Impersonation in Event Receiver

Recently faced an issue while working with Event Receivers. That is, current user need to impersonate with higher privilege account. Normally we do that with application pool account. 


Th problem here is, if you try to use event receiver's 'property' object to access the current web or the list item, the impersonation never works there. For example, following piece of code will use current user credentials, not the application pool account permission.


SPSecurity.RunWithElevatedPrivilege(delgate
{
properties.ListItem.Delete();
});


For using impersonation, you need to create a separate instances of SPWeb, then access your items.

SPSecurity.RunWithElevatedPrivilege(delgate

{

  using(SPSite site = new SPSite(properties.WebUrl))

  {

     using(SPWeb web = site.OpenWeb())

     {

         //access your items here.

     }

  }

});

Logging error message in SharePoint Programmatically

To log an error message from your custom code, first you need to take reference of 
"Microsoft.Office.Server.dll". From this dll we will use the diagnostics features.


Namespace:
Microsoft.Office.Server.Diagnostics


Next, following method need to be used for logging a message in SharePoint Log.



         private void LogULS()
        {
            PortalLog.LogString("A test Error Message.");
        }


The log can be access from 
"C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\LOGS" directory.

Creating a SandBox solution in SharePoint 2010

The Sandbox solution is newly added in SharePoint 2010, and it is very useful particularly for the Administrators to track each of the custom development object. 


Now, the administrator can monitor the performance of the custom application and that can be removed if more server resources are consumed. Another important thing is, the Sandbox solution run on a separate process thread SPUserCodes. This will stop taking SharePoint resources already using W3WP process.


For every site, there is a solution gallery, where already installed sandbox solutions are present.

Steps for creating the solution:


1) Create a blank solution in VS 2010, and specify the site URL and select "Sandbox solution"


2) Add a webpart, by click on project -> New Items
Please Note, the Visual Webpart is not supported in a Sandbox solution.


3) Write you custom codes for your webpart in the "CreateChildControl" method.


4) Build the solution and locate the WSP file in the Bin folder.


5) Now, open Power Shell and execute these commands for adding and installing the solution.


Add-SPUserSolution -LiteralPath "Physical path to WSP" -Site "Your site Url"


Install-SPUserSolution -Identity "WSP name" -Site "Your site url"

Remember: Run the Power Shell as an administrator.

Static Navigation Menu on a Site Collection

Here, I am trying to change the built-in top navigation menu with a custom made menu. These menu items are static in nature and controlled from a XML file. 


These are the steps need to be followed:


1) Create a XML file and save the file as .sitemap


< ?xml version="1.0" encoding="utf-8" ? >
< siteMap >
  < siteMapNode title="Company" url="" >
    < siteMapNode title="Profile" >
      < siteMapNode title="About Us" url="/Default.aspx" >
        < siteMapNode title="History" url="/division1/division1a/Default.aspx" >
          < siteMapNode title="Management" url="/division1/division2a/Default.aspx"/ >
        < /siteMapNode >
        < siteMapNode title="News" url="/divi/division3a/Default.aspx" >
          < siteMapNode title="Media" url="/dion1/division3a/Default.aspx"/ >
        < /siteMapNode >
      < /siteMapNode >
    < /siteMapNode >
    < siteMapNode title="Interests" >
      < siteMapNode title="Careers" url="/division1/Home.aspx" >
        < siteMapNode title="Media" url="/divisi/division1a/Default.aspx"/ >
        < siteMapNode title="News" url="/divis/division2a/Default.aspx"/ >
      < /siteMapNode >
    < /siteMapNode >
  < /siteMapNode >
< /siteMap >



2) Place the file in _app_bin directory
(eg: C:\Inetpub\wwwroot\wss\VirtualDirectories\555\_app_bin\mainmenu.sitemap)


3) Open the web.config file of the corresponding site
(eg c:\Inetpub\wwwroot\wss\VirtualDirectories\555)


4)  Look for the "< siteMap" tag, and under "< providers >" add the following entry: and save the file.


< add name="CustomXmlContentMapProvider" siteMapFile="_app_bin/CustomSiteMap.sitemap" type="Microsoft.SharePoint.Navigation.SPXmlContentMapProvider, Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" / >


5) Open the site on SharePoint Designer, and add the following inside a SharePoint:DelegateControl



     < asp:SiteMapDataSource
ShowStartingNode="true"
SiteMapProvider="CustomXmlContentMapProvider"
id="xmlSiteMap"
runat="server"/ >

6) Then look for "< SharePoint:AspMenu ID='TopNavigationMenu'
and change these:


DataSourceID="xmlSiteMap"

MaximumDynamicDisplayLevels="4" 

The MaximumDynamicDisplayLevel indicates up to how many level the menu will expand.

7) The final output will be look like this:

Page become inactive after clicking on 'Export excel' on custom SharePoint page

Recently I faced an issue on a custom page developed on SharePoint. In this page I am showing a grid and there is a button for exporting the grid data to an excel sheet. The grid also have sorting and pagination functionalities.


After deploying the page, I learnt that, after click on 'Export to excel' link the rest of the control stops functioning. This means the data sorting and pagination links are inactive. Following codes are used for exporting:



    protected void lnkExportTop_Click(object sender, EventArgs e)
    {
        try
        {
            DataTable dtProjects = (DataTable)ViewState["Projects"];
            dtProjects.DefaultView.Sort = "MPP_Name Desc";
            gvMerge.DataSource = dtProjects.DefaultView;
            gvMerge.AllowPaging = false;
            gvMerge.DataBind();


            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.AddHeader(
                "content-disposition", "attachment; filename=ProjectDashboard.xls" );
            HttpContext.Current.Response.ContentType = "application/ms-excel";

            using (StringWriter sw = new StringWriter())
            {
                using (HtmlTextWriter htw = new HtmlTextWriter(sw))
                {
                    //  Create a table to contain the grid
                    Table table = new Table();

                    //  include the gridline settings
                    table.GridLines = GridLines.Both;

                    //  add the header row to the table
                    if (gvMerge.HeaderRow != null)
                    {
                        PrepareControlForExport(gvMerge.HeaderRow);
                        table.Rows.Add(gvMerge.HeaderRow);
                    }

                    //  add each of the data rows to the table
                    foreach (GridViewRow row in gvMerge.Rows)
                    {
                        table.Rows.Add(row);
                    }

                    //  render the table into the htmlwriter
                    table.RenderControl(htw);

                    //  render the htmlwriter into the response
                    HttpContext.Current.Response.Write(sw.ToString());
                    HttpContext.Current.Response.End();
                }
            }
        }
        catch (Exception ex)
        {
            HandleError("Export to excel ", ex.ToString());
        }
    }

    private void PrepareControlForExport(Control control)
    {
        for (int i = 0; i < control.Controls.Count; i++)
        {
            Control current = control.Controls[i];
            if (current is LinkButton)
            {
                control.Controls.Remove(current);
                control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text));
            }
            else if (current is ImageButton)
            {
                control.Controls.Remove(current);
                control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText));
            }
            else if (current is HyperLink)
            {
                control.Controls.Remove(current);
                control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text));
            }
            else if (current is Image)
            {
                control.Controls.Remove(current);
            }
          
            if (current.HasControls())
            {
                PrepareControlForExport(current);
            }
        }
    }




Initially I thought that there is some problems with my code. But after several debugging cycle I concluded that my code is working fine.


After some researching on the net, I found that SharePoint security model basically causing the problem. Some client scripts need to call on the OnClilentClick method of the export link button.



< asp:LinkButton ID="lnkExportBottom" runat="server" Text="Export to excel" OnClientClick="_spFormOnSubmitCalled = false;_spSuppressFormOnSubmitWrapper=true;"
OnClick="lnkExportTop_Click"  / >

Hiding left blank space of Application.master in SharePoint

While developing on SharePoint once I required to use the built-in Application.master page. This master page is attached to my custom aspx page. After deployed the aspx page I noticed that, there is some blank space on the left portion of the page.

I used the following scripts to hide the left unused space and finally the page is able to use more screen space.

    < script language="javascript" type="text/javascript" >

        document.getElementById('LeftNavigationAreaCell').style.display = 'none';

        document.getElementById('TitleAreaImageCell').style.display = 'none';

        document.getElementById('onetidMainBodyPadding').style.display = 'none';

    < /script >

After adding this script the finally looks like this:

Matching lookup column values using CAML query

To fetch items from a list based on a lookup column value, I tried the following query first.


< Query >
  < Where >
    < Eq >
        < FieldRef Name="Roadmap_x0020_Address" / >
        < Value Type="Lookup" > xyz < /Value >
   < /Eq >
 < /Where >
< /Query >


But, have not got the desired result because this query matches on the title of a lookup column, there there are cases where we can have a duplicate title. As we know that the lookup value structure is 12;#xyz, Instead of fetching by name we should look by ID


To fetch information by ID, we need use this switch LookupId=”TRUE”

< Query >

  < Where >
    < Eq >
        < FieldRef Name="Roadmap_x0020_Address" LookupId=”TRUE” / >
        < Value Type="Lookup" >12 < /Value >
   < /Eq >
 < /Where >
< /Query >

Another thing to remember is, the "FieldRef Name" we are using should be the internal name of a SharePoint column.