How to retrieve JSON embedded in HTML comments using XPATH?

Question

I have HTML output of the form:

<!-- wp:uagb/section {"block_id":"e00ee750-246d-46fd-a034-c6dc37497309","contenttype":"exercise","contenttitle":"here is exercise 1","contentname":"Exercise"} -->
<div id="here-is-exercise-1" class="contenttype-wrapper sometopictype-exercise" data-id="e00ee750-246d-46fd-a034-c6dc37497309">
<!-- wp:paragraph -->
   <p>Some stuff</p>
<!-- /wp:paragraph -->
</div>
<!-- /wp:uagb/section -->

So you have these comments that start with <!-- wp:uagb/section and in those comments you have JSON of form

{"block_id":"e00ee750-246d-46fd-a034-c6dc37497309","contenttype":"exercise","contenttitle":"here is exercise 1","contentname":"Exercise"}

I am trying to form an XPATH query (in PHP) that is of form

"Get me all JSON objects that contain parameter `contenttype`"

I am pretty proficient with XPATH when it comes to normal DOM extraction, but not quite sure how to go about this. Ideas?

Is your desired output the whole first comment or just the word `exercise'? — Jack Fleeting
– Jack Fleeting, Commented Dec 7, 2019 at 11:44
Then the xpath expression in the first line of your answer (//comment()[contains(.,'contenttype')]) should work, why would you need the rest? — Jack Fleeting
– Jack Fleeting, Commented Dec 7, 2019 at 14:33
If I just call xpath that way, won't it also return the text 'wp:uagb/section' in returned output? — Brian
– Brian, Commented Dec 7, 2019 at 16:05

Brian · Accepted Answer · 2019-12-07 10:08:34Z

0

Ok, based on this post

Extracting Comments from HTML code using Xpath

here is what I came up with:

$contenttypes = $xpath->query("//comment()[contains(.,'contenttype')]");
foreach ($contenttypes as $contenttype) {
    preg_match_all("/\\{(.*?)\\}/", $contenttype->data, $matches);
    $data = json_decode(trim($matches[0][0], '"'));

And then the data I need is in that $data variable. Didn't realize that xpath has built in support for comments!

I am sure someone has a way to get the JSON object in one xpath query. I couldn't figure that out so just went with preg_match_all.

answered Dec 7, 2019 at 10:08

Brian

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