Embedded types
So far you have described the page using a single type and a handful
properties. However, when you added the @property="author"
attribute, the expected value for the property (the range) was
not a simple text string; it was supposed to be an entity of either the
Person or the Organization type.
In this exercise, you will add several embedded entities to the page to
conform to the vocabulary definition and make your structured data
even more useful.
Continue working with the HTML file that you have been editing so far,
or for a fresh start, copy ../1_book/step2/check_c.html into a new file.
Define the Person entity
Your @property="author" attribute needs to define a
Person entity to satisfy the expected value of
author. Simply add the @typeof="Person"
attribute to the same HTML element so that you are, in one step,
defining the author attribute for the overall
Book entity, while simultaneously starting a new
Person entity scope.
Check your markup
<!DOCTYPE html>
...
<body vocab="http://schema.org/" typeof="Book">
...
<tr valign="top">
<th>Autor:</th>
<td class="recordAuthor" property="author" typeof="Person">
<a href="/Author?lookfor=%22Herzberg%2C+Agnes+M%22">Herzberg, Agnes M</a>
</td>
</tr>
<tr valign="top">
<th>Weitere Autoren:</th>
<td class="recordSecAuthor" property="author" typeof="Person">
<a href="/Author?lookfor=%22Andrews%2C+David+F%22">Andrews, David F</a>
</td>
</tr>
...
Define basic properties of the Person entity
Now that you have defined a Person entity, you can define
specific properties for it.
Declare that the person's name is the name property of the
Person entity.
Tip: Remember that you might need to add
<span> tags to create a new scope for the properties
that you want to add.
Check your markup
<!DOCTYPE html>
...
<body vocab="http://schema.org/" typeof="Book">
...
<tr valign="top">
<th>Autor:</th>
<td class="recordAuthor" property="author" typeof="Person">
<span property="name">
<a href="/Author?lookfor=%22Herzberg%2C+Agnes+M%22">Herzberg, Agnes M</a>
</span>
</td>
</tr>
<tr valign="top">
<th>Weitere Autoren:</th>
<td class="recordSecAuthor" property="author" typeof="Person">
<span property="name">
<a href="/Author?lookfor=%22Andrews%2C+David+F%22">Andrews, David F</a>
</span>
</td>
</tr>
...
Declare that the same Person is both the author and copyrightHolder
Copyright is an important subject for both creators and organizations
and individuals seeking to reuse or republish work, so naturally
schema.org includes a copyrightHolder property that you
can apply. In this case, however, the author and the copyrightHolder
are one and the same, and you have already used the
@property attribute.
To define multiple property values for the same attribute, simply
include the values as a whitespace-delimited list. In this case, edit
the HTML to declare @property="author copyrightHolder"
and check your work in one or more structured data validators.
Note: These are still relatively early days for structured
data validators, and their output varies for more esoteric cases
like multi-valued attributes. For example, the Structured Data Linter
recognizes the second value for copyrightHolder but
generates a "blank node" identifier for it, whereas Google's
Structured Data Testing Tool only recognizes the last value of the
multi-valued attribute. To complicate matters further, the search
engines recognize that their tools have bugs that differ from what
their actual production parser understands... so don't be overly
alarmed if it seems like your markup is not being recognized by the
testing tool.
Use the @resource attribute to group assertions for an entity
Sometimes your HTML document does not group all of the content in such
a way that you can cleanly keep all of the attributes for a given
instance of an entity within a single scope. In these cases, you may be
able to use the @resource attribute to logically group the
properties for that instance.
For example, when you added the @typeof="Person"
declaration for the author, the name of the author was separated from
your existing Person instance by the <a>
element in the middle. The new scope that that <a>
introduces makes it a bit more difficult to mark up the
familyName and givenName of the author.
To resolve the problem, add a @resource attribute
to your existing Person declaration. The value of the new
attribute should be unique on this page; use #author1
for the sake of simplicity.
Then add a wrapping <span> element around the
name of the author inside the a element, including a
@resource attribute with a value of #author1 to match
what you added above. This creates a new scope for the existing entity,
such that any properties declared within this new scope will be added to that
entity.
Now add another <span> element inside the newly scoped
#author1 resource, and declare it to be the
name property. For bonus points, you can
nest the givenName and familyName
properties inside of the name property.
Check your markup
<!DOCTYPE html>
...
<body vocab="http://schema.org/" typeof="Book">
...
<tr valign="top">
<th>Autor:</th>
<td class="recordAuthor" property="author copyrightHolder" typeof="Person" resource="#author1">
<a href="/Author?lookfor=%22Herzberg%2C+Agnes+M%22">
<span resource="#author1">
<span property="name">
<span property="familyName">Herzberg</span>,
<span property="givenName">Agnes M</span>
</span>
</span>
</a>
</span>
</td>
</tr>
...
Describe the publisher as an Organization type
So far we have not provided any value for the publisher
property, which tends to be important for creative works. The publisher documentation shows
that the expected range is Organization, which in turn
has child types such as Corporation.
- Define a new
Corporation entity with the name of the
publisher as the name property.
- Add a
location property for the
Corporation entity. Notice that the expected range is a type of
either Place or PostalAddress. Use a
PostalAddress entity, filling in the addressLocality
and addressRegion properties.
Check your markup
<!DOCTYPE html>
...
<body vocab="http://schema.org/" typeof="Book" resource="#book">
...
<tr valign="top">
<th>Veröffentlicht:</th>
<td>
<span property="publisher" typeof="Corporation">
<span property="location" typeof="PostalAddress">
<span property="addressLocality">New York</span> [u.a.]
</span> : <span property="name">Springer</span>,
</span>
<time property="datePublished">1985</time>
</td>
</tr>
...
Bonus exercise: Add a second author of type Person
There is a second author for this book, David Andrews, that should
be reflected in the machine-readable markup.
- Define the new
Person entity with the name,
givenName, and familyName properties.
Check your markup
<!DOCTYPE html>
...
<body vocab="http://schema.org/" typeof="Book">
...
<tr valign="top">
<th>Weitere Autoren:</th>
<td class="recordSecAuthor" property="author copyrightHolder" typeof="Person" resource="#author2">
<a href="/Author?lookfor=%22Andrews%2C+David+F%22">
<span resource="#author2">
<span property="name">
<span property="familyName">Andrews</span>,
<span property="givenName">David F</span>
</span>
</span>
</a>
</span>
</td>
</tr>
...
Checkpoint: Your HTML page should now look like ../1_book/step3/check_d.html
Lessons learned
In this exercise, you learned:
- How to embed entities within properties
- How to declare multiple property values in a single
@property attribute
- How to use
@resource to group assertions for a single entity on a page
