Friday, October 10, 2014

Invalid apex:attribute name values

The apex:attribute component in Visualforce allows developers to pass custom Apex class instances as attributes from the parent component or page to the child component. In this manner, it's possible to pass a page controller itself as an attribute to a component on the page, using a simple self property like the following.

public CustomController getSelf() {
    return this;

What the documentation doesn't say is that apparently (at least in Winter '15, API 32.0) there are keywords to avoid when naming your attribute, even though the Visualforce parser will not tell you there's a problem.

Trying to name your attribute "controller" will cause something like the following error to appear when saving a page: Wrong type for attribute <c:buggersitepaypalcheckout controller="{!self}">. Expected BuggerSiteSimpleSelfRegController, found String

Trying to name your attribute "parent" will cause a completely blank error message to appear when saving a page. But it's an error that will prevent you from saving your page, nonetheless.

Do you know any other hidden no-no's with naming apex:attribute elements? Please share so that we can all avoid these frustrating quirks int he future.