Arjuna: July 2010

Saturday, July 31, 2010

Error Accessing Path

Today is a day full of errors, when I fixed one error another error came while trying to run my hosted application. This time it was “Access to the path 'C:\inetpub\wwwroot\……’ is denied.

Full error is as follows,

Access to the path 'C:\inetpub\wwwroot\Mining2 Setup\Images\temp\tempImage.png' is denied.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.UnauthorizedAccessException: Access to the path 'C:\inetpub\wwwroot\Mining2 Setup\Images\temp\tempImage.png' is denied.

The issue here was generated by a code written in my application which tries to access an image named tempImage.png in the said folder (Images\temp).

The reason for this is when you install IIS 7 the account used by the application pool (IIS_IUSRS) is not given access to the folder Images\temp. Since it is created by the application I just installed.

To sort out the issue give write permission to the folder Images\temp for the account IIS_IUSRS using the security tab in the folder properties page.

Friday, July 30, 2010

Error when Installing MSI

Recently when trying to install a setup I made for a project on a new server having Windows Server 2008 R2 I continuously encountered an error as of below.

“The installer was interrupted before “Application” could be installed. You need to restart the installer to try again.”

image_thumb[2]

The server had IIS 7, .Net Framework 3.5 and 4 installed. After putting in some time onto this I found out that this is because the II6 Management Compatibility services was not installed for the Web Server role.

To fix it simply open the Server Manager and open up Web Server role and click on Add Role Services.

Then select IIS 6 Management Compatibility node and all the child nodes below in under the Management Tools parent node and press next.

When the installation is complete the setup will work as desired.

image_thumb[4]

Friday, July 23, 2010

Changing the Control Style at Runtime using the ASPX

Recently I changed the style of some controls in my ASPX page at runtime based on the values set on another control in my page. For example the color of the table is changed based on the radio button that was selected and the color of the button is changed according to the text that was typed in the textbox. Hope this is helpful.

       
       
        
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Changing the Control Style</title>
     <style type="text/css">
        .Style1
        {
            background-color: Red;
        }
        .Style2
        {
            background-color: Blue;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <asp:RadioButton ID="RadioButton1" runat="server" Text="Red" GroupName="1" Checked="True" AutoPostBack="True" />
        <asp:RadioButton ID="RadioButton2" runat="server" Text="Blue" GroupName="1" AutoPostBack="True" />
        <!-- Styling the table based on the radio button selection. -->
        <table class="<% if(RadioButton1.Checked) { %> Style1 <% } else { %> Style2 <% } %>">
            <tr>
                <td> &nbsp; See the change... </td>
            </tr>
            <tr>
                <td> &nbsp; </td>
            </tr>
        </table>
        <asp:TextBox ID="TextBox1" runat="server" MaxLength="3"></asp:TextBox>
        <!-- Styling the button based on the textbox value. -->
        <input id="Button1" type="submit" value="button" 
               class="<% if(TextBox1.Text=="") { %> Style1 <% } else { %> Style2 <% } %>" />
    </form>
</body>
</html>
           
        
       

Output looks as below.

Tuesday, July 20, 2010

Cure for HIV/AIDS

Even though very little publicity was given a great medical finding was done by an American Doctor working in Berlin to find a cure for HIV/AIDS or Human Immunodeficiency Virus / Acquired Immune Deficiency Syndrome.

As per the articles a stem cell transplant from a donor who had a gene mutation known as “CCR-5 Delta- 32” cured a patient with HIV infection with no traces of HIV after two years of the transplant.

At the moment a transplant is much riskier thing to do since it involves of destroying and rebuilding the patients’ immune system. But this case of success will open up new ways to think and will help finding more safe and solid cures for HIV/AIDS in the near future.

Thursday, July 15, 2010

Firing TreeView TreeNodeCheckChanged Event

Normally in ASP.Net TreeView you can enable it to show checkboxes in its node levels. So if you need to do any actions when a node is checked or unchecked you need to use the TreeNodeCheckChanged event. But the problem is TreeNodeCheckChanged event will not fire when a checkbox is clicked. The cause for this is because the TreeNode class which represents a node in the TreeView will not add onClick event on the checkbox.

But if you carefully check it the event is getting fired at the next page postback. Since I needed to do some actions when the checkbox statuses are changed I made the page post back when a checkbox is checked or unchecked by the following java script. What it does is simply it will check the element which caused the event is a checkbox and do a postback of the page.

<script type="text/javascript">
     function TreeViewCheckBoxClicked(Check_Event) {
         var objElement;
         try {
             // Get the element which fired the event.
             objElement = window.event.srcElement;
         }
         catch (Error) {
             //srcElement is failing, objElement is null.
         }
 
         if (objElement != null) {
             // If the element is a checkbox do postback.
             if (objElement.tagName == "INPUT" && objElement.type == "checkbox") {
                 __doPostBack("", "");
             }
         }
         else {
             //    If the srcElement is failing due to browser incompatibility determine 
             // whether the element is and HTML input element and do postback.
             if (Check_Event != null) {
                 if (Check_Event.target.toString() == "[object HTMLInputElement]") {
                     __doPostBack("", "");
                 }
             }
         }
     }
 </script>
 

To make this work you need to bind the onClick event with the javascript shown above as shown below.

protected void Page_Load(object sender, EventArgs e)
 {
     // Adding the onClick script to the TreeView.
     TreeView1.Attributes.Add("onClick", "TreeViewCheckBoxClicked(event)");
 }
 

Even though I have done this in Page Load this can be done in other places of code as well, for example if you are adding the TreeView by code you can use this right before adding it to the page.

The above will make the page post back when ever a checkbox in the TreeView is clicked, but nothing special will happen. You need to implement the code for TreeNodeCheckChanged event to get some task done out of it, for example I am using the following code to check or uncheck the child nodes depending on the action done for the parent node.

protected void TreeView1_TreeNodeCheckChanged(object sender, TreeNodeEventArgs e)
 {
     // Loop through all the child nodes and change the checked status as required.
     foreach (TreeNode tn in e.Node.ChildNodes)
     {
         if (e.Node.Checked)
             tn.Checked = true;
         else
             tn.Checked = false;
     }
 }
 

Tuesday, July 13, 2010

Changing GridView Column Headers

If you are wondering a way to change the column header appearing in the .Net GridView control in run time then this post will help you to get it done.

For example think that you need to change the normal grid headers shown in Screen A into something like shown in Screen B.

Screen A

Screen B

I have removed few columns from the grid header and then I did add few customized column headers. The added “Edit” column and “Id” column are spanning to 2 rows, the “Temp Columns” column is spanning to 2 columns.

I think the code is self explanatory. This way you will be able to create complex gridview headers.

       
       
        
protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
 {
     if (e.Row.RowType == DataControlRowType.Header)
     {
         // Remving the first two colummn headers.
         e.Row.Cells.RemoveAt(0);
         e.Row.Cells.RemoveAt(0);
         // Creating the gridview row object.
         GridViewRow headerGridRow = new GridViewRow(0, 0, DataControlRowType.Header, DataControlRowState.Selected);
         headerGridRow.ID = "hdrGridRow";
         TableCell HeaderCell;
         // Creating and adding the first header cell.
         HeaderCell = new TableCell();
         HeaderCell.Text = "Edit";
         HeaderCell.ID = "cellEdit";
         HeaderCell.Font.Bold = false;
         HeaderCell.HorizontalAlign = HorizontalAlign.Center;
         HeaderCell.RowSpan = 2; // Spans across 2 rows.
         HeaderCell.ColumnSpan = 1;
         HeaderCell.BackColor = System.Drawing.Color.LightGray;
         HeaderCell.BorderColor = System.Drawing.Color.White;
         HeaderCell.ForeColor = System.Drawing.Color.Red;
         headerGridRow.Cells.Add(HeaderCell);
         // Creating and adding the second header cell.
         HeaderCell = new TableCell();
         HeaderCell.Text = "Id";
         HeaderCell.ID = "cellId";
         HeaderCell.Font.Bold = false;
         HeaderCell.HorizontalAlign = HorizontalAlign.Center;
         HeaderCell.RowSpan = 2;
         HeaderCell.ColumnSpan = 1;
         HeaderCell.BackColor = System.Drawing.Color.LightGray;
         HeaderCell.BorderColor = System.Drawing.Color.White;
         HeaderCell.ForeColor = System.Drawing.Color.Red;
         headerGridRow.Cells.Add(HeaderCell);
         // Creating and adding the third header cell.
         HeaderCell = new TableCell();
         HeaderCell.Text = "Temp Columns";
         HeaderCell.ID = "cellTempColumns";
         HeaderCell.Font.Bold = false;
         HeaderCell.HorizontalAlign = HorizontalAlign.Center;
         HeaderCell.RowSpan = 1;
         HeaderCell.ColumnSpan = 2; // Spans across 2 columns.
         HeaderCell.BackColor = System.Drawing.Color.LightGray;
         HeaderCell.BorderColor = System.Drawing.Color.White;
         HeaderCell.ForeColor = System.Drawing.Color.Red;
         headerGridRow.Cells.Add(HeaderCell);
         // Adding the header row to the gridview.
         GridView1.Controls[0].Controls.AddAt(0, headerGridRow);
     }
 }
           
        
       

Arjuna