如何从动态生成文本框输入值 [英] How to retrieve the input values from Dynamically generated TextBoxes
问题描述
我有一个DropDownList界与SqlDataSource的产品清单。随着DropDownList_SelectedIndexchanged（）函数的帮助下，我能够生成两个动态文本框。
I have a DropDownList bounded with list of items from SqlDataSource. With the help of DropDownList_SelectedIndexchanged() function i am able to generate two dynamic text boxes.
所需的输出：我需要寻找根据用户提供的文本框中输入数据和搜索到的数据应当Button_Click（）事件
Required Output: I need to search for the data based on the textbox inputs given by the user and Searched data shall be displayed in JQGrid with the help of Button_Click() event.
当前问题：文本框输入检索不到它总是检索为空字符串
得到的例外是：附近有语法错误和（SQL查询）
Current Issue: The textbox inputs are not retrieved and it always retrieved as null string "". Exception obtained is : Incorrect Syntax near "AND" (SQL Query)
如何解决这个问题？
我的aspx code：
My aspx code:
<asp:Panel ID="Panel5" runat="server" Height="221px">
<span style="font-size: 135%; font-family: Verdana; font-weight: bold"> Search Functionalities </span>
<asp:DropDownList ID="DropDownList5" runat="server" DataSourceID="column_list_for_filter" DataTextField="All_Columns" DataValueField="All_Columns" OnSelectedIndexChanged ="DropDownList5_SelectedIndexChanged" AutoPostBack="true">
</asp:DropDownList>
<asp:SqlDataSource ID="column_list_for_filter" runat="server" ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString %>" SelectCommand="SELECT COLUMN_NAME 'All_Columns' FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='RESULT' "></asp:SqlDataSource>
<asp:Button ID="Button1" runat="server" Font-Bold="True" Font-Names="Arial" Font-Size="Small" OnClick="Button1_Click" Text="Search Flow Periods" Width="144px" />
<asp:Table ID="dynamic_filter_table" runat="server" ToolTip="Results">
</asp:Table>
</asp:Panel>
我的C＃code：
My C# code:
//Creation of Two Dynamic Text Box Web Controls on DDL selection
protected void DropDownList5_SelectedIndexChanged(object sender, EventArgs e)
{
createdynamiccontrols();
}
/*Two Text Boxes and Two Labels for input and search the FlowPeriod and display in JqGrid
thru button click event*/
protected void createdynamiccontrols()//(string ID1, string ID2)
{
int i = DropDownList5.SelectedIndex;
++i;
TableRow row;
row = new TableRow();
TableCell cell1 ;
cell1 = new TableCell();
TableCell cell2;
cell2= new TableCell();
// Set a unique ID for each TextBox added
TextBox tb1;
tb1 = new TextBox();
TextBox tb2;
tb2 = new TextBox();
Label lbl1;
lbl1 = new Label();
Label lbl2;
lbl2 = new Label();
// Set a unique ID for each TextBox added
tb1.ID = "lowerbound_" + i.ToString();
tb2.ID = "upperbound_"+ i.ToString() ;
lbl1.Text = "LowerBound:";
lbl1.Font.Size = FontUnit.Point(10);
lbl1.Font.Bold = true;
lbl1.Font.Name = "Arial";
lbl2.Text = "UpperBound:";
lbl2.Font.Size = FontUnit.Point(10);
lbl2.Font.Bold = true;
lbl2.Font.Name = "Arial";
// Add the control to the TableCell
cell1.Controls.Add(lbl1);
cell1.Controls.Add(tb1);
cell2.Controls.Add(lbl2);
cell2.Controls.Add(tb2);
// Add the TableCell to the TableRow
row.Cells.Add(cell1);
row.Cells.Add(cell2);
dynamic_filter_table.Rows.Add(row);
dynamic_filter_table.EnableViewState = true;
ViewState["dynamic_filter_table"] = true;
Button1.EnableViewState = true;
ViewState["Button_1"] = true;
}
protected override object SaveViewState()
{
object[] viewstate = new object[2];
List<string> dynamic_text_values = new List<string>();
foreach (TableRow row in dynamic_filter_table.Controls)
{
foreach (TableCell cell in row.Controls)
{
if (cell.Controls[1] is TextBox)
{
dynamic_text_values.Add(((TextBox)cell.Controls[1]).Text);
}
}
}
viewstate[0] = dynamic_text_values.ToArray();
viewstate[1] = base.SaveViewState();
return viewstate;
}
protected override void LoadViewState(object savedState)
{
if (savedState is object[] && ((object[])savedState).Length == 2 && ((object[])savedState)[0] is string[])
{
object[] newViewState = (object[])savedState;
string[] txtValues = (string[])(newViewState[0]);
if (txtValues.Length > 0)
{
createdynamiccontrols();
}
base.LoadViewState(newViewState[1]);
}
else
{
base.LoadViewState(savedState);
}
}
protected void Button1_Click(object sender, EventArgs e)
{
createdynamiccontrols();
int j = DropDownList5.SelectedIndex;
++j;
Panel6.Visible = true;
JQGrid9.Visible = true;
TextBox lowerboundd = dynamic_filter_table.FindControl("lowerbound_" + j.ToString()) as TextBox;
TextBox upperbound = dynamic_filter_table.FindControl("upperbound_" + j.ToString()) as TextBox;
string testt = lowerboundd.Text;
con.Open();
SqlDataAdapter da = new SqlDataAdapter("SELECT ColumnName1,Columnname2 FROM RESULT WHERE " + DropDownList5.SelectedValue + " >= " + lowerboundd.Text + " AND " + DropDownList5.SelectedValue + " <= " + upperbound.Text, con);
DataSet ds = new DataSet();
da.Fill(ds);
/*Error occurs here as Incorrect Syntax near AND as the string obtained is "" and not
textbox inputs*/
con.Close();
Session["DataforSearch"] = ds.Tables[0];
}
protected void Page_Load(object sender, EventArgs e)
{
//Dynamic controls creation on Page Load
if (!IsPostBack)
{
BindDropDownLists();
}
dynamic_filter_table.EnableViewState = true;
}
推荐答案
您需要移动 BindDropDownLists（）; 从Page_Load中的Page_Init方法或其他页面的生命周期会找不到视图状态并连接到您的控件。通过你在Page_Load中的时候，你都来不及。确保您的逻辑来创建初始化中的控制和你的逻辑来检索加载/事件中的数据，你应该看到一些成果。
You need to move BindDropDownLists(); to the Page_Init method from Page_Load or else the page lifecycle will not find the viewstate and attach to your controls. By the time you are in Page_Load you are too late. Make sure your logic to create the controls in init and your logic to retrieve the data in load/events and you should see some results.
您不需要视图状态的东西，会自动将自身线了，你不能像点击控制事件创建动态控制或作为的SelectedIndexChanged在生命周期为时已晚，多数民众赞成。动态控件需要加载之前要创建的视图状态来的时候负载接线恶有恶报。
You don't need the viewstate stuff as that will automagically wire itself up, you can't create the dynamic controls in a control event like click or selectedindexchanged as thats too late in the lifecycle. The dynamic controls need to be created before load for the viewstate to be wired by the time load comes around.
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