Checking to see if a list exists in SharePoint 2010

The most common way to do this is by using a try/catch block when you try to use the indexer on SPListCollection. Well, I am pleased to tell you about a new method I discovered on SPListCollection that really made my day. The new TryGetList method takes the name of a list and will get this, return a null if the list doesn’t exist. Take a look at this code.

using (SPSite siteCollection = new SPSite("http://moss-server"))
{
SPList myCustomList = siteCollection.RootWeb.Lists.TryGetList("MyCustomList");
// doesn't throw exception!
if (myCustomList != null)
{
// do something

}
}

Quick overview of Master Pages in SharePoint 2010

The first master page we will talk about is v4.master. This is the default team site master page used with version 4 of the UI. This will be the master page you typically use. It provides the ribbon bar and all of the other new visual UI changes such as the site actions menu on the left side.

If you did an upgrade to SharePoint 2010 and haven’t transitioned to the new UI yet, the old master page is still in default.master. This looks just like the master page you use in SharePoint v3 today. It doesn’t have the ribbon bar and the site actions menu is still on the right side.

The search pages by default now use minimal.master. This is a really slimmed down master page with next to nothing on it. It doesn’t even have navigation. I’m not sure why they opted to use this page in Search Center, but I think it provides an issue with people trying to leave the search center. The Office Web Applications also use this master page but that makes a little more sense because it provides more screen real estate.

The last page I will mention is simple.master. This page is used for login and error pages. From what I understand, it can’t be customized (I have no idea why), but it can be replaced.


Thanks
Sanjay Tiwari
www.YashiTech.com

Create a SharePoint list Dynamically using list template

Somebody sent me question asking how to create a sharepoint list using list template ?
Here is the sample code I have written, its working, if you have any doubt you can send me an email @ s_tiwari05@yahoo.com

Before running this code you have to have a list template created and stored into list template gallery, I am reading it from there and creating one instance of that and using it to create actual link. If you have many sites in he site collection where you want to create list you can put this code into loop and create list in each site.

web1.AllowUnsafeUpdates = true;
//Create Risk-Issue-Chnage List
txtStatus.Text = "";
lblwsname.Text = web1.Url;
SPListTemplate splt;
//Create site
SPSite site=new SPSite();
//Create web
SPWeb web=site.OpenWeb();
SPListTemplateCollection spltc;
try
{
//Retrieve all the list templates from template gallery
spltc = site.GetCustomListTemplates(web);
//Retrieve specific template you are looking for.
splt = spltc["MyListName"];

splColl = web1.Lists;
gd = splColl.Add("MyListName", "MyListTitle", splt);
splColl[gd].Update();


}
catch (Exception ex)
{
SW = File.AppendText("C:\\DeploymentLog.txt");
SW.WriteLine(" Error Occurred while creating list : " + web1.Url + " : " + ex.Message + " " + DateTime.Now.ToString() + " " + ex.StackTrace);
SW.WriteLine("--------------------------------------------------");
SW.Close();
txtStatus.Text = txtStatus.Text + Environment.NewLine + " Error Occurred while creating list, see log for detail......";
}

Sanjay Tiwari
Yashi Technologies LLC
Dallas, Texas

Creating a SharePoint List programmatically using the object model

Creating a SharePoint List programmatically using the object model

There are two ways to create a SharePoint list programmatically

1. Creating a List programmatically by using out of the box List Template Types, there are many OOTB list templates are available in the SharePoint, list of some of them is geven below.
You can create a list by picking one of the List Template Types available in the SPListTemplateType object

SPSite site = SPContext.Current.Site;
SPWeb web = site.RootWeb;
web.AllowUnsafeUpdates = true;
Guid listId = web.Lists.Add("Test Custom List", "The new custom list", SPListTemplateType.GenericList);
SPList list = web.Lists[listId];
web.AllowUnsafeUpdates = false;
site.Dispose();
web.Dispose();

OOTB List Templates


Events
Contacts
Tasks
PictureLibrary
DiscussionBoard
Survey
DocumentLibrary
Links
Document Library
Announcements
GenericList
WorkflowHistory
DataConnectionLibrary
DataSources
GanttTasks
CustomGrid
NoCodeWorkflows
XMLForm
WebPageLibrary
WorkflowProcess
Form Library
wiki
Wiki Page Library
Picture Library
Picture
Contacts
Calendar
Discussion Board
Project Tasks
Issue Tracking
Custom List
Custom List in Datasheet View
Survey Survey
Custom Workflow Process
Languages and Translators
Translation Management Library
DataSources
Data Connection Library
Workflow History
No Code Workflows




2. Creating a List programmatically with Custom List Template Types
If you have created your own custom list template, you will need to reference the id by enumerating what List Template Types are available at the Site Collection.


SPSite site = SPContext.Current.Site;
SPWeb web = site.RootWeb;
web.AllowUnsafeUpdates = true;

SPListTemplateCollection listTemplates = site.GetCustomListTemplates(mySite);
SPListTemplate template = listTemplates["Enter template name here"];
Guid listId = web.Lists.Add("Test Custom List", "The new custom list", template);
SPList list = web.Lists[listId];

web.AllowUnsafeUpdates = false;
site.Dispose();
web.Dispose();


There are some otherways also like using Feature etc to create a sharepoint list, which I am going to explain it in my next post.

Thanks
Sanjay Tiwari
Dallas, Texas

How to use elevated priviledge in Sharepoint/how to Impersonate a user in the code.

There are actually many ways to acieve that, I am going to explain two of them here.


1. Using RunWithElevatedPrivileges of SPSecurity class.

The SPSecurity class provides a method (RunWithElevatedPrivileges) that allows you to run a subset of code in the context of an account with higher privileges than the current user.

The premise is that you wrap the RunWithElevatedPrivileges method around your code. And also In certain circumstances, such as when working with Web forms, you may also need to set the AllowSafeUpdates method to true to temporarily turn off security validation within your code. If you use this technique, it is imperative that you set the AllowSafeUpdates method back to false to avoid any potential security risks.



//Using RunWithElevatedPrivileges. code written in this section will run with higher priviledges
SPSecurity.RunWithElevatedPrivileges(delegate()
{
using (SPSite site = SPContext.Current.Site)
{
using (SPWeb web = site.OpenWeb(myWeb.ID))
{
web.AllowUnsafeUpdates = true;
//Write the code here to do the operation.
web.AllowUnsafeUpdates = false;

}
}
}

Another way to use this method is , define a public method that acts simply as a front end to the method that does the "real" work.

public void ProcessMethod()
{
SPSecurity.CodeToRunElevated elevatedMethod = new SPSecurity.CodeToRunElevated( ProcessMethodAsElevated);
SPSecurity.RunWithElevatedPrivileges(elevatedMethod);
}

The code uses a method from SPSecurity to indicate the name of the method that will run with Full Control(Basically using Application Pool Account).
In the first line, simply pass in the name of the method as the parameter. In the second line, you execute that method with elevated privileges.

Now create the method that does the real work. It is called by the first method (delegate), but executes with Full Control(under Application Pool Account):
private void ProcessMethodAsElevated()
{

//code goes here to do our work

}


2. Using windows impersonation.

Using this you want to run some code under the context of another user, you will need to hook into advapi32.dll library. following libraries are to be included

using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Security.Permissions;


Then you need to declare an external reference at class level.

[DllImport("advapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
static public extern bool LogonUser(string userName, string domain, string password, int logonType, int logonProvider, ref IntPtr accessToken);


using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Security.Permissions;
using System.Data.SqlClient;

class TestClass
{

private const int LOGON_TYPE_INTERACTIVE = 2;
private const int LOGON_TYPE_PROVIDER_DEFAULT = 0;

[DllImport("advapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
static public extern bool LogonUser(string userName, string domain, string password, int logonType, int logonProvider, ref IntPtr accessToken);
static void ImpersonationCode()
{
IntPtr accessToken = IntPtr.Zero;
if (LogonUser("userName", "domain", "password", LOGON_TYPE_INTERACTIVE, LOGON_TYPE_PROVIDER_DEFAULT, ref accessToken))
{
using (WindowsIdentity identity = new WindowsIdentity(accessToken))
{
using (WindowsImpersonationContext context = identity.Impersonate())
{
// ... Write your code to implement logic here
context.Undo();
}
}
}

}

Now there is very important point, if you are doing any operation like adding a new item into library, it will leave the signature of system account and not the logged in current user. Now you may want to run the code in elevated priviledge but want to keep signature of current logged in user....coming in my next post.

Sanjay Tiwari
Dallas, Texas

How to get the latest version lable of a file

Some time it is required just to know the what was the last version of the file saved in the version enabled document library.



public Double getLastVersion(string flname, bool tt)
{
string doclibname = ConfigurationManager.AppSettings["doclibname"].ToString();
Double ver = 0;
//get the latest version
using (SPSite objSite = SPContext.Current.Site)
{
using (SPWeb objWeb = objSite.OpenWeb())
{
SPFolder mylibrary = objWeb.Folders[doclibname];
foreach (SPFile file in mylibrary.Files)
{
if (file.Name.ToString() == flname+ ".doc")
{
ver = System.Convert.ToDouble(file.UIVersionLabel);
Break;
}
}
return ver;

}
}
}


Thanks
Sanjay Tiwari
Dallas, Texas

How to delete a file from SharePoint document library.

To delete a file and all its versions from a document library where you know only the file name and not the item id etc, there is no other way but to loop through the file collection returned by "Library.File" and break the loop once you find and delete the file.

Here is the example



public void DeleteFile(string FinalFileName)
{
string s_FileName = "";
//Get the library name from webconfig file
string doclibname = ConfigurationManager.AppSettings["doclibname"].ToString();
//Get site object
SPSite objSite = SPContext.Current.Site;
SPWeb objWeb = objSite.OpenWeb();
//Get the library
SPFolder mylibrary = objWeb.Folders[doclibname];
foreach (SPFile file in mylibrary.Files)
{
if (file.Name.ToString().ToUpper() == FinalFileName.ToUpper())
{
//delete the file and exit the loop
objWeb.AllowUnsafeUpdates = true;
file.Delete();
mylibrary.Update();
objWeb.AllowUnsafeUpdates = false;
break;

}
}

}


Thanks
Sanjay Tiwari
Dallas, Texas

Uploading a document into SharePoint Document Library Part 2

Yes, this is part 2. Uploading a document in a sharepoint document library where the settings for the document libary are

1. Create a version each time you edit a file in this document library? Yes (Create major or minor versions )
2. Require documents to be checked out before they can be edited? Yes

And after uploding the document

1. You want to update a metadata column also for same document.
2. Check the document back in.

Here in this process followings are the main steps

Step 1: Get the file in binary format to be uploaded.
Step 2: Check if the file already exists in the library.
Step 3: Check if file is already checked out by somebody else.
Step 4: If file exists and not checked out by anybody else then check it out. (You wont be able to upload a file if it is not checked out).
Step 5: Upload the file.
Step 6: Check-in the file.



protected void HandleUploadDocument(object sender, EventArgs eventArgs)
{
try
{



bool flgPublish = true;

if (attachdoc.PostedFile != null)
{
if (attachdoc.PostedFile.ContentLength > 0)
{

string filename = attachdoc.PostedFile.FileName.ToString();
string[] split = filename.Split(new Char[] { '\\' });
filename = split[split.Length - 1].ToString();

System.IO.Stream strm = attachdoc.PostedFile.InputStream;
byte[] byt = new byte[Convert.ToInt32(attachdoc.PostedFile.ContentLength)];
strm.Read(byt, 0, Convert.ToInt32(attachdoc.PostedFile.ContentLength));
strm.Close();

// Open site where document library is created.
SPSite objSite = SPContext.Current.Site;
SPWeb objWeb = objSite.OpenWeb();
SPFolder mylibrary = objWeb.Folders["Project Documents"];

if (objWeb.GetFile("Project Documents/" + filename).Exists)
{
if (objWeb.GetFile("Project Documents/" + filename).CheckOutStatus == SPFile.SPCheckOutStatus.None)
{
objWeb.GetFile("Project Documents/" + filename).CheckOut();
}
else
{
flgPublish = false;
SPUser chkBy = objWeb.GetFile("Project Documents/" + filename).CheckedOutBy;
url = "checkedout";
lblLessonListError.Text = "Cannot upload the file. File is checked out by " + chkBy.LoginName;
trLessonListError.Visible = true;
}
}

if (flgPublish == true)
{
objWeb.AllowUnsafeUpdates = true;
SPFile spfile = mylibrary.Files.Add(System.IO.Path.GetFileName(filename), byt, true);

SPDocumentLibrary docs = (SPDocumentLibrary)objWeb.Lists[mylibrary.ContainingDocumentLibrary];
SPListItem item = docs.Items[spfile.UniqueId];
item["Project_x0020_Phase"] = "Metadata Text";
item.Update();

spfile.CheckIn("Checked in", SPCheckinType.MinorCheckIn);
objWeb.AllowUnsafeUpdates = false;
url = spfile.Item["Encoded Absolute URL"].ToString();
}

}
}


}
catch (Exception ex)
{
SW = File.AppendText("D:\\temp\\LogImport.txt");
SW.WriteLine(" Error Occurred : " + ex.Message + " User : " + SPContext.Current.Web.CurrentUser.ToString() + " " + DateTime.Now.ToString() + " " + ex.StackTrace);
SW.WriteLine("--------------------------------------------------");
SW.Close();
}

}


Leave the question, I will respond for any of your query.

Thanks
Sanjay Tiwari
s_tiwari05@yahoo.com