Razor View Flow - asp.net-mvc

Question

Having a brain fart... given this model:
public class Result
{
public decimal Cost {get;set;}
}
And this extreme simplified view:
#{
decimal resultsTotal = 0;
}
<div>#resultsTotal</div> //need the total from the loop below here
#foreach(var result in Model.Results)
{
resultsTotal += result.Cost;
<div>#result.Cost</div>
}
I need to display the resultsTotal variable above the foreach loop. I realize I can #Model.Results.Sum(x => x.Cost) in the view, the model or the controller, the point is I want to avoid enumerating Results more than once. Is there away to buffer the results and update the div after looping through perhaps or? Yea I could also use jquery, but that smells.

Answer 1

You could use a helper and write the results to a buffer:
#{
IEnumerable<Result> results = Model.Results;
decimal resultsTotal = 0;
var buffer = new List<HelperResult>();
}
#foreach(var result in Model)
{
resultsTotal += result.Cost;
buffer.Add(ResultRow(result))
}
<div>#resultsTotal</div>
#foreach (var result in buffer)
{
#result
}
#helper ResultRow(Result result)
{
<div>#result.Cost</div>
}

Answer 2

#{
IEnumerable<Result> results = Model.Results;
#foreach(var result in Model=)
{
<div>#result.Cost</div>
}
var resultsTotal = Model.Results.Sum(x => x.Cost)
}
<div>#resultsTotal</div>
#{} is a code block that you can use to execute code. I wouldn't recommend doing it this way, as putting logic in the view is just down right dirty.
You should make this calculation within your controller's action method and pass it to your view via the model.
Something along the lines of this...
public ActionResult Index()
{
// ... get your results from wherever you got them from before, eg your service ...
IEnumerable<Result> results = myService.GetResults();
decimal resultsTotal = 0;
var responseModel = new YourViewModel
{
Results = results,
ResultsTotal = results.Sum(x => x.Cost)
};
return View(responseModel);
}
And then you can display the information that has been calculated already within your controller on the view, with a minimal amount of logic:
#foreach(var result in Model.Results)
{
<div>#result.Cost</div>
}
<div>#Model.ResultsTotal</div>

Answer 3

Move the logic out of your view and into your view model. Unfortunately, you haven't made very clear what type of calculations you're desiring to make, but, in general, just add properties on your view model(s) that return the results of those calculations and you can chain them if need be. For example:
public class MyAwesomeViewModel
{
public List<Result> Results { get; set; }
public decimal Total
{
get { return Results.Sum(x => x.TotalCost);
}
public decimal AverageCost
{
get { return Total / Results.Count(); }
}
}
public class ResultViewModel
{
public decimal TotalCost
{
get { return Cost + Tax + Shipping; }
}
}
Much as your example, I've just made up some stuff here to illustrate the point. Break down your calculations into discreet units and then build them back up. This not only simplifies the calculations, but also gives you access to component calculations, should you need them. Then, you can keep your view relatively logic free.