c# - 从 C# 中以编程方式创建的 TextBox 中获取值

Question

我遇到了这个令人痒痒的问题，但我无法让代码工作

发布表单时如何从 TextBox 读取值？

一些代码...

protected override void CreateChildControls() {

    base.CreateChildControls();

    TextBox queryBox = new TextBox();
    queryBox.ID = "querybox";
    queryBox.ToolTip = "Enter your query here and press submit";
    Controls.Add(queryBox);

    Button queryButton = new Button();
    queryButton.UseSubmitBehavior = false;
    queryButton.ID = "querybutton";
    Controls.Add(queryButton);

    if (Page.IsPostBack == true) {
        try {
            string query = querybox.Text;

            DataGrid dataGrid = new DataGrid();
            dataGrid.DataSource = Camelot.SharePointConnector.Data.Helper.ExecuteDataTable(query, connectionString);
            dataGrid.DataBind();
            Controls.Add(dataGrid);
        } catch (Exception a) {
            Controls.Add(new LiteralControl(a.Message));
        } // try
    } // if
} // void

我稍微缩短了代码，但你看到了这个想法，它的字符串 query = querybox.text 不起作用。我尝试过几种不同的变体，即

TextBox querybox = (TextBox)FindControl("querybox");
string query = querybox.Text;

但是没有...

如有任何提示，我们将不胜感激! 谢谢

Answer 1

问题在于您的控件未填充 CreateChildControls 中 ViewState 的值。我建议在按钮上使用单击事件处理程序。

更新您的按钮代码:

Button queryButton = new Button();
queryButton.UseSubmitBehavior = false;
queryButton.ID = "querybutton";
queryButton.Text = "Query";
queryButton.Click += new EventHandler(queryButton_Click);
Controls.Add(queryButton);

然后，编写点击事件处理程序:

void queryButton_Click(object sender, EventArgs e)
{
    TextBox querybox = this.FindControl("querybox") as TextBox;
    try
    {
         string query = querybox.Text;
         DataGrid dataGrid = new DataGrid();
         dataGrid.DataSource = Camelot.SharePointConnector.Data.Helper.ExecuteDataTable(query, connectionString);
         dataGrid.DataBind();
         Controls.Add(dataGrid);
    }
    catch (Exception a)
    {
         Controls.Add(new LiteralControl(a.Message));
    } // try
}