Tag Archives: Developer

SPFileVersion: Handling SharePoint file versions programmatically

I recently had a requirement around linking to and downloading specific versions of documents stored in SharePoint. There is some rather quirky behaviour around SPFileVersion and how this is achieved and I felt it warranted a post.

Versions

The first thing to be aware of is that there are two distinct version collections: SPFileVersionCollection and SPListItemVersionCollection. These collections can be accessed via the respective assets as you would expect (SPFile.Versions and SPListItem.Versions) and, as is the way in SharePoint, are enumerations of SPFileVersion and SPListItemVersion objects, respectively. These objects, which represent the individual versions, have a number of similar properties and methods but do not share a base class nor an interface.

In order to access specific versions of documents, the approach I took was to store the VersionLabel (a property on both SPFileVersion and SPListItemVersion) and then retrieve the version by using this value in conjunction with GetVersionFromLabel (a method on both SPFileVersion and SPListItemVersion). This works but with a number of caveats:

  1. SPFileVersionCollection does NOT contain an entry for the latest version. This means that if the document has only a single version then this collection will be empty. If you want to access the latest version you must verify that the version label refers to the latest version by comparing it to the first entry in the SPListItemVersionCollection and if it is then access the SPFile directly. If you are accessing properties that are also present on an SPListItemVersion (ie not opening a stream) you can use that collection instead but you must also take note of the next point.
  2. SPListItemVersion.Url behaves unexpectedly in some situations. Assumedly this is to support directing underprivileged users away from minor versions that they are not allowed to see (although I don’t see how it achieves this), the Url for minor versions will be equal to that of the latest minor version when there is no published version. Always use SPFileVersion.Url.
  3. Minor versions get promoted when published, breaking links to the minor version. Example – You have a document currently at version 0.2, with a previous 0.1 version. When you publish this document you still only have two versions: 0.1 and 1.0. You will now fail to locate version 0.2. Don’t be fooled into thinking that using the VersionId property will solve this issue. It simply represents the the version label as an integer (+1 for each minor version, +512 for each major version). The only way I could find to handle this case is to introduce the doc store version which is stored in the property bag of the SPFile: SPFile.Properties["vti_docstoreversion"]. You can see how this works by looking at the code examples I have included but if this specific case isn’t going to be an issue for you then don’t use it and enjoy cleaner code (see here). Also note that the doc store version is only stored in the SPFile property bag and not in the SPListItem property bag.

I have included some code to illustrate how this may be implemented:

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Visual Studio Developer Tips

Visual Studio is an excellent IDE for working with Microsoft technologies. However, it isn’t perfect and can crash or hang from time to time. After experiencing an issue with the IDE during a debugging session recently, I came across a setting which improved my Visual Studio experience and thought it was time to bring together some of my favourite tips.

 

1.       Navigate To (CTRL+COMMA)

This outstanding useful key combination brings up the ‘Navigate To’ dialog which allows you to find almost anything -files, classes, methods, properties. It is so easy and so fast that, IMO, it should be used instead of the Solution Explorer whenever you know the name of anything you are looking for.

NavigateTo
The “Navigate To…” dialog

 

2.       Debug > Delete All Breakpoints (CTRL+SHIFT+F9)

Regularly deleting all breakpoints can greatly improve you debugging experience within VS. The performance impact upon attaching to a process per of individual breakpoint is negligible. However, after some time, presumably accelerated by merging from source control, the solution can become corrupt (I use the term ‘corrupt’ tentatively because the solution is still functional) such that loading symbols upon attaching to a process can take an exceptionally long time. Deleting all breakpoints (using the command, not individually) refreshes all references and fixes this issue.

 

3.       Solution Explorer Collapse And Sync (Solution Explorer Tools in VS2010)

Installing this VS add-on provides what can be very useful macros for the solution explorer depending on how you use it. It provides functionality such as ‘close all branches’ and ‘open to the current branch’.

The Solution Explorer Tools toolbar

You can find it here.

Personally, I quite like the built-in ‘Tools > Options > Projects and Solutions > General > Track Active Item In Solution Explorer’ which ensures that the solution explorer is always open to currently active file, but I know a lot of users will hate the way it jumps about.

 

4.       Dark Themes

Even with relatively fresh young eyes, staring at a white screen is painful after a few long sessions. Bring on the dark themes. Using a theme with a dark grey background saves my eyes and keeps me in the zone! There are many great ones and a handy designer for creating your own. With the release of VS2012 there is now even greater granular semantic colourisation.

“Son of Obsidian” from StudioStyles

 

5.       Deactivate Implicit Property Evaluation

Tools > Options > Debugging > General > (uncheck) “Enable property evaluation and other implicit function calls”

The impact of this is that properties aren’t evaluated unless you inspect them individually (explicitly). This means that you can no longer view all properties on an object by calling it in the immediate window – you have to inspect properties one-by-one. As SharePoint objects have dozens of properties this can make a noticeable difference when debugging SharePoint code. As such, your mileage may vary depending on what you are debugging and the relative performance of your debugging environment.

 

6.       Integrate Third Party Diff Tool

You can swap in external programs to perform your file merging and file diffing activities. Personally, I think that WinMerge is fantastic, especially after fine tuning the comparison settings (e.g. skip white space, block detection, etc.), but whatever you find is your favourite utility for these actions it almost certainly isn’t the default. Paul Bouwer has already blogged in detail about how to plug it in:

WinMerge in action

These are tips that I expect to be useful for nearly any developer working with Visual Studio. Depending on what you are working on it is always worth a quick web search to see what else is out there to aid your efforts and help you work smarter.

With Windows 8 and SharePoint Apps being a development focus, the web development improvements in VS2012 will be obvious. It also includes SharePoint asset designers, a SharePoint profiler and more built in SharePoint templates among many other features.