Dynamically changing MasterPages in SharePoint 2013 when using Device Channels

Suppose you have a public facing website that has about 40 different page layouts. You are also using the Device Channel functionality, which is new to SharePoint 2013. Basically this means you can set multiple MasterPages, one for each device channel you use. But what if you want to have a different MasterPage for one of the page layouts you use. You have to take into consideration, that when updating the MasterPage from the code behind file, the MasterPage is updated for any and all device channels you use. But what if you only want to change the MasterPage for a certain device channel, but keep the default for all others? That’s where this post comes in.

First let’s take a look at how you can change the MasterPage from the code behind file of a Page Layout. This post by Kirk Evans shows you how to deploy a Page Layout and how to create a code behind file for this Page Layout. This post by Eric Overfield gives us a hint on how to change the Masterpage from the code behind file. As noted, you can only change this property in the OnPreInit method, otherwise the MasterPage will have already loaded and changing the property would result in an error message. MSDN shows the following example:

This would however change the MasterPage for all device channels and remember that we only want to change this MasterPage for a specific device channel. This post advices you to use a HttpContext variable that is called ‘EffectiveDeviceChannel’. The post also warns that this property might not be available everywhere because it is loaded on demand. I have tried to use this property, but unfortunately, as you would have guessed, it was not yet available during the OnPreInit method so I had to find a different solution. Browsing the web didn’t do me any good, and since most of the Mobile classes in SharePoint are sealed, those weren’t of any help either. After inspecting the entire HttpContext, there was one property that I could ‘misuse’ and was the solution to my problem. The HttpContext.Current.Items[‘MasterPageUrl’] was there, and it was showing the URL to the MasterPage that was about to be loaded. Since the device channels all have different Masterpages, this became a solution for me to change the MasterPage only for a specific Page Layout. The code used for this is displayed below:

So, when changing the MasterPage from a Page Layout file when also using Device Channels – resort to using the HttpContext variable MasterPageUrl, because the EffectiveDeviceChannel variable is not yet loaded at that point in the life cycle. Gotcha!

Sequence Dropdown Box using javascript and HTML

Have you ever come across that scenario where you have more than a few input fields and you want to go the user the ability to sort these fields, without having to copy + paste the input several times? In these cases, multiple dropdown boxes next to the input fields specifying the order of these fields can be very useful. This got me thinking, “Well, doesn’t SharePoint already implement something like that, for example when modifying a list view?”. In this post I’ll describe how Microsoft has implemented this and how it can work for you. This example uses only javascript and html, so if you want to do some server side action with it, be sure to modify the code accordingly.

First off, here’s an example of modifying a list view, where you will find these dropdown boxes:


In order to retrieve the code that Microsoft uses for this, I’ve inspected the page and rebuild the same scenario. Here’s the pure HTML that is used:

As you can see, this is nothing fancy. Just a simple HTMLSelect item containing a few options. The onchange method calls a certain Javascript function. This javascript function does all the magic for us, and makes sure that all the other dropdown boxes get their values changed accordingly. The javascript that is used for this is:

The second value specified in this javascript call is the HTMLSelect number of your current item. So for the first dropdownbox, that would be item 0. For the second it would be item 1, etc. The third value is the number of dropdownboxes that are there in total.

So there you have it! A simple HTML and Javascript example of making your website that much more user friendly.