Go Premium for a chance to win a PS4. Enter to Win

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 774
  • Last Modified:

asp.net c# placeholder

Q1: I have a list of placeholder name (.ascx) saved in database. like
hello1.ascx
hello2.ascx
hello3.ascx

I plan to use query to get list of placeholder into frontend placeholder object in aspx.
I have no problem to query them, but i don't know how to parse to the frontend placeholder.

Can you show me how? I would like to see in a function call because I will put it into App_Code folder.

Thanks,


0
Webboy2008
Asked:
Webboy2008
1 Solution
 
BuggyCoderCommented:
please explain in detail. can't make out anything out of your question
0
 
Webboy2008Author Commented:
Table Name TblPlaceHolder

Column Name: PlaceHolder
hello1.ascx
hello2.ascx
hello3.ascx

Query Select PlaceHolder from TblPlaceHolder

Using Ado to get resultset from the query
Put all of the ascx to a single placeholder.
shown on the aspx

All languages using c#/asp.net

Hope this helps.


0
 
MLSmuddeCommented:
I am assuming the user controls are files within your website.   To add a user control to an existing placeholder you add the control to the placeholder's contols collection.

UserControl myControl = Page.LoadControl("hello1.ascx");
TblPlaceHolder.Controls.Add(myControl);

To avoid viewstate issues,  you should add the controls in the page's OnInit method.
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
carlnorrbomCommented:
Hi,

I think you are after something like this:
    protected void Page_Load(object sender, EventArgs e)
    {
        //Get all the placeholder names from the database
        SqlConnection dbConn = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\Database.mdf;Integrated Security=True;User Instance=True");
        SqlDataAdapter da = new SqlDataAdapter("SELECT PlaceHolder FROM tblPlaceHolder", dbConn);
        DataTable dtPlaceHolders = new DataTable();
        da.Fill(dtPlaceHolders);
        //Find the master placeholder in the page
        PlaceHolder phMain = (PlaceHolder)Page.FindControl("phMain");
        //Iterate over the database results to instantiate and load the user controls into the main placeholder
        foreach(DataRow row in dtPlaceHolders.Rows) {
            UserControl dbPlaceHolder = (UserControl)Page.LoadControl("~/" + row[0].ToString());
            phMain.Controls.Add(dbPlaceHolder);
        }
    }

Open in new window


Above example assumes you have a placeholder in your page with ID="phMain" and the three user controls in the root of your app.

/Carl.
0
 
Webboy2008Author Commented:
error pointing to this code: phMain.Controls.Add(dbPlaceHolder);
Error Message: System.NullReferenceException: Object reference not set to an instance of an object.
When I use response.write to see the string.
It shows correct directory path.



using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        SqlConnection DBSuretyCon = new SqlConnection(WebConfigurationManager.ConnectionStrings["SuretyDb"].ToString());
        SqlDataAdapter da = new SqlDataAdapter("SELECT AscxName FROM AdditionalInfoUI WHERE ClassCodeId =7 AND StatusId = 1",DBSuretyCon);

        DataTable dtPlaceHolders = new DataTable();
        da.Fill(dtPlaceHolders);
        //Find the master placeholder in the page
        PlaceHolder phMain = (PlaceHolder)Page.FindControl("phMain");
         //Iterate over the database results to instantiate and load the user controls into the main placeholder
        foreach (DataRow row in dtPlaceHolders.Rows)
        {
            UserControl dbPlaceHolder = (UserControl)Page.LoadControl("~/" + row[0].ToString());
            Response.Write("~/" + row[0].ToString() + "<br>");
            phMain.Controls.Add(dbPlaceHolder);

            
          }
        
    }   
}

Open in new window

0
 
carlnorrbomCommented:
Hi,

And you are sure you have the specific user control on that path? To me it sounds as if it can't find the usercontrol in question on the given path. The code works just fine for me on my end.

/Carl.
0
 
Webboy2008Author Commented:
it is a correct path
0
 
carlnorrbomCommented:
Hi,

For Your reference and a proof of concept and validation of provided code, please see:

 carlnorrbom-373377.flv
0
 
Webboy2008Author Commented:
When I comment the following line of code. it is working.
PlaceHolder phMain = (PlaceHolder)Page.FindControl("phMain");
0
 
Webboy2008Author Commented:
And I put PlaceHolder1.Controls.Add(dbPlaceHolder) instead in the ForEach Loop
0
 
carlnorrbomCommented:
Hi,

Well naturally you need to replace the phMain ID with whatever is relevant in your solution, this is just a working sample.

/Carl.
0
 
Webboy2008Author Commented:
It is working great. Thank you for your helps and efforts.

I have another post for 500pts if you want to try.

http://www.experts-exchange.com/Programming/Languages/.NET/ASP.NET/Q_26637414.html
0

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now