如何将用户控件（视图）中的逻辑剥离到演示者

Posted 2023-02-26

【中文标题】如何将用户控件（视图）中的逻辑剥离到演示者

【英文标题】：How can I strip out logic from a UserControl (View) to the Presenter

【发布时间】：2015-09-23 18:04:25

【问题描述】：

这是我第一次尝试让 MVP 与 WinForms 一起工作。我确实有一个更大的项目。但是，在这里我对 WinForms MVP 示例进行了非常简单的尝试。我只有一个模型、一个表单和两个视图。演示者在 Program.cs 中连接。一切正常。但是，对于一个特定的用户控件，我似乎无法将其余的业务逻辑重构到 Presenter 中。我正在尝试制作一个易于修改为演示项目的示例。我真的不是在寻找简单的让它工作，而是我在寻找“经典”的答案，如果有这样的事情。感谢您提供的任何帮助或建议。即使是朝着正确的方向推动也会有很大的帮助。

我的 MainFormPresenter：

internal class MainFormPresenter

    private readonly SimpleContext _context = new SimpleContext();
    private readonly IMainFormView _mainFormView;
    private readonly IPeopleListView _peopleListView;
    private readonly IPersonInfoView _personInfoView;

    public MainFormPresenter(IMainFormView mainFormView)
    
        _peopleListView = mainFormView.PeopleListView;
        _personInfoView = mainFormView.PersonInfoView;

        _mainFormView = mainFormView;
        mainFormView.Load += MainFormViewOnLoad;
        mainFormView.FormClosed += MainFormViewOnFormClosed;

        _peopleListView.SelectionChanged += OnSelectedNameChanged;
    

    private void OnSelectedNameChanged(object sender, EventArgs e)
    
        int id = _peopleListView.GetSelectedId();
        Person person = _context.People.Find(id);

        _personInfoView.SetFirstName(person.FirstName);
        _personInfoView.SetLastName(person.LastName);
        _personInfoView.SetBirthDate(person.BirthDate);
    

    private void MainFormViewOnFormClosed(object sender, FormClosedEventArgs e)
    
        _context.Dispose();
    

    private void MainFormViewOnLoad(object sender, EventArgs e)
    
        _context.People.Load();

        BindingList<Person> people = _context.People.Local.ToBindingList();

        _peopleListView.SetDataSource(people);
    

我的 PeopleListView 的代码隐藏：

public partial class PeopleListView : UserControl, IPeopleListView

    private readonly BindingSource _bSource;

    public PeopleListView()
    
        _bSource = new BindingSource();
        InitializeComponent();
    

    public int GetSelectedId()
    
        DataGridViewRow row = PeopleGridView.CurrentRow;

        if (row != null)
        
            Person person = (Person)row.DataBoundItem;
            return person.PersonId;
        

        return 0;
    

    public void SetDataSource(BindingList<Person> people)
    
        _bSource.DataSource = people;
        _bSource.RaiseListChangedEvents = true;

        PeopleGridView.AutoGenerateColumns = false;
        PeopleGridView.DataSource = _bSource;
    

    private void PeopleGridView_SelectionChanged(object sender, EventArgs e)
    
        SelectionChanged?.Invoke(new object(), new EventArgs());
    

    public event EventHandler SelectionChanged;

现在如何将这个逻辑提取回 Presenter？ MVP 模式（根据 Pluralsight 的 - Windows Forms Best Practices）声明视图不应该关心它显示的数据。例如关注点分离。但我希望我的视图在模型更改时更新。

【参考方案1】：

这可能不是佳能，但我是这样处理的。建设性的批评仍然非常受欢迎。简单地说，只是称我为无思想的白痴或告诉我我做错了什么也是找到的。

我修改后的 Presenter：

internal class MainFormPresenter

    private readonly SimpleContext _context = new SimpleContext();
    private readonly IMainFormView _mainFormView;
    private readonly IPeopleListView _peopleListView;
    private readonly IPersonInfoView _personInfoView;

    public MainFormPresenter(IMainFormView mainFormView)
    
        _peopleListView = mainFormView.PeopleListView;
        _personInfoView = mainFormView.PersonInfoView;

        _mainFormView = mainFormView;
        _mainFormView.Load += MainFormViewOnLoad;
        _mainFormView.FormClosed += MainFormViewOnFormClosed;

        _peopleListView.SelectionChanged += OnSelectedNameChanged;
    

    private void OnSelectedNameChanged(object sender, EventArgs e)
    
        DataGridViewRow row = _peopleListView.GetSelectedRow();
        Person person = (Person) row.DataBoundItem;

        _personInfoView.SetFirstName(person.FirstName);
        _personInfoView.SetLastName(person.LastName);
        _personInfoView.SetBirthDate(person.BirthDate);
    

    private void MainFormViewOnFormClosed(object sender, FormClosedEventArgs e)
    
        _context.Dispose();
    

    private void MainFormViewOnLoad(object sender, EventArgs e)
    
        _context.People.Load();

        BindingList<Person> people = _context.People.Local.ToBindingList();

        BindingSource bSource = new BindingSource
        
            DataSource = people,
            RaiseListChangedEvents = true
        ;

        _peopleListView.SetDataSource(bSource);
    

我修改的用户控件（视图）：

public partial class PeopleListView : UserControl, IPeopleListView

    public PeopleListView()
    
        InitializeComponent();
    

    public DataGridViewRow GetSelectedRow()
    
        return PeopleGridView.CurrentRow;
    

    public void SetDataSource(BindingSource bSource)
    
        PeopleGridView.AutoGenerateColumns = false;
        PeopleGridView.DataSource = bSource;
    

    private void PeopleGridView_SelectionChanged(object sender, EventArgs e)
    
        SelectionChanged?.Invoke(new object(), new EventArgs());
    

    public event EventHandler SelectionChanged;