如何在视图状态中为搜索功能保留动态生成的web控件输入

你不需要重写SaveViewState/LoadViewState。但是你必须在ViewState中保留选择来创建postback上的控件。这应该可以工作:

internal enum DataType
{
    None = 0,
    Decimal
}
internal enum Operator
{
    Equal,
    GreaterThan,
    None
}
public partial class _Default : Page
{
    private DataType DataType
    {
        get
        {
            object dataType = ViewState["DataType"];
            if (dataType != null) return (DataType)dataType;
            return DataType.None;
        }
        set { ViewState["DataType"] = value; }
    }
    private int? DataTypeIndex
    {
        get { return ViewState["DataTypeIndex"] as int?; }
        set { ViewState["DataTypeIndex"] = value; }
    }
    private Operator Operator
    {
        get
        {
            var @operator = ViewState["Operator"];
            if (@operator != null)
                return (Operator)@operator;
            return Operator.None;
        }
        set { ViewState["Operator"] = value; }
    }
    private void BindDropDownLists()
    {
        column_list_for_filter.ConnectionString = connection;
        string item = "--Select--";
        column_list_for_filter.SelectCommand = "SELECT DATA_TYPE + '_' + convert(varchar(10), ROW_NUMBER() OVER(ORDER BY DATA_TYPE))as DATA_TYPE, COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE (TABLE_NAME = 'RESULT' AND COLUMN_NAME IN ('Column1','Column2','Column3','Column4'))";
        DropDownList5.DataTextField = "COLUMN_NAME";
        DropDownList5.DataValueField = "DATA_TYPE";
        DropDownList5.DataBind();
        DropDownList5.Items.Insert(0, item);
    }
    protected void DropDownList5_SelectedIndexChanged(object sender, EventArgs e)
    {
        DataTypeIndex = DropDownList5.SelectedIndex;
        if (DropDownList5.SelectedValue.Contains("decimal"))
        {
            DataType = DataType.Decimal;
        }
        CreateDataTypeControl();
        //else if (DropDownList5.SelectedValue.Contains("varchar"))
        //{
        //DataType = DataType.Varchar;
        //}
        //else if (DropDownList5.SelectedValue.Contains("datetime"))
        //{
        //DataType = DataType.DateTime;
        //}
        //else if (DropDownList5.SelectedValue.Contains("int"))
        //{
        //DataType = DataType.Integer;
        //}
    }
    protected void Range_DDL_Decimal_SelectedIndexChanged(object sender, EventArgs e)
    {
        var ddl = (DropDownList)sender;
        switch (ddl.SelectedIndex)
        {
            case 1:
                Operator = WebApplication1.Operator.Equal;
                break;
        }
        CreateRangeControls();
    }
    protected void createdynamiccontrols_decimal()
    {
        int i = DataTypeIndex.GetValueOrDefault();
        ++i;
        TableRow row = new TableRow();
        row.ID = "TableRow_";
        TableCell cell1 = new TableCell();
        cell1.ID = "TableCell_";
        DropDownList Range_DDL_Decimal = new DropDownList();
        Range_DDL_Decimal.ID = "RandeDDL_Decimal" + i.ToString();
        Range_DDL_Decimal.Items.Insert(0, new ListItem("--Select--", "--Select--"));
        Range_DDL_Decimal.Items.Insert(1, new ListItem("Equal", "Equal"));
        Range_DDL_Decimal.Items.Insert(2, new ListItem("NotEqual", "NotEqual"));
        Range_DDL_Decimal.Items.Insert(3, new ListItem("greater than", "greater than"));
        Range_DDL_Decimal.Items.Insert(4, new ListItem("lesser than", "lesser than"));
        Range_DDL_Decimal.Items.Insert(5, new ListItem("greater than or equal to", "greater than or equal to"));
        Range_DDL_Decimal.Items.Insert(6, new ListItem("lesser than or equal to", "lesser than or equal to"));
        Range_DDL_Decimal.Items.Insert(7, new ListItem("Contains", "Contains"));
        Range_DDL_Decimal.Items.Insert(8, new ListItem("Is Null", "Is Null"));
        Range_DDL_Decimal.Items.Insert(9, new ListItem("Is Not Null", "Is Not Null"));
        Range_DDL_Decimal.Items.Insert(10, new ListItem("Between", "Between"));
        Range_DDL_Decimal.SelectedIndexChanged += new System.EventHandler(Range_DDL_Decimal_SelectedIndexChanged);
        Range_DDL_Decimal.AutoPostBack = true;
        cell1.Controls.Add(Range_DDL_Decimal);
        //// Add the TableCell to the TableRow  
        row.Cells.Add(cell1);
        dynamic_filter_table.Rows.Add(row);
        dynamic_filter_table.EnableViewState = true;
        ViewState["dynamic_filter_table"] = true;
    }
    protected void CreateRangeTextBoxes()
    {
        int j = DataTypeIndex.GetValueOrDefault();
        ++j;
        TableCell cell2 = new TableCell();
        cell2.ID = "Range";
        TextBox tb1 = new TextBox();
        TextBox tb2 = new TextBox();
        Label lbl1 = new Label();
        Label lbl2 = new Label();
        // Set a unique ID for each TextBox added      
        tb1.ID = "lowerbound_" + j.ToString();
        tb2.ID = "upperbound_" + j.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";
        cell2.Controls.Add(lbl1);
        cell2.Controls.Add(tb1);
        cell2.Controls.Add(lbl2);
        cell2.Controls.Add(tb2);
        TableRow rowtwo = dynamic_filter_table.FindControl("TableRow_") as TableRow;
        rowtwo.Cells.Add(cell2);

        dynamic_filter_table.Rows.Add(rowtwo);
        dynamic_filter_table.EnableViewState = true;
        ViewState["dynamic_filter_table"] = true;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        int j = DropDownList5.SelectedIndex;
        ++j;
        Panel6.Visible = true;
        JQGrid9.Visible = true;
        Find Control not working
        TextBox lowerboundd = dynamic_filter_table.FindControl("lowerbound_" + j.ToString()) as TextBox;
        TextBox upperbound = dynamic_filter_table.FindControl("upperbound_" + j.ToString()) as TextBox;
        DropDownList range = dynamic_filter_table.FindControl("RandeDDL_Decimal" + j.ToString()) as DropDownList;
        con.Open();
        SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM RESULT WHERE " + DropDownList5.Text + DDL2.Text + " >= " + lowerboundd.Text + " AND " + DropDownList5.Text + " <= " + upperbound.Text, con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        con.Close();
        Session["DataforSearch"] = ds.Tables[0];
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        Panel6.Visible = false;
        JQGrid9.Visible = false;
        if (Session["DataforSearch"] != null)
        {
            Panel6.Visible = true;
            JQGrid9.Visible = true;
            JQGrid9.DataSource = Session["DataforSearch"] as string;
        }
        CreateDataTypeControl();
        CreateRangeControls();
    }
    void CreateDataTypeControl()
    {
        switch (DataType)
        {
            case DataType.Decimal:
                createdynamiccontrols_decimal();
                break;
        }
    }
    void CreateRangeControls()
    {
        switch (Operator)
        {
            case WebApplication1.Operator.GreaterThan:
            case Operator.Equal:
                CreateRangeTextBoxes();
                break;
        }
    }
}