Dynamic ASP.Net Control Creation Using C#.Net

• Download DynamicCreationofASPNETControls.zip - 11.7 KB

Introduction

This artical will teach you how to create the ASP.Net Server controls dynamically and place the controls into the HTML Table which is also created dynamically according to your need.

Landuage

C#.Net

Using the code

Create the ASP.NET Controls and Place it into HTML Tables Dynamically using C#.Net

Step 1

Create a new web project and create a new aspx page ,then create the one html table in the html design as follows

here above i have created the html table in the html design section and i given the name for the table as "myNewTable"

Important : Don't forget make the table as server control and give the visible = false.why because we are going to show the table and the rows and column dynamcally with control

Step 2

Come to the code behind ,I have method called LoadControls() which return the DataTable.Here i used the Layer concept and am using the Orcale as Backend. You can do this without layer concept and you can use SQL instead of Oracle. Make the necessary Database connection for your application before that make sure that you have created the table for this one or not. My sample table structure as follows.

CREATE TABLE TBL_FIELD_CREATION
(
FIELD_ID NUMBER(15,0) NOT NULL,
FIELD_NAME VARCHAR2(100) NULL, // Name for the Control
FIELD_LABEL VARCHAR2(100) NOT NULL, // To Display the Name
FIELD_TYPE VARCHAR2(100) NOT NULL, // Type of the Control like TextBox,DropDown...
STATUS CHAR(1) NOT NULL, // Active or Inactive to Show the control at runtime.
PRIMARY KEY(FIELD_ID)
)

Insert some values into the table for TextBoxes and Dropdownlist boxes.Then Select the Values from the table by writting Inline SQL Query or Stored Procedure according to your need.

//
// Method 1
========
This load control method is a method will return the datatable.
public DataTable LoadControls()
{
try
{
objDt.Clear();
objDt= objMyDl.GetDtValues("T", 0); // Replace your Query or Method which you have written to return the values.

}
catch (CustomException ObjExpCust)
{
MsgBox(ObjExpCust.CustomErrorMessage);
}
catch (Exception)
{
MsgBox("Critical error occured. Unable to process.");
}
return objTrBillandCost;

}
//
//

Step 3

Create an Object for HtmlTableRow and HtmlTableCell.Use Different HtmlTableCell objects for Different column or cell in the HtmlTableRow. You can assign the Style,Color width and height properties for Table,Rows and as well as Cells.

//
Expand code snippet

Method 2
=========
override protected void OnInit(EventArgs e)
    {
        DataTable objDt = LoadControls();
        int row,numrows,numcells,k,l;
        row=0;
        numcells = 4;
        
        if (objDt.Rows.Count > 0)
        {
            
            myNewTable.Border = 0;
            myNewTable.Align = "center";
            
            numrows = objDt.Rows.Count;
            for (k = 1; k <= numrows; k++)
            {
                
                    HtmlTableRow objRow = new HtmlTableRow();
                    row = row + 1;
                    for (l = 1; l <= numcells; l++)
                    {
                        if (l == 1)
                        {
                            HtmlTableCell objCell1 = new HtmlTableCell();
                            objCell1.Align = "right";
                            objCell1.RowSpan = 1;
                            objCell1.ColSpan = 1;
                            objCell1.Width = "100";
                            objCell1.Height = "20";
                            Label lbl = new Label();
                            lbl.ID = "Label" + k.ToString();
                            lbl.CssClass = "LabelLeftSide";
                            lbl.Text = objDt.Rows[k - 1]["FIELD_LABEL"].ToString().Trim()+" :" ;

                            objCell1.Controls.Add(lbl);
                            objRow.Cells.Add(objCell1);
                        }
                        if (l == 2)
                        {
                            HtmlTableCell objCell2 = new HtmlTableCell();
                            objCell2.Align = "left";
                            objCell2.RowSpan = 1;
                            objCell2.ColSpan = 1;
                            objCell2.Width = "15";
                            objCell2.Height = "20";
                            objRow.Cells.Add(objCell2);
                        }
                        if (l == 3)
                        {
                            HtmlTableCell objCell3 = new HtmlTableCell();
                            objCell3.RowSpan = 1;
                            objCell3.ColSpan = 1;
                            objCell3.Width = "165";
                            objCell3.Height = "20";
                            string strControlType = objDt.Rows[k - 1]["FIELD_TYPE"].ToString().Trim();
                            if (strControlType == "D")
                            {

                                DropDownList ddltype = new DropDownList();
                                ddltype.ID = "DropDownList" + k.ToString();
                                ddltype.Style["Width"] = "165px";
                                if (ddltype.ID == "DropDownList1")
                                {
                                    ddltype.Items.Add(new ListItem("--Select one--", "-1"));
                                    ddltype.Items.Add("One");
                                    ddltype.Items.Add("Two");
                                    ddltype.Items.Add("Three");
                                }
                                else if (ddltype.ID == "DropDownList2")
                                {
                                    ddltype.Items.Add(new ListItem("--Select one--", "-1"));
                                    ddltype.Items.Add("Center");
                                    ddltype.Items.Add("Division");
                                    ddltype.Items.Add("Group");
                                   
                                }
                                else
                                {
                                    ddltype.Items.Add(new ListItem("--Select one--", "-1"));
                                    ddltype.Items.Add("Redr");
                                    ddltype.Items.Add("Blue");
                                    ddltype.Items.Add("Green");
                                }
                                
                                objCell3.Controls.Add(ddltype);
                                objRow.Cells.Add(objCell3);
                            }
                            if (strControlType == "T")
                            {

                                TextBox txt = new TextBox();
                                txt.ID = "TextBox" + k.ToString();
                                txt.Style["Width"] = "165px";
            txt.Text = "TextBox" + k.ToString();                 
                                txt.PreRender += new System.EventHandler(this.txt_PreRender);
                                objCell3.Controls.Add(txt);
                                objRow.Cells.Add(objCell3);
                            }
                        }
                        if (l == 4)
                        {
                            HtmlTableCell objCell4 = new HtmlTableCell();
                            objCell4.Align = "left";
                            objCell4.RowSpan = 1;
                            objCell4.ColSpan = 1;
                            objCell4.Width = "10";
                            objCell4.Height = "20";
                            objRow.Cells.Add(objCell4);
                        }
                        myNewTable.Rows.Add(objRow);
                        myNewTable.Visible = true;
                    }
                  
                    
            }

        }
        base.OnInit(e);
    }
//
//

//
//
Reset the dropdown to default selected value.
protected void btnReset_Click(object sender, ImageClickEventArgs e)
    {
        DropDownList ddl = new DropDownList();
        ddl = (DropDownList)this.Master.FindControl("Content").FindControl("myNewTable").FindControl("DropDownList1");
        ddl.SelectedValue = "-1";
        ddl = (DropDownList)this.Master.FindControl("Content").FindControl("myNewTable").FindControl("DropDownList2");
        ddl.SelectedValue = "-1";
        ddl = (DropDownList)this.Master.FindControl("Content").FindControl("myNewTable").FindControl("DropDownList5");
        ddl.SelectedValue = "-1";
    }
//

You must Sign In to use this message board.

FAQ    Noise Tolerance Very HighHighMediumLowVery Low   Layout Expand Posts & RepliesThread ViewNo JavascriptNo JS + Preview   Per page 102550

Msgs 1 to 3 of 3 (Total in Forum: 3) (Refresh) FirstPrevNext

Also Matthew Hazlett 10:39 2 Oct '07   Instead of: ddl = (DropDownList)this.Master.FindControl("Content").FindControl("myNewTable").FindControl("DropDownList5"); ddl.SelectedValue = "-1"; When you create a control you can add it to a hash table, like so: Hashtable myHash = new Hashtable(); myHash.Add("Label1", new Label()); myHash.Add("DropDown1", new DropDown()); Label thisLabel = myHash["Label1"] as Label; DropDownList thisDropDown = myHash["DropDown1"] as DropDownList; This way you don't have to worry about findcontrol (a very ugly function). Or because you only have 3 and not a dynamic amount you could just assign them to variables, Just a thought. Matthew Hazlett Sometimes I miss the simpler DOS days of Borland Turbo Pascal (but not very often). Sign In·View Thread·PermaLink 3.00/5 (1 vote) Re: Also Ganesan Sankaran 19:10 2 Oct '07   Yes your are correct we can also do this way. Thanks. With Regards Ganesan.S Software Engineer Sign In·View Thread·PermaLink 1.00/5 (1 vote) Very messy, try this Matthew Hazlett 10:15 2 Oct '07   private TableCell BuildCell(int height, int width, string value)       {             TableCell cell = new TableCell();             cell.Height = height;             cell.Width   = width;             cell.Text = value;             return cell;       }       private TableRow BuildRow(TableCell[] theseCells)       {             TableRow Row = new TableRow();             Row.Cells.AddRange(theseCells);             return Row;       }       private void generate()       {             Table myTable = new Table();             myTable.Controls.Add(BuildRow(new TableCell[]                      {                            BuildCell(50, 50, "This"),                            BuildCell(50, 50, "is"),                            BuildCell(50, 50, "much"),                            BuildCell(50, 50, "cleaner")                      }));             myTable.Controls.Add(BuildRow(new TableCell[]                      {                            BuildCell(50, 50, "This"),                            BuildCell(50, 50, "is"),                            BuildCell(50, 50, "untested"),                            BuildCell(50, 50, "code")                      }));             myTable.Controls.Add(BuildRow(new TableCell[]                      {                            BuildCell(50, 50, "But"),                            BuildCell(50, 50, "it"),                            BuildCell(50, 50, "should"),                            BuildCell(50, 50, "work")                      }));             Page.Controls.Add(myTable);       } Of course you will need to add a few overloads to the BuildCell to accommodate other data types / objects routine but you get the idea. Matthew Hazlett Sometimes I miss the simpler DOS days of Borland Turbo Pascal (but not very often). Sign In·View Thread·PermaLink 2.75/5 (4 votes)

Last Visit: 12:37 8 Nov '09     Last Update: 12:37 8 Nov '09 1