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In EPiServer 7 you can limit what page types can be selected in a page or link collection property using validation attributes.
One of the big problems with EPiServer sites that have lived a while is when some clever editor decides to change a page property. It just so happens that this specific page property is used to get a page of a specific page type that contains some important properties that are used for settings/header/footer/search page etc. For example a page property on the start page that links to a settings page gets changed to an article page. This might result in the whole site crashing. Arghhh…
In EPiServer 7 we get to create our own validation attributes, so why not create a validation attribute that prevents the user from selecting the wrong page type?
I have created such an validation attribute. Simply add this class to your project and you can start using it. You can find the source code at the end of this article
Lets say we have a settings page in our solution and we have a page property that points to the search page for our site. We want to ensure that only a page of the page type “SearchPage” can be selected.
If we try to select the page “Management” of type “StandardPage” we will get the following error:
You can also use inheritance, so if you limit the page property to “StandardPage” you can select a page of the type of “StandardPage” or any page inherited from “StandardPage” like “NewsPage” and “ProductPage”.
You are not limited to page types, you can also specify an interface to only allow page types that implements a specific interface to be selectable. This ensures that the properties defined in the interface will be included in the selected page.
The validation attribute also works on the LinkItemCollection property and it checks that all the items are EPiServer pages of the correct page type. In this example we only want to have a list of contact pages of the type “Contactpage”.
The built in validation attributes like StringLength, Range and RegularExpression are really powerful in validating the input from editors, especially when you need to use it for something more than just displaying the value. This power can be further extended with custom validation attributes like the one in this blog post. I am sure more validators will be released by the community as EPiServer 7 matures.
For the examples in the blog post to work you need to create an empty class in your project and copy and paste the code below inside.