Use Include() method in repository

.net, c#, compiler-errors, entity-framework

Solution

Try:

Change

Expression<Func<T, Boolean>> criteria

To

Expression<Func<T, object>> criteria

Edit: To Include multiple entities, you need to add an "include" extension:

public static class IncludeExtension
{
    public static IQueryable<TEntity> Include<TEntity>(this IDbSet<TEntity> dbSet,
                                            params Expression<Func<TEntity, object>>[] includes)
                                            where TEntity : class
    {
        IQueryable<TEntity> query = null;
        foreach (var include in includes)
        {
            query = dbSet.Include(include);
        }

        return query == null ? dbSet : query;
    }
}

Then you can use it like this:

repository.Include(x => x.Pack, x => x.Pack.Roles, ...).Select(x => x.Pack.Id).ToList();

Just make sure "repository" return a "DbSet" Object.

Problem

I have the following with EF 5: ``` var a = context.Posts.Include(x => x.Pack).Select(x => x.Pack.Id).ToList(); ``` This works. Then I tried to replicate this in my generic repository: ``` public IQueryable<T> Include<T>(Expression<Func<T, Boolean>> criteria) where T : class { return _context.Set<T>().Include(criteria); } ``` But in this case I am not able to do the following: ``` var b = repository.Include<Post>(x => x.Pack).Select(x => x.Pack.Id).ToList(); ``` I get the error: Cannot implicitly convert type 'Data.Entities.Pack' to 'bool' How can I solve this? What should I change in my Include() method?

Original source