MVC 如何将业务逻辑与 ASP.NET MVC 中的 UI 分开？

Question

I'm a beginner in ASP.NET MVC and Design Pattern. still struggling to understand how MVC separate business logic from UI/View.

Let's say we have this scenario:

There is an Employee model with a property of TotalSales for the total sales of this month, and there is also an default Index view.

so in the view, razor engine should populate employee's details such as name, gender, department etc. So we just need to pass a view model to the view, which seems to be working well. But let's say I want to the UI/HTML also display an extra paragraph "This employee is a good employee" if the employee's TotalSales > 10000 this month, otherwise display "This employee needs to improve his marketing skill". So in the view template, I have to code like this:

@if (employeeInstance.TotalSales > 10000)
{
    <p>This employee is a good employee</p>
}else
{
    <p>This employee needs to improve his marketing skill</p>
}

but isn't the the business logic is mixed inside the view, which is against the goal of MVC pattern?

Answer 1

you can use your logic in model. like if you have model like below

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public double TotalSales { get; set; }
    public string Comment
    {
        get
        {
            if (TotalSales > 10000)
            {
                return "This employee is a good employee";
            }
            else
            {
                return "This employee needs to improve his marketing skill";
            }
        }
    }
}

now you can use Comment property in your view

<p>@Model.Comment</p>

also you can set this employee in your business layer and bind this to your view model and use in your view so using this you can separate your business logic from your view and not required to set your logic in controller. let me know if require more information :).

Answer 2

Do logic in Controller by return ViewBag (or you return ViewModel)

Controller

if (employeeInstance.TotalSales > 10000){
    ViewBag.employeetext = "This employee is a good employee";
}
else{
    ViewBag.employeetext = "This employee needs to improve his marketing skill";
}

View

<p>@ViewBag.employeetext</p>