Support multiple JSON fragments in HTML+XPath+JSON mode (#7369)

* Support multiple JSON fragments in HTML+XPath+JSON mode
fix https://github.com/FreshRSS/FreshRSS/discussions/7352#discussioncomment-12295475
E.g. HTML with one `<script type="application/ld+json">...</script>` per item.

* Better help messages

1 files changed, 19 insertions, 2 deletions

diff --git a/app/Models/Feed.php b/app/Models/Feed.php
index 57bf9d7a4..072948e1b 100644
--- a/app/Models/Feed.php
+++ b/app/Models/Feed.php
@@ -725,8 +725,25 @@ class FreshRSS_Feed extends Minz_Model {
 		}
 
 		$xpath = new DOMXPath($doc);
-		$json = @$xpath->evaluate('normalize-space(' . $xPathToJson . ')');
-		return is_string($json) ? $json : null;
+		$jsonFragments = @$xpath->evaluate($xPathToJson);
+		if ($jsonFragments === false) {
+			return null;
+		}
+		if (is_string($jsonFragments)) {
+			return $jsonFragments;
+		}
+		if ($jsonFragments instanceof DOMNodeList && $jsonFragments->length > 0) {
+			// If the result is a list, then aggregate as a JSON array
+			$result = [];
+			foreach ($jsonFragments as $node) {
+				$json = json_decode($node->textContent, true);
+				if (json_last_error() === JSON_ERROR_NONE && is_array($json)) {
+					$result[] = $json;
+				}
+			}
+			return json_encode($result, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) ?: null;
+		}
+		return null;
 	}
 
 	public function loadJson(): ?\SimplePie\SimplePie {