amphtml: SDTT errors on template[type=amp-mustache]

Google Structured Data Testing (GSDTT) validates JSON-LD and is a proxy for Google Knowledge Graph. Our goal is to inject an AMP document with JSON-LD using amp-list and amp-mustache.

Here is sample JSON-LD:

{
  "@context": "http://schema.org",
  "@type": "WebSite",
  "@id": "#website",
  "url": "https://afdsi.org/",
  "name": "Structured Data Provider",
  "potentialAction": {
    "@type": "SearchAction",
    "target": "https://afdsi.org/?s={search_term_string}",
    "query-input": "required name=search_term_string"
  }
}

And as a string:

{"@context":"http://schema.org","@type":"WebSite","@id":"#website","url":"https://afdsi.org/","name":"Structured Data Provider","potentialAction":{"@type":"SearchAction","target":"https://afdsi.org/?s={search_term_string}","query-input":"required name=search_term_string"}}

JSON-LD string is valid on GSDTT

Our conventional technique uses jQuery. Here is a working example in a non-AMP page: https://afdsi.org/index.html Click link to Google’s Structured Data Testing Tool. See results on lower left.

Our first amp-list step is to transform JSON-LD into amp-list format (verified to be valid JSON)

{"items":[
{"link":"{\"@context\":\"http://schema.org\",\"@type\":\"WebSite\",\"@id\":\"#website\",\"url\":\"https://afdsi.org/\",\"name:Structured Data Provider\",\"potentialAction\":{\"@type\":\"SearchAction\",\"target\":\"https://afdsi.org/?s=?{search_term_string}\"}}"}
]}

Example is rendered here: https://afdsi.org/amp-list-03/ Page is valid AMP. When rendered on GSDTT: https://search.google.com/structured-data/testing-tool#url=https%3A%2F%2Fafdsi.org%2Famp-list-03%2F we see the following:

"Uncategorized error"
<script type="application/ld+json">
  {{link}}
</script>

{{link}} is highlighted

For us, this is a severity-1 issue; we have no work-around and cannot achieve the result we customarily achieve using jQuery in a non-AMP page.

Are we doing something wrong? Is there a work-around that enables an AMP page, using amp-list, to inject JSON-LD and to be harvested – as is achieved with the jQuery example?

Aside: Microdata or RDFa is not an acceptable work-around 😉

We see these discussions: https://github.com/ampproject/amphtml/issues/6229#issuecomment-408954289 https://github.com/ampproject/amphtml/pull/16782