丢失动态创建的文本框值

本文关键字：文本 创建 动态 | 更新日期: 2023-09-27 18:19:49

请参阅以下代码：

    protected void btnAddField_click( Object sender, EventArgs e ) {
        int FieldCount = 0;
        if (ViewState["FieldCount"] != null)
        {
            FieldCount = (int)ViewState["FieldCount"];
        }
        Table tbl = new Table();
        if (Session["DynamicTable"] != null)
        {
            tbl = (Table)Session["DynamicTable"];
        }
        CheckBox chkNewField = new CheckBox();
        chkNewField.ID = "chkNewField" + FieldCount.ToString();
        chkNewField.Checked = true;
        Label LblNewLabel = new Label();
        LblNewLabel.ID = "lblNewLabel" + FieldCount.ToString();
        LblNewLabel.Text = "New Lable";
        TextBox TxtNewLabel = new TextBox();
        TxtNewLabel.ID = "TxtNewLabel" + FieldCount.ToString();
        Label LblNewValue = new Label();
        LblNewValue.ID = "lblNewValue" + FieldCount.ToString();
        LblNewValue.Text = "New Value";
        TextBox TxtNewValue = new TextBox();
        TxtNewValue.ID = "TxtNewValue" + FieldCount.ToString();
        TableRow tRow = new TableRow();
        TableCell tCell1 = new TableCell();
        TableCell tCell2 = new TableCell();
        tCell2.Attributes.Add("class", "medium");
        TableCell tCell3 = new TableCell();
        tCell3.Attributes.Add("class", "medium");
        TableCell tCell4 = new TableCell();
        TableCell tCell5 = new TableCell();
        tCell5.Attributes.Add("class", "medium");
        TableCell tCell6 = new TableCell();
        tCell6.Attributes.Add("class", "medium");
        tCell1.Controls.Add(chkNewField);
        tCell2.Controls.Add(LblNewLabel);
        tCell3.Controls.Add(TxtNewLabel);
        tCell4.Controls.Add(new LiteralControl(""));
        tCell5.Controls.Add(LblNewValue);
        tCell6.Controls.Add(TxtNewValue);
        tRow.Cells.Add(tCell1);
        tRow.Cells.Add(tCell2);
        tRow.Cells.Add(tCell3);
        tRow.Cells.Add(tCell4);
        tRow.Cells.Add(tCell5);
        tRow.Cells.Add(tCell6);
        tbl.Rows.Add(tRow);
        placeHolderTable.Controls.Remove(tbl);
        placeHolderTable.Controls.Add(tbl);
        Session["DynamicTable"] = tbl;
        FieldCount++;
        ViewState["FieldCount"] = FieldCount;
}
protected void BtnPublish_click( object sender, EventArgs e ) { 
   TextBox tb = (TextBox)placeHolderTable .FindControl( "TxtNewLabel1" ); 
}

动态添加字段运行良好。但是

  1. 我在文本框中输入的值在每回帖子中都会被清除
  2. 我未能从文本框中获取值

请帮帮我。提前感谢，Manu

丢失动态创建的文本框值

尽管有一种棘手的方法可以在PostBack中获取文本框的值。您可以在下面使用此代码。

private string GetValue(string ControlID)
{
     string[] keys = Request.Form.AllKeys;
     string value = string.Empty;
     foreach (string key in keys)
     {
         if (key.IndexOf(ControlID) >= 0)
         {
             value = Request.Form[key].ToString();
             break;
         }
     }
     return value;
}

然后在PostBack中使用此方法。

protected void BtnPublish_click( object sender, EventArgs e ) 
{ 
    string TxtNewLabel1Val = GetValue("TxtNewLabel1");
}

关于动态创建控件的简单规则是，如果要接收任何值，则必须在Init上重新创建它们。

参考：页面生命周期

Postback数据在函数ProcessPostData中进行处理。如果在此之前没有创建控件，则不会分配用户输入。

我会将控件创建放入一个方法中，跟踪在会话（或ViewState）中添加动态控件的情况，并在之后的每个Init上添加它们，直到我希望控件出现在页面上。

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