Question

I’ve got a Tag object:

public class Tag
{
    public int TagID { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Job> Jobs { get; set; }

    public Tag()
    {
        Jobs = new HashSet<Job>();
    }
}

and extended:

public class RecentTag : Tag
{
    public int Count { get; set; }
}

…and I’m trying to retrieve a list of RecentTag objects with Count from the query added to each object:

public IEnumerable<RecentTag> GetRecentTags(int numberofdays)
{
    var tags = Jobs
        .Where(j => j.DatePosted > DateTime.Now.AddDays(-(numberofdays)))
        .SelectMany(j => j.Tags)
        .GroupBy(t => t, (k, g) => new
        {
            RecentTag = k,
            Count = g.Count()
        })
        .OrderByDescending(g => g.Count);

    // return RecentTags { TagID, Name, Count, Jobs }
}

So, how do I cast results of the query to RecentTag type and return the list of extended objects?

Any help would be appreciated. Thanks in advance!

Answer 1

I ended up doing:

public IEnumerable<RecentTag> GetRecentTags(int numberofdays)
{
    DateTime startdate = DateTime.Now.AddDays(-(numberofdays));

    IEnumerable<RecentTag> tags = Jobs
        .Where(j => j.DatePosted > startdate) // Can't use DateTime.Now.AddDays in Entity query apparently
        .SelectMany(j => j.Tags)
        .GroupBy(t => t, (k, g) => new RecentTag
        {
            TagID = k.TagID,
            Name = k.Name,
            Count = g.Count()
        })
        .OrderByDescending(g => g.Count)
        .Select(a => a);

    return tags;
}