MVP Winforms 和文本框组合框值

Question

我有一个以列表作为数据源的组合框。此列表包含对象（客户）及其属性（名称、地址...）。当我 select 组合框的一个项目时，我想将信息（地址、邮政编码...）传递到我表单上的一些文本框。在我的测试 1tier 应用程序中，这工作正常。但是我正在处理的主要应用程序是基于 MVP（我自己接触过）。我面临的问题是铸造。由于我的视图不知道我的模型，因此不应允许我使用（客户）。 string address = ((Customers)comboBox1.SelectedItem).CustomerAddress;

1层测试代码：

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    //getCustomers((int)comboBox1.SelectedValue);
    //txtAddress.Text =Convert.ToString( comboBox1.SelectedValue);
    Customers p = (Customers)comboBox1.SelectedItem;
    string s = comboBox1.SelectedItem.ToString();
    string address = ((Customers)comboBox1.SelectedItem).CustomerAddress;
    txtAddress1.Text = address;
}

private void Form3_Load(object sender, EventArgs e)
{
    using (var emp = new EmployerEFEntities())
    {
        var query = from customers in emp.Customers
                    select customers;

        comboBox1.DisplayMember = "CustomerName";
        comboBox1.ValueMember = "CustomerID";
        comboBox1.DataSource = query.ToList();
    }
}

我已经研究了几天了，但还没有成功。我希望有人能给我正确的方向。

实际应用代码：

查看：

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    txtName.Text = comboBox1.SelectedValue.ToString();
}

private void CustomerView_Load(object sender, EventArgs e)
{
    comboBox1.DataSource = customerPresenter.getCustomers();
    comboBox1.DisplayMember = "CustomerName";
    comboBox1.ValueMember = "CustomerId";
}

主持人：

public List<tbl_customer> getCustomers()
{
    using (var customers = new DBCrownfishEntities())
    {
        var customer = from c in customers.tbl_customer
                       select c;

        return customer.ToList();
    }
}

Answer 1

如果您绝对反对让您的视图访问您的域对象——那些代表数据 table 行的对象（在某些情况下可能没问题，具体取决于它们的重量）——您可能想研究使用 DTO。检查底部的 this out for a good description of considerations and one approach to doing it. Note the mention of Automapper。这是一个很棒的工具。

编辑：我刚刚意识到您对 Winforms 解决方案感兴趣，而不是 ASP.NET。虽然上面的 link 涉及 ASP.NET，但 Winforms 应用程序的想法是相同的。

Answer 2

这只是实现它的一种方法。您的 MVP 模式可能看起来不同。在这个实现中，View 知道 Presenter。关于MVP的更多信息你可以看看here

您可以将 Presenter 用作客户的包装器：

public interface IPresenter
{
    void Init();
    void SetSelectedCustomer(int customerId);
    IEnumerable GetCustomers();
    string FirstName { get; set; }
    string LastName { get; set; }
    string Address { get; set; }
}

Presenter 必须实现 INotify属性Changed（并在属性 setter 中调用 On属性Changed）。

public class Presenter : IPresenter, INotifyPropertyChanged
{
    private readonly Repository _repository;
    private string _firstName;
    private string _lastName;
    private string _address;
    private Customer _currentCustomer;

    public Presenter(Repository repository)
    {
        _repository = repository;
    }

    public string FirstName
    {
        get { return _firstName; }
        set
        {
            if (_firstName == value) return;
            _firstName = value;
            OnPropertyChanged();
        }
    }

    public string LastName
    {
        get { return _lastName; }
        set
        {
            if (_lastName == value) return;
            _lastName = value;
            OnPropertyChanged();
        }
    }

    public string Address
    {
        get { return _address; }
        set
        {
            if (_address == value) return;
            _address = value;
            OnPropertyChanged();
        }
    }

    public IEnumerable GetCustomers()
    {
        return _repository.GetAllCustomers();
    }

    public void Init()
    {
        var result = _repository.GetAllCustomers();
        SetSelectedCustomer(result[0].Id);
    }

    public void SetSelectedCustomer(int customerId)
    {
        var customer = _repository.GetCustomerById(customerId);
        FirstName = customer.FirstName;
        LastName = customer.LastName;
        Address = customer.Address;
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

这是视图的样子：

public partial class Form1 : Form
{
    private IPresenter _presenter;
    private bool _initialized;

    public Form1(IPresenter presenter)
    {
        InitializeComponent();           
        _presenter = presenter;
        _presenter.Init();
        SetComboBoxData(_presenter.GetCustomers());
        _initialized = true;
    }

    public void SetComboBoxData(IEnumerable data)
    {
        comboBox1.DataSource = data;
        comboBox1.ValueMember = "Id";
        comboBox1.DisplayMember = "FirstName";
    }

    private void comboBox1_SelectedIndexChanged(object sender, System.EventArgs e)
    {
        if (!_initialized) return;
        _presenter.SetSelectedCustomer((int)comboBox1.SelectedValue);
    }

    private void Form1_Load(object sender, System.EventArgs e)
    {
        textBox1.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.FirstName)));
        textBox2.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.LastName)));
        textBox3.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.Address)));
    }
}

您可以在组合框中的 SelectedIndexChanged 事件中的 Presenter 中设置选定的 CustomerId：

_presenter.SetSelectedCustomer((int)comboBox1.SelectedValue);

Presenter 中的 SetSelectedCustomer 方法（或 SelectedCustomerChanged 事件的事件处理程序）选择具有给定 CustomerId 的客户并设置 FirstName、LastName 和 Address：

public void SetSelectedCustomer(int customerId)
{
    var customer = _repository.GetCustomerById(customerId);
    FirstName = customer.FirstName;
    LastName = customer.LastName;
    Address = customer.Address;
}

您应该对 Form_Load 中的文本框进行绑定：

textBox1.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.FirstName)));
textBox2.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.LastName)));
textBox3.DataBindings.Add(new Binding("Text", _presenter, nameof(_presenter.Address)));

MVP Winforms 和文本框组合框值

MVP Winforms and textbox combobox values

c#

mvp

combobox

winforms