryable query = _dbSet;
    if (disableTracking)
    {
        query = query.AsNoTracking();
    }

    if (include != null)
    {
        query = include(query);
    }

    if (predicate != null)
    {
        query = query.Where(predicate);
    }

    if (orderBy != null)
    {
        return orderBy(query).Select(selector).FirstOrDefault();
    }
    else
    {
        return query.Select(selector).FirstOrDefault();
    }
}

Usage:

var affiliate = await affiliateRepository.GetFirstOrDefaultAsync(
    predicate: b => b.Id == id,
    include: source => source
        .Include(a => a.Branches)
        .ThenInclude(a => a.Emails)
        .Include(a => a.Branches)
        .ThenInclude(a => a.Phones));