Question

在此方法中，根据sql查询显示的结果数量，自动为流布局面板生成按钮。然后将新按钮添加到Eventhandler以获取功能。我的问题是，我想获取特定于我点击的按钮的信息。分配给按钮的信息是clientName，projectType，在后台，包含属性clientNo和projectNo以用于参照完整性。我需要的是单击按钮时分配给该按钮的值。

现在，该方法仅返回创建的最后一个按钮。

private string AddButton()
        {

            string sql = "SELECT projectType, clientName, projectNo, Client.clientNo FROM Project, Client WHERE Project.ClientNo = Client.ClientNo;";

            newConnection = new ConnectToDatabase(sql);

            dataReader = newConnection.NewDataReader();

            while (dataReader.Read())
            {
                newButton = new Button();
                newButton.Font = new Font("Georgia", 12);
                newButton.Size = new Size(194, 80);
                newButton.Name = dataReader.GetValue(3).ToString();
                newButton.Text = dataReader.GetValue(1).ToString() + "\n" + dataReader.GetValue(0);
                flpDisplayProjects.Controls.Add(newButton);
                newButton.Click += new System.EventHandler(newButton_Click);
            }

            return newButton.Name;
        }

        void newButton_Click(object sender, EventArgs e)
        {
            string sql = "SELECT projectType, clientName, projectNo FROM Project, Client WHERE Project.ClientNo = Client.ClientNo AND " +
                "clientName = '" + newButton.Name + "';";

            newConnection = new ConnectToDatabase(sql);

            dataReader = newConnection.NewDataReader();

            timeTrackingForm newForm = new timeTrackingForm(dataReader);
            newForm.Show();
        }

Answer 1

sender参数中提供了触发事件的按钮...只需将其转换回来：

void newButton_Click(object sender, EventArgs e)
{
    Button myButton = (Button)sender;

    // do whatever you want with myButton, not newButton

    ...

不要使用newButton，它只是对您创建的最后一个按钮的引用。实际上，该变量应该在 inside 中定义，无论创建这些按钮的方法是什么。

Answer 2

您可以使用lambda表达式来捕获lambda之外的任何值。

您的代码如下所示：

private string AddButton()
{
    string sql = "SELECT projectType, clientName, projectNo, Client.clientNo FROM Project, Client WHERE Project.ClientNo = Client.ClientNo;";
    newConnection = new ConnectToDatabase(sql);
    dataReader = newConnection.NewDataReader();
    while (dataReader.Read())
    {
        newButton = new Button();
        newButton.Font = new Font("Georgia", 12);
        newButton.Size = new Size(194, 80);
        newButton.Name = dataReader.GetValue(3).ToString();
        newButton.Text = dataReader.GetValue(1).ToString() + "\n" + dataReader.GetValue(0);
        flpDisplayProjects.Controls.Add(newButton);
        newButton.Click += (s, e) =>
        {
            string sql = "SELECT projectType, clientName, projectNo FROM Project, Client WHERE Project.ClientNo = Client.ClientNo AND " +
            "clientName = '" + newButton.Name + "';";
            newConnection = new ConnectToDatabase(sql);
            dataReader = newConnection.NewDataReader();
            timeTrackingForm newForm = new timeTrackingForm(dataReader);
            newForm.Show();
        };
    }
    return newButton.Name;
}

newButton处理程序中对Click的引用与外部相同。

这也消除了创建newButton_Click方法的需要 - 这通常适用于封装功能。

如何从单击事件中获取有关自动生成按钮的特定信息

2 个答案: