[whatwg] Proposed simplification to Microdata

Thu May 26 18:15:46 PDT 2011

On Thu, May 26, 2011 at 12:02 PM, Guha <guha at google.com> wrote:
> We are trying to simplify statement of a fairly common thing that crops up
> with microdata
>
> E.g.,
>
> Consider the block:
> 1) <div itemscope itemtype=”http://schema.org/Book”>
>      <span itemprop=”name”>The Catcher in the Rye</span> -
>     by <span itemprop=”hasAuthor”>J.D. Salinger</span>
>   </div>
>
> Now, the site wants to use the wikipedia (or freebase) entry for Salinger,
> just to be clear and wants the value of the  hasAuthor property to be an
> item with that ID.
> I believe the following says that:
>
> 2) <div itemscope itemtype=”http://schema.org/Book”>
>      <span itemprop=”name”>The Catcher in the Rye</span> -
>   by <a href="http://en.wikipedia.org/wiki/J._D._Salinger"
> itemprop=”hasAuthor”>J.D.
> Salinger</a>
>   </div>
>
> Often, the site does not want to link out to the wikipedia (or other
> canonical url) page, but only specify
> it in the microdata. This can be done by:
>
> 3) <div itemscope itemtype=”http://schema.org/Book”>
>     <span itemprop=”name”>The Catcher in the Rye</span> -
>   by <span itemscope
> itemid="http://en.wikipedia.org/wiki/J._D._Salinger"
> itemprop=”hasAuthor”>J.D.
> Salinger</span>
>  </div>

No, that's invalid:
"The itemid attribute must not be specified on elements that do not
have both an itemscope attribute and an itemtype attribute specified,
and must not be specified on elements with an itemscope attribute
whose itemtype attribute specifies a vocabulary that does not support
global identifiers for items, as defined by that vocabulary's
specification."

The correct way to solve this case is with markup like this:

<div itemscope itemtype="http://scheme.org/Book">
  <span itemprop="name">The Catcher in the Rye</span> -
  by J.D. Salinger
  <link itemprop="hasAuthor" href="http://en.wikipedia.org/wiki/J._D._Salinger">
</div>

~TJ