计算asp.net mvc中视图中的项目数

Question

I am very new to asp.net development. In my asp.net mvc project I have model "Employee" and I'm passing a list of "Employee" model to a RAZOR view and I'm trying to count different type of employees and show a summary.

my view is like this,

@{
    int available = 0;
    int onLeave = 0;
    int away = 0;
    int unAvailable = 0;
}

@foreach (var employee in Model){
  <lable>@employee.Name</lable></br>
   @if (@employee.Available){
      @available=available+1;
  }
   @if (@employee.Unavailable){
      @unAvailable=unAvailable;
  }
   @if (@employee.Away){
      @away=away+1;
  }
   @if (@employee.Onleave){
       @onLeave=onLeave+1;
  }

}
    <div>
        <!--additional summary is displayed here-->
        <label>Available:</label>@available
        <label>Unavailable:</label>@unAvailable
        <label>Away:</label>@away
        <label>On Leave:</label>@onLeave
    </div>

but when I run the my project variables "available","unAvailable","away" and "onLeave" don't get updated.

I'm sure that list is not empty because employee names are displaying. can some explain me what is happening here and correct way of doing this

Answer 1

You should be doing this outside the before passing to the view like I mentioned in my original comment. You can create a new object called a ViewModel to represent the data exactly like you want it on the page. So I created a simple example, I only used the 4 properties of Employee you are displaying in you CSHTML page. On your View where you said your MODEL is either a list, arrary or whatever of Employee change it to EmployeeViewModel. Then in your controller where you get your list of employees set them to the Employees property of the Employee ViewModel.

public class EmployeeViewModel
{
    public IEnumerable<Employee> Employees { get; set; }
    public int TotalAvailable { get { return Employees.Count(emp => emp.Available); } }
    public int TotalUnavailable { get { return Employees.Count(emp => emp.Unavilable); } }
    public int TotalAway { get { return Employees.Count(emp => emp.Away); } }
    public int TotalOnLeave { get { return Employees.Count(emp => emp.OnLeave); } }

}

public class Employee
{
    public bool Available { get; set; }
    public bool Unavilable { get; set; }
    public bool Away { get; set; }
    public bool OnLeave { get; set; }
}

//In the controller do this.
public ActionResult Index() //use your controller Action Name here
{
    var employeeViewModel = new EmployeeViewModel { Employees = /*Your list of empoyees you had as a Model before here*/}
    return View(employeeViewModel)
}

Change your CSHTML code to something like this:

@foreach(var employee in Model.Employees)
{
  <label> @employee.Name </label></br>
}
    <div>
        <!--additional summary is displayed here-->
        <label> Available:</label> @Model.TotalAvailable
        <label> Unavailable:</label> @Model.TotalUnavailable
        <label> Away:</label> @Model.TotalAway
        <label> On Leave:</label> @Model.TotalOnLeave
    </div>

Answer 2

Mvc sample on how to do it:

you need a model class

public class EmployeeModel
{
        public int Available {get; set;}
        public int OnLeave  {get; set;}
        public int Away {get; set;}
        public int UnAvailable  {get; set;}
}

and a command:

  public ActionResult Index()
  {
    var model = new EmployeeModel();
    model.Available = employee.count(e=> e.available);
    model.OnLeave = employee.count(e=> e.onLeave);
    model.Away = employee.count(e=> e.away);
    model.UnAvailable = employee.count(e=> e.unAvailable );
    return View(model);
  }

and a view

@model EmployeeModel
   <div>
        <!--additional summary is displayed here-->
        <label>Available:</label>@Model.Available
        <label>Unavailable:</label>@Model.UnAvailable
        <label>Away:</label>@Model.Away
        <label>On Leave:</label>@Model.OnLeave
   </div>

Answer 3

An easy and quick way is:

<div>
    <!--additional summary is displayed here-->
    <label>Available:</label>@Model.Count(i => i.Available)<br>
    <label>Unavailable:</label>do the same.
    <label>Away:</label>do the same.
    <label>On Leave:</label>do the same.
</div>

Make sure the model has already been "ToList()", or it might lead to mult-access of database.

Basically, I only use viewmodel when I need to pass more than 1 models to the view. Not worth in this case.

Answer 4

Make such calculations in View considered a BAD practice .

In your case better option will be create ViewModel with corresponding properties and then pass it to the model, previously calculating count for every type in controller using LINQ. Where you could reference your types like Model.available, Model.away and so on. Using ViewModel it is the best practice for MVC.

@Thorarins answer show you how to use LINQ in your code to calculate count for you types.

UPDATE: You can use JS, but you should not, because it still not what supposed to happen in View. Work with data should not be handled in View. Don't be scared by ViewModels, they not that hard as it could seem. Please read this article which consider all ways to pass data to View, which has good example how create and pass ViewModel.