Fix JSON export/import (#5626)

* Fix import with empty content
fix https://github.com/FreshRSS/FreshRSS/issues/5622
Cherry picks on https://github.com/FreshRSS/FreshRSS/pull/5584

* Fix export of tags / labels
Article-defined tags were wrongly exported as user-defined labels.

* Fix export of tags / labels
Article-defined tags were wrongly exported as user-defined labels.

* Fix bug with many labels

* Better typing

* Comments

2 files changed, 15 insertions, 7 deletions

diff --git a/app/Models/Entry.php b/app/Models/Entry.php
index 7da27e409..b70e7e2ab 100644
--- a/app/Models/Entry.php
+++ b/app/Models/Entry.php
@@ -846,12 +846,12 @@ HTML;
 
 	/**
 	 * N.B.: To avoid expensive lookups, ensure to set `$entry->_feed($feed)` before calling this function.
-	 * N.B.: You might have to populate `$entry->_tags()` prior to calling this function.
 	 * @param string $mode Set to `'compat'` to use an alternative Unicode representation for problematic HTML special characters not decoded by some clients;
 	 * 	set to `'freshrss'` for using FreshRSS additions for internal use (e.g. export/import).
+	 * @param array<string> $labels List of labels associated to this entry.
 	 * @return array<string,mixed> A representation of this entry in a format compatible with Google Reader API
 	 */
-	public function toGReader(string $mode = ''): array {
+	public function toGReader(string $mode = '', array $labels = []): array {
 
 		$feed = $this->feed();
 		$category = $feed == null ? null : $feed->category();
@@ -935,8 +935,11 @@ HTML;
 		if ($this->isFavorite()) {
 			$item['categories'][] = 'user/-/state/com.google/starred';
 		}
+		foreach ($labels as $labelName) {
+			$item['categories'][] = 'user/-/label/' . htmlspecialchars_decode($labelName, ENT_QUOTES);
+		}
 		foreach ($this->tags() as $tagName) {
-			$item['categories'][] = 'user/-/label/' . htmlspecialchars_decode($tagName, ENT_QUOTES);
+			$item['categories'][] = htmlspecialchars_decode($tagName, ENT_QUOTES);
 		}
 		return $item;
 	}
diff --git a/app/Models/TagDAO.php b/app/Models/TagDAO.php
index 0704fd9f7..80a0e7688 100644
--- a/app/Models/TagDAO.php
+++ b/app/Models/TagDAO.php
@@ -383,7 +383,11 @@ SQL;
 				// Split a query with too many variables parameters
 				$idsChunks = array_chunk($entries, FreshRSS_DatabaseDAO::MAX_VARIABLE_NUMBER);
 				foreach ($idsChunks as $idsChunk) {
-					$values += $this->getTagsForEntries($idsChunk);
+					$valuesChunk = $this->getTagsForEntries($idsChunk);
+					if (!is_array($valuesChunk)) {
+						return false;
+					}
+					$values = array_merge($values, $valuesChunk);
 				}
 				return $values;
 			}
@@ -419,9 +423,10 @@ SQL;
 	}
 
 	/**
-	 * For API
-	 * @param array<FreshRSS_Entry|numeric-string> $entries
-	 * @return array<string,array<string>>
+	 * Produces an array: for each entry ID (prefixed by `e_`), associate a list of labels.
+	 * Used by API and by JSON export, to speed up queries (would be very expensive to perform a label look-up on each entry individually).
+	 * @param array<FreshRSS_Entry|numeric-string> $entries the list of entries for which to retrieve the labels.
+	 * @return array<string,array<string>> An array of the shape `[e_id_entry => ["label 1", "label 2"]]`
 	 */
 	public function getEntryIdsTagNames(array $entries): array {
 		$result = [];