Question

I am using the following code to first check if a string is located somewhere within a column in my database. If it is, I am then needing to check if a few additional criteria are met by looking at different parts of the database (can be seen in the code below). I am not sure if this is an efficient method for doing this or if there is a much simpler way:

(from my Controller)

    [HttpPost]
    public ActionResult Index(FormCollection sampleKey)
    {
        string code = sampleKey["sampleCode"];
        ViewBag.code = code;
        // Need to check if this code is active
        var order = db.Orders.SingleOrDefault(
            o => o.OrderCode == code
                && o.Active == true);
        if (order == null)
        {
            //Invalid
        }
        else
        {
            var orderIdent = db.OrderDetails.SingleOrDefault(
                p => p.OrderDetailId == order.OrderId);
            var barIdent = db.Drink.SingleOrDefault(
                q => q.EstablishmentsID == orderIdent.DrinksId);
            var barName = db.Establishment.SingleOrDefault(
                r => r.EstablishmentsId == barIdent.EstablishmentsID);
            ViewBag.barId = barName.name;
            ViewBag.sample = order.Email;
            var custProfile = CustomProfile.GetUserProfile();
            if (custProfile.OwnedBar != barName.name)
            {
                //Not a match
            }
            else
            {
                //Match
            }
        }
        return View();
    }

Is this something to worry about? Is there a more efficient way of performing the actions that I am currently performing? Should I change the first table that is referenced to include data from the table I ultimately compare it to to avoid what seems to be an inefficient way of comparing information from different tables?

Answer 1

You should check the SQL query that gets generated. You can do that by e.g. outputting the queries to the console, which is done by setting db.Log = Console.Out;. There should be a similar method to output to the web page in your case. The lazy nature of LINQ makes things difficult to predict.

Other than that, you could make your life much easier if you create foreign key relationships between your tables, i.e. OrderDetails has Orders.OrderId as a FK. This will allow Entity Framework to generate navigational properties for your database. With them your code would look like this:

[HttpPost]
public ActionResult Index(FormCollection sampleKey)
{
    string code = sampleKey["sampleCode"];

    var detail = db.Orders.Where(o => o.OrderCode == code && o.Active == true)
        .Select(o => new { 
            OrderCode = o.OrderCode,
            BarId = o.Drink.Establishment.Select(n => n.name),
            Sample = o.Email
            })
        .SingleOrDefault();

    if (detail != null)
    {
        ViewBag.code = detail.OrderCode;
        ViewBag.barId = detail.BarId;
        ViewBag.sample = detail.Sample;

        var custProfile = CustomProfile.GetUserProfile();
        if (custProfile.OwnedBar == detail.BarId)
        {
            //Match
        }
        else
        {
            //Not a match
        }
    }
    else
    {
        //Invalid
    }

    return View();
}