Second Life of a Hungarian SharePoint Geek

October 1, 2015

The SharePoint Time Machine

Filed under: SP 2013, Tips & Tricks — Tags: , — Peter Holpar @ 22:06

Assume you have a SharePoint list with a lot of items. The list supports versioning and you should provide a snapshot of the items at a given time in the past.

As you know, the Versions property (of type SPListItemVersionCollection) of the SPListItem class contains the item versions. One can access a specific version via the indexer property of the collection, by the ID of the version (where the ID = 512 * major version number + minor version number), or by the version number (a.k.a. label, for example, 2.3), but there is no direct support to get the actual version at a specific time in the past.

To achieve my goal, I’ve implemented the GetVersionFromDate extension method, that iterates through the method, and returns the version we need based on its creation date:

  1. public static SPListItemVersion GetVersionFromDate(this SPListItemVersionCollection versions, DateTime localDate)
  2. {
  3.     SPListItemVersion result = null;
  4.  
  5.     if (versions != null)
  6.     {
  7.         DateTime date = versions.ListItem.Web.RegionalSettings.TimeZone.LocalTimeToUTC(localDate);
  8.  
  9.         SPListItemVersion prevVersion = null;
  10.  
  11.         // versions[0] – current item version
  12.         // versions[versions.Count – 1] – first item version created
  13.         for (int i = versions.Count – 1; i >= 0; i–)
  14.         {
  15.             SPListItemVersion version = versions[i];
  16.             if (version.Created > date)
  17.             {
  18.                 result = prevVersion;
  19.                 break;
  20.             }
  21.             // if it is the last (actual) version and there is no result yet,
  22.             // then the date specified should be greater than the creation date of the last version
  23.             // we take the last version
  24.             else if (i == 0)
  25.             {
  26.                 result = version;
  27.             }
  28.  
  29.             prevVersion = version;
  30.         }                
  31.  
  32.     }
  33.  
  34.     return result;
  35. }

Note, that the Created property stores the creation date as UTC time, that we should convert first.

Using this method accessing the specific version is so simple as:

  1. SPList list = web.Lists["Your List"];
  2. SPListItem item = list.Items.GetItemById(1);
  3.  
  4. DateTime date = DateTime.Parse("2015/06/29 13:40");
  5. SPListItemVersion version = item.Versions.GetVersionFromDate(date);
  6. Console.WriteLine(version["APropertyName"]);

If you go through the items in the list and get the version of the specific time, you already have the required snapshot.

Advertisements

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Create a free website or blog at WordPress.com.

%d bloggers like this: