Question

Consider the following Query :

var profilelst =
    (
        from i in dbContext.ProspectProfiles
        where i.CreateId == currentUser
        select new ProspectProfile
        {
            ProspectId = i.ProspectId,
            Live = i.Live,
            Name = i.Name,
            ServiceETA = i.Opportunities.OrderByDescending(t => t.FollowUpDate)
                .FirstOrDefault()
                .ServiceETA.ToString(),
            FollowUpDate = i.Opportunities.OrderByDescending(t => t.FollowUpDate)
                .FirstOrDefault()
                .FollowUpDate
        }
    )
    .ToList();

return profilelst.OrderByDescending(c=>c.FollowUpDate)
        .Skip(0).Take(endIndex)
        .ToList();

Here in this query please take a look at FollowUpDate and ServiceType, these both i have fetched from Opportunity table, is there any other work around to get these both..

One to Many Relationship in tables is like: ProspectProfile -> Opportunities

Whether the query i have written is ok or is there any another work around that can be done in easier way.

Answer 1

The only thing you can improve is to avoid ordering twice by changing your code to this:

var profilelst
  = dbContext.ProspectProfiles
             .Where(i => i.CreateId == currentUser)
             .Select(i => 
                    {
                        var opportunity
                           = i.Opportunities
                              .OrderByDescending(t => t.FollowUpDate)
                              .First();
                        return new ProspectProfile
                        {
                            ProspectId = i.ProspectId,
                            Live = i.Live, 
                            Name = i.Name,
                            ServiceETA = opportunity.ServiceETA.ToString(),
                            FollowUpDate = opportunity.FollowUpDate
                        }
                    }).ToList();

return profilelst.OrderByDescending(c => c.FollowUpDate).Take(endIndex).ToList();

I made several changes to your original query:

1. I changed it to use method chains syntax. It is just so much easier to read in my opinion.
2. I removed the unnecessary Skip(0).
3. The biggest change is in the Select part:
   1. I changed FirstOrDefault to First, because you are accessing the properties of the return value anyway. This will throw a descriptive exception if no opportunity exists. That’s better than what you had: In your case it would throw a NullReferenceException. That’s bad, NullReferenceExceptions always indicate a bug in your program and are not descriptive at all.
   2. I moved the part that selects the opportunity out of the initializer, so we need to do the sorting only once instead of twice.