ASP.NET - Image reading from cache!

[Tea Maker]

Hello experts,

I have an Ajax UpdatePanel inside my page. When I click on the "Change Image" button inside it, the image in that panel will change dynamically, based on an external XML file, that I created to manage the images to display.

Note that most of the time the image change, but sometimes, when I click the button, the image doens't change, and I have to click once more, or sometimes twice, for the image to change.

Do you think guys this is happening because only the ajax area is refreshing and not the whole page? How can I solve this problem? Is there any way to avoid an image to read from the cache, even if it's inside an Ajax UpdatePanel?

Please advice...

Best regards,
Wassim

[shweta123]

Hi,

I think the you are getting refresh problem of the image because you have taken the Button inside the update panel.Only image should be inside the panel.
e.g.

<asp:Button ID="Button1" 
                Text="Refresh Panel"
                runat="server" />
    <asp:ScriptManager ID="ScriptManager1" 
                       runat="server" />
    <asp:UpdatePanel ID="UpdatePanel1" 
                     UpdateMode="Conditional"
                     runat="server">
                     <Triggers>
                       <asp:AsyncPostBackTrigger ControlID="Button1" />
                     </Triggers>
                     <ContentTemplate>
                     <img id="Image1" src=".."/>
                      </ContentTemplate>
    </asp:UpdatePanel>
 

Hello experts,

I have an Ajax UpdatePanel inside my page. When I click on the "Change Image" button inside it, the image in that panel will change dynamically, based on an external XML file, that I created to manage the images to display.

Note that most of the time the image change, but sometimes, when I click the button, the image doens't change, and I have to click once more, or sometimes twice, for the image to change.

Do you think guys this is happening because only the ajax area is refreshing and not the whole page? How can I solve this problem? Is there any way to avoid an image to read from the cache, even if it's inside an Ajax UpdatePanel?

Please advice...

Best regards,
Wassim

[Frinavale]

Hello experts,

I have an Ajax UpdatePanel inside my page. When I click on the "Change Image" button inside it, the image in that panel will change dynamically, based on an external XML file, that I created to manage the images to display.

Note that most of the time the image change, but sometimes, when I click the button, the image doens't change, and I have to click once more, or sometimes twice, for the image to change.

Do you think guys this is happening because only the ajax area is refreshing and not the whole page? How can I solve this problem? Is there any way to avoid an image to read from the cache, even if it's inside an Ajax UpdatePanel?

Please advice...

Best regards,
Wassim

By any chance, do you have some images with the same name that are being displayed with different content?
Sometimes the pictures are cached by the web browser and if they have the same name, wont re-download the newer picture.

Could you please post your asp code for the update panel :)

-Frinny

[Tea Maker]

Thank you guys for your replies so far.

shweta123: Thank you my friend, at the beginning i placed a Trigger, and I had the same problem, and besides this, the w3c did not validate the page because of the trigger itself, so I took the button inside the UpdatePanel, and remove the trigger part and page was validated with no errors. But I assure to you the problem occured even when the button was outside the panel and handle it using the trigger.

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Image ID="Image1" runat="server" BorderWidth="1px" BorderColor="#192742" BorderStyle="Dashed" Width="170" Height="90" AlternateText=" " />
<br />
<asp:Label ID="lblProject2" runat="server" Text="Label" ForeColor="#192742" Width="128px"></asp:Label>
<br />
<asp:Button ID="Button1" runat="server" Text="Scramble" Width="146px" />
</ContentTemplate>                      
</asp:UpdatePanel>

FYI: The ScriptManager is put at the top of the page.

Note that I am handling the source of the image through the code behind page. The images are displayed randomly through a list of 50 images. *Most* of the time, the images change, only few times I have to click twice.
And I don't think it's a luck that the random number retrieve the same number, because I actually have *TWO* images, and when this problem occur, the same two images stay at the same place, and the probability for this to happen is almost null, you already know...

Let's hope I gave you sufficient informations, and I appreciate your time helping me in this issue.
If you want guys I can send you a link to my page online to your email, but I can't put it here due to personal reasons, and for respecting the forum's rules as well.

Best regards,
Wassim

[Tea Maker]

By any chance, do you have some images with the same name that are being displayed with different content?
Sometimes the pictures are cached by the web browser and if they have the same name, wont re-download the newer picture.

Could you please post your asp code for the update panel :)

-Frinny

Hello Frinny,

I have answered your questions above, but I thought I don't have to push the reply button under your reply, in order for the email to be sent to you. Please let me know if what I said above make any sense to you.

Best regards,
Wassim

[shweta123]

Hi,

If you are generating the images at the backend , please check that the image is present on the hard disk before displaying by debugging it.
It is also possible that image is created but it is blank so you can not see it.