Question

我遇到了与此问题相同的问题：TextBox, Button and ListBox in a ListBox

所以我接受了@Andy的回答，但它给了我麻烦：

private void ButtonAddNewTask_Click(object sender, RoutedEventArgs e)
{
    Button btn = (Button)sender;
                IssueView curIssue = (Issue)btn.DataContext;
                if (curIssue != null)
                {
                    curIssue.Issue.Comments.Add(new Comment()
                    {
                        Commentary = curIssue.NewCommentName
                    });
                }
}

我想知道这是不是我的错误，如果帖子太旧或@Andy遗忘了什么而且我无法得到什么，我也没有很好地适应我的代码。

修改我的课程和改编的按钮点击事件

public sealed class Issue
{
    public string Name { get; set; }
    public string Detail { get; set; }

    private ObservableCollection<Comment> comments =
    new ObservableCollection<Comment>();
    public IList<Comment> Comments
    {
        get { return comments; }
    }
}

public sealed class Comment
{

    // string AssociatedIssue { get; set; }
    public string Commentary { get; set; }
}

class IssueView : INotifyPropertyChanged
{
    public Issue Issue { get; set; }

    private string newCommentName = string.Empty;

    public string NewCommentName
    {
        get { return newCommentName; }
        set
        {
            newCommentName = value;
            OnPropertyChanged("NewCommentName");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string propName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));
    }
}

}

Answer 1

// Types at the beginning and end of this statement should be the same
ProjectView curProject = btn.DataContext as ProjectView;

Answer 2

您需要在ProjectView变量（而不是Project）中存储ProjectView。

 ProjectView curProject = (btn.DataContext as ProjectView);

如果DataContext永远不能转换为ProjectView，那么curProject将始终为null。

Answer 3

你能这样试试吗？：

private void ButtonAddNewTask_Click(object sender, RoutedEventArgs e)
{
Button btn = (Button)sender;
ProjectView curProject = (Project) btn.DataContext;
if(null != curProject)
    {
    curProject.Project.Tasks.Add(new Task()
        {
        Name = curProject.NewTaskName
        });
    }
}

您是如何尝试将项目转换为ProjectView的？看来，它们是两个不同的类，没有任何继承。

无法将类类隐式转换为类

3 个答案: