asp.net - 如何使用 MVP 在 GridView 中绑定(bind)数据并对其进行操作

Question

我对 MVP 的事情还很陌生，并且正在慢慢地了解这一切。我遇到的问题是如何在填充 GridView(和 ddls，但我们稍后会解决这个问题)时与 MVP 方法保持一致。

可以将其直接连接到 ObjectDataSourceID 吗？对我来说，这似乎是错误的，因为它绕过了 MVP 所做的所有关注点分离。

话虽如此，我该怎么做呢？如何处理排序(是否将处理程序事件发送到表示层，如果是的话，在代码中看起来如何)？现在我有一个没有排序的 GridView。代码如下。

ListCustomers.aspx.cs:

public partial class ListCustomers : System.Web.UI.Page, IlistCustomer
{
protected void Page_Load(object sender, EventArgs e)
{
    //On every page load, create a new presenter object with
    //constructor  recieving the 

    //  page's IlistCustomer view 
    ListUserPresenter ListUser_P = new ListUserPresenter(this);

    //Call the presenter's PopulateList to bind data to gridview
    ListUser_P.PopulateList();

}

GridView IlistCustomer.UserGridView
{
    get { return gvUsers; }
    set { gvUsers = value; }
}

}

接口(interface)(IlistCustomer.cs):在整个 Gridview 控件中发送是否错误？

public interface IlistCustomer
{
GridView UserGridView { set; get; }
}

演示者(ListUserPresenter.cs):

public class ListUserPresenter
{
private IlistCustomer view_listCustomer;
private GridView gvListCustomers;
private DataTable objDT;

public ListUserPresenter( IlistCustomer view)
{
    //Handle an error if an Ilistcustomer was not sent in)
    if (view == null)
        throw new ArgumentNullException("ListCustomer View cannot be blank");

    //Set local IlistCustomer interface view
    this.view_listCustomer = view;
}

public void PopulateList()
{
    //Fill local Gridview with local IlistCustomer
    gvListCustomers = view_listCustomer.UserGridView;

    // Instantiate a new CustomerBusiness object to contact database
    CustomerBusiness CustomerBiz = new CustomerBusiness();

    //Call CustomerBusiness's GetListCustomers to fill DataTable object
    objDT = CustomerBiz.GetListCustomers();

    //Bind DataTable to gridview;
    gvListCustomers.DataSource = objDT;
    gvListCustomers.DataBind();
}
}

Answer 1

我将首先强调 MVP 作为模式解决的主要问题。首先是通过关注点分离来实现模块化。这意味着理想情况下可以将 View 层从 Web 窗体更改为 Windows 窗体，而无需更改 Presenter 层和模型层中的任何内容。其次，使用 MVP 设计的应用程序很容易进行单元测试，因为测试表单非常困难。考虑到这一点，您就会意识到不应在 Presenter 层中操作以 View 为中心的对象(例如网格)，因为当 View 更改时，控件也可能会更改。为了回答您的问题，我可以通过以下方式解决您的问题:

// View
public interface IListCustomersView
{
    public void BindGrid(IList<Customer> customers);
}

// Form e.g. Web Form, Windows Form
public class ListCustomers : IListCustomersView
{
    private ListCustomersPresenter listCustomerPresenter = null;

    public ListCustomers()
    {
        // You can use a Dependency Injector here
        this.listCustomersPresenter = new ListCustomerPresenter(
            new CustomerRepository(),
            this);
    }

    public void BindGrid(IList<Customer> customers)
    {
            grid.DataSource = customers;
            grid.Databind();
    }
}

// Presenter
public class ListCustomersPresenter
{
    private readonly IListCustomersView view = null;
    private readonly ICustomerRespository repository = null;

    public ListCustomersPresenter(
         ICustomerRespository  customerRepository, IListCustomersView view)
    {
        Guard.AgainstNull(view,"View");
        Guard.AgainstNull(customerRepository,"CustomerRepository");

        this.view = view;
        this.customerRepository = customerRepository;
    }

    public void BindGrid()
    {
         // Fetch customers from repository
         IList<Customer> customers = this.customerRepository.GetCustomers();
         view.BindGrid(customers);          
    }
}