Tag: Sharepoint

Secure application pages in Sharepoint applications

For SharePoint applications, some times we have to create ASP.NET Application pages that reside under the _layouts folder and are not managed by SharePoint Security system.

We have to secure them manually by code, one way is to check in Page_Load and disable controls if necessary.

protected void Page_Load(object sender, EventArgs e)
        {
            if (!UserIsAuthorized)
            {
                //hide the form
                //show an error message
            }
}

Make sure to check if user is authorized in critical methods.

To check if user is authorized:

protected UserIsAuthorized
{
   get
  {
      SPUser  user = SPContext.Current.Web.CurrentUser;

     if(user==null) return false;//anonymous/public users

     //check if user belongs to authorized groups
            string[] validGroups = new string[] { “Group A”, “Group B };
            SPGroupCollection groups = user.Groups;
            foreach (SPGroup group in groups)
                if (validGroups.Contains(group.Name))
                    return true;

    //check if user is System Account
    if (user.ID == SPContext.Current.Web.Site.SystemAccount.ID)
                return true;

    return false;//user is not authorized;
   }
}

When migrating data between Sharepoint farms, use impersonation

ASP.NET impersonation allows the ASP.NET code to run as different users.

If you use only one account to migrate data between SharePoint farms, all the records will eventually be marked as modified by that account.
By using impersonation, you will be able to retain user history.

UpdatePanel in Sharepoint

Apparently UpdatePanel doesn’t work in SharePoint because reasons.

To get it to work, you have to jump through hoops by downloading the SharePoint guidance library thingy as some source code and build it yourself, then deploy it to the GAC of your environment, then add reference to Microsoft.Practice.SPG.AjaxSupport.dll, then use a SafeScriptManager in the usercontrol of your SharePoint webpart.

Maybe it’s better to build the thing using pure HTML and javascript?

Cannot get workflow to trigger event receiver

Change the sequence number of the receiver in Elements.xml to a lower value so that the receiver will run before the workflows?

Another way is to actually update the list item inside the workflow, usually assigning the same value to the field will work and results in no change to the list item.

Please note that workflow status is set asynchronously, meaning if you make the workflow trigger the event receiver and inside event receiver you read the workflow status, the workflow status is not guaranteed to be correct at the time as the update happens asynchronously.

The best way to read the eventual workflow status is to write it to a list item’s field and read from there in the event receiver.

Allow ASP.NET form to be used after downloading a file in SharePoint webpart

Solution: the most effective solution: add “_spFormOnSubmitCalled=false;_spSuppressFormOnSubmitWrapper=true;” to OnClientClick of the button

<asp:LinkButton ID=”lbExport”
runat=”server” Text=”Export”
OnClick=”lbExport_Click”
OnClientClick=”_spFormOnSubmitCalled=false;_spSuppressFormOnSubmitWrapper=true;”/>

Solution:

Add this code to the .ascx file

<script type=”text/javascript”>
    function setFormSubmitToFalse() {
        setTimeout(function () { _spFormOnSubmitCalled = false; }, 3000);
        return true;
    }
</script>

Then, for the download button, add the code to call this function after user clicks it

OnClientClick=”setFormSubmitToFalse”

Another way is to refresh the page on client after certain time

onclientclick="timedRefresh(2000)"

then in your html..

    <script type="text/JavaScript">
    <!--
    function timedRefresh(timeoutPeriod) {
        setTimeout("location.reload(true);",timeoutPeriod);
    }
    //   -->

EventReceiver cheat sheet

List item:
List BeforeProperties AfterProperties properties.ListItem
ItemAdding No value New value Null
ItemAdded No value New value New value
ItemUpdating No value Changed value Original value
ItemUpdated No value Changed value Changed value
ItemDeleting No value No value Original value
ItemDeleted No value No value Null
Document Library:
Library BeforeProperties AfterProperties properties.ListItem
ItemAdding No value No value Null
ItemAdded No value No value New value
ItemUpdating Original value Changed value Original value
ItemUpdated Original value Changed value Changed value
ItemDeleting No value No value Original value
ItemDeleted No value No value Null