Schema.org and object hierarchy

问题

Actually I have a lack of understanding of how Schema.org objects are "composed" out of the given specification. Unfortunately I found no clear explanation so far.

Let’s take the JSON-LD example given at https://schema.org/SoldOut. In "Example 1" we have given a property offers of type Offer. Within the only Offer, there is a price property specified ("13.00").

But if I look at the specification of object Offer given at https://schema.org/Offer there is no price property specified at all.

So my question is, where does it come from - the price property? It seems that the Offer object merges the types Offer and PriceSpecification. But why isn’t it then mentioned there in the @type property?

回答1:

There are two kinds of price-property could be coming:

The first kind is the kind shown in the example of SoldOut. The second kind i show you in the following example, based on the SoldOuttoo

<script type="application/ld+json">
{
    "@context": "http://schema.org",
    "@type": "Event",
    "location": {
        "@type": "Place",
        "address": {
        "@type": "PostalAddress",
        "addressLocality": "Denver",
        "addressRegion": "CO",
        "postalCode": "80209",
        "streetAddress": "7 S. Broadway"
        },
        "name": "The Hi-Dive"
    },
    "name": "SOLD OUT! Typhoon with Radiation City",
    "offers": {
        "@type": "Offer",
        "availability": "http://schema.org/SoldOut",
        "price": {
            "@type": "PriceSpecification",
            "price": "13.00",
            "priceCurrency": "USD",
        },
        "url": "http://www.ticketfly.com/purchase/309433"
    },
    "startDate": "2013-09-14T21:30"
}
</script>

To say it in words, you could use price as stand-alone property, or as a part of the type PriceSpecification too. Both kinds of use are OK, the usage as a part of the type PriceSpecification is for cases, where you have to specify more properties as only the price and its currency, as listed under https://schema.org/PriceSpecification.

回答2:

But if I look at the specification of object Offer given at https://schema.org/Offer there is no price property specified at all.

The Offer type does specify the price property.

The price property is listed on https://schema.org/Offer, and the Offer type is also listed under "Used on these types" on https://schema.org/price.

(Sometimes there’s a bug where a type page doesn’t list all properties, so maybe that’s why you didn’t see it.)

A type always specifies the properties of itself and the properties of all its parent types. So for Offer, you can use the properties from Offer, from Intangible, and from Thing:

Thing > Intangible > Offer

All available properties are listed in the first table on the type’s pages (unless the bug hits).

来源：https://stackoverflow.com/questions/51019612/schema-org-and-object-hierarchy

标签

schema.org