ASP.NET

11-Jun-09 15:37

Ok so I have a database of images, a certain amount of which i want to display on a webpage at a time.
The way it is working at the moment is each time the "next" button is clicked, it uses Response.Redirect() and supplies a query string to select the next 6 images to display them. This works ok but each time the whole page has to load so I would prefer if i could use an updatepanel.
I have tried this and instead of supplying a query string the button click event increments the number of selection of images to be displayed.
However, when the updatepanel updates the previous number is lost and does not increment because it is set back at 0.
Is there any other way to do this without loading the whole page each time.
Sorry if I've explained it badly...
if you need more info I can post the code...
thanks Smile | :)

N a v a n e e t h11-Jun-09 15:47

11-Jun-09 15:47

How are you tracking the previous number?

Navaneeth

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toprogramminguy11-Jun-09 16:10

11-Jun-09 16:10

If I understand which number you are talking about (the one for the update panel?) I just had it as an int which was set on the page_load event. Then when the button was clicked it incremented the number by 6 and called the getImage function which gets the images form the database. But when the updatepanel is updated it resets the int back to the original number so it just loops...
but what i cant understand is that it increments once but thats it Confused | :confused:

It's probably something dumb but I cant figure it out. Roll eyes | :rolleyes:

like this anyway:

public partial class comicBrowser : System.Web.UI.UserControl
{
    public int currentComics;
    private Panel thumbnails = new Panel();
    private string connectionString;
    protected void Page_Load(object sender, EventArgs e)
    {
        currentComics = 6;
        setConnectionString();
        UpdatePanel1.ContentTemplateContainer.Controls.Add(thumbnails);
        accessDatatables();
    }

    private void setConnectionString()//gets the connection string from the .comfig file
    {
        Configuration Config =
                System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("/WebSite");
        ConnectionStringSettings connString;
        if (0 < Config.ConnectionStrings.ConnectionStrings.Count)
        {
            connString =
                Config.ConnectionStrings.ConnectionStrings["data"];
            if (null != connString)
                connectionString = connString.ConnectionString;
        }
    }

    private void accessDatatables()
    {
        SqlConnection conn = new SqlConnection(connectionString);

        SqlDataReader readr = null;

        SqlCommand cmd = null;

        try
        {
            conn.Open();
            cmd = new SqlCommand("SELECT comicUrl, comicId, comicRating, comicName FROM comicDatabase WHERE (comicId <= " + currentComics +
                ") AND (comicId > " + (currentComics - 6) + ")", conn);

            readr = cmd.ExecuteReader();

            while (readr.Read())
            {
                loadMenu(readr.GetString(0), readr.GetInt32(1), readr.GetInt32(2), readr.GetString(3));
            }
        }
        catch(Exception ex)
        {
            this.Page.Title = ex.ToString();
        }
        finally
        {
            if (conn != null)
                conn.Close();

            if (readr != null)
                readr.Dispose();
        }
    }

    private void loadMenu(string comicUrl, int comicId, int comicRating, string comicName)...

    protected void right_Click(object sender, ImageClickEventArgs e)
    {
        currentComics += 6;

        thumbnails.Controls.Clear();//clears previous images

        accessDatatables();//gets and displays the images

        updatejavascript();
    }

    protected void left_Click(object sender, ImageClickEventArgs e)
    {
        currentComics -= 6;

        thumbnails.Controls.Clear();//clears previous images

        accessDatatables();//gets and displays the images

        updatejavascript();
    }
    private void updatejavascript()
    {
        ScriptManager.RegisterStartupScript(UpdatePanel1, typeof(UpdatePanel), "scriptkey", "updateJavascript();", true);
        //calls a javascript function to reload animations for the elements
    }
}

sorry about plonking a heap of it in...

N a v a n e e t h11-Jun-09 16:21

11-Jun-09 16:21

toprogramminguy wrote:
protected void Page_Load(object sender, EventArgs e)
{
currentComics = 6;
setConnectionString();
UpdatePanel1.ContentTemplateContainer.Controls.Add(thumbnails);
accessDatatables();
}

There is the problem. Update panel doesn't refresh the page, but it does a postback and your page load will execute all the time. So guard the page load code with !IsPostBack check. Also the currentComics variable is a class level variable and it's value will be reset each time. So you need to persist the value may be using viewstate or other persisting mechanisms.

Smile | :)

Navaneeth

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toprogramminguy11-Jun-09 16:42

11-Jun-09 16:42

Ok now I've added this:

protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            currentComics = 6;
            setConnectionString();
            UpdatePanel1.ContentTemplateContainer.Controls.Add(thumbnails);
            accessDatatables();
        }
        else currentComics = (int)ViewState["currentcomics"];
    }

and this:

protected void right_Click(object sender, ImageClickEventArgs e)
    {
        currentComics += 6;

        ViewState["currentcomics"] = currentComics;

        thumbnails.Controls.Clear();//clears previous images

        accessDatatables();//gets and displays the images

        updatejavascript();
    }

but when it gets to here(in the first code block):

else currentComics = (int)ViewState["currentcomics"];

then it says: Object reference not set to an instance of an object.
Am i using the viewstate wrong?

N a v a n e e t h11-Jun-09 17:11

11-Jun-09 17:11

toprogramminguy wrote:
Am i using the viewstate wrong?

page_load executes first before executing the button click handler. So first time ViewState["currentcomics"] will have NULL value. So do a NULL check before you access the value. Something like..

else currentComics = ViewState["currentcomics"] == null ? 6 : (int)ViewState["currentcomics"];

Smile | :)

Navaneeth

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toprogramminguy11-Jun-09 17:21

11-Jun-09 17:21

Ya i have done that now, but it wasnt on the first run that the exception was thrown because it wouldnt have been a postback, it was when I clicked the next button which has me all confused again Roll eyes | :rolleyes:

does the accessDatatables(); get called when i call it in the buttonclick event handler or when the updatepanel is reloaded?

N a v a n e e t h11-Jun-09 17:31

11-Jun-09 17:31

toprogramminguy wrote:
but it wasnt on the first run that the exception was thrown

Yes. It will be thrown when you clock the next button for the first time. Your else portion will get executed, but since ViewState is not created for the key you are accessing, it will return NULL.

toprogramminguy wrote:
does the accessDatatables(); get called when i call it in the buttonclick event handler or when the updatepanel is reloaded?

I am not getting what you mean here. It will be called when the next button is clicked.

Navaneeth

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toprogramminguy11-Jun-09 17:41

Textbox Focus with ajax timer

11-Jun-09 17:41

Ok. Now the button is incrementing the currentcomic value but when the updatecontrol reloads nothing is displayed event though the updateprogress is showing so I know something is happening.

Thanks for your help.
I'll figure out the rest of it myself...hopefully Unsure | :~

Help to Test a web app

AlexeiXX311-Jun-09 14:56

AlexeiXX3

11-Jun-09 14:56

Hi, thanks for looking, i had posted this link in the testing forum, but that forum is kind of "lonely"

I made a web app: PideEnLinea.com[^]

Im not sure how secure it is, i did follow some security guidelines, but who knows
Also i made some load tests

If someone has a chance, please visit it and try to make some sql injections, XSS or try to hack it
If you do hack it or make sql injections or XSS, please let me know by replying here :P

Thanks in advance for any feedback

Alexei Rodriguez

Mohammed Elkholy11-Jun-09 8:44

Mohammed Elkholy

11-Jun-09 8:44

Dear all

i have a page included ajax timer

and textbxo while i focus and write in textbox i lose the focue when the time ticke work

and i should set the textbox focus to continue writting and i lose it again when the timer work

i need help for this i want finish writting in textbox while the timer working

thanks for help

MD_NADA

Christian Graus11-Jun-09 14:14

Christian Graus

11-Jun-09 14:14

Hard to comment without seeing code, but I would suspect that you perhaps want to reset your timer while the textbox has focus ? What does the timer do ? It sounds like it moves the focus to some other control.

Christian Graus

Driven to the arms of OSX by Vista.

"! i don't exactly like or do programming and it only gives me a headache." - spotted in VB forums.

I can do things with my brain that I can't even google. I can flex the front part of my brain instantly anytime I want. It can be exhausting and it even causes me vision problems for some reason. - CaptainSeeSharp

Mohammed Elkholy11-Jun-09 17:09

Mohammed Elkholy

11-Jun-09 17:09

i am sorry i didn't descrip my case well

but my homepage has many usercontrol

some of these controls included ajax timer and in my home page i have 1 control for search and one control
for login

if i write in search textbox it is easy until the timer ticker work

i lose the focus of textbox and i cant continue write in textbox and the samler to login textbox

i hope i descrip it well

MD_NADA

N a v a n e e t h11-Jun-09 17:14

11-Jun-09 17:14

Still you haven't answered the question - What does timer do? Is it setting focus to some other control?

Navaneeth

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