api: Fix incomplete docs for ApiPageSet::$mRequestedPageFields

Unfortunately Phan gets super confused here, which is why I had to
split this off from I454baef. While it might be possible to silence
Phan I think the better solution is to get rid of the problematic
null initialization. The null is never used for anything, anywhere.
The contrary. In ApiPageSet::processDbRow() the null values are
accessed with an array operator as if they are arrays, which
(currently) forces PHP to silently initialize it to actually be
an empty array. Instead I suggest to make this magic behavior
explicitely visible.

Change-Id: If7c4f49e46cc6050942611a7b2bca46ea550b31c

1 files changed, 7 insertions, 7 deletions

diff --git a/includes/api/ApiPageSet.php b/includes/api/ApiPageSet.php
index dc440527d00b..d4347ce47d91 100644
--- a/includes/api/ApiPageSet.php
+++ b/includes/api/ApiPageSet.php
@@ -154,7 +154,7 @@ class ApiPageSet extends ApiBase {
 	/** @var string */
 	private $mCacheMode = 'public';
 
-	/** @var array */
+	/** @var array<string,array<int,mixed>> [fieldName][pageId] => value */
 	private $mRequestedPageFields = [];
 
 	/** @var int */
@@ -386,17 +386,17 @@ class ApiPageSet extends ApiBase {
 	/**
 	 * Request an additional field from the page table.
 	 * Must be called before execute()
-	 * @param string $fieldName
+	 * @param string $fieldName A page table field, e.g. "page_touched"
 	 */
 	public function requestField( $fieldName ) {
-		$this->mRequestedPageFields[$fieldName] = null;
+		$this->mRequestedPageFields[$fieldName] = [];
 	}
 
 	/**
-	 * Get the value of a custom field previously requested through
-	 * requestField()
-	 * @param string $fieldName
-	 * @return mixed Field value
+	 * Get the values of one of the previously requested page table fields. Can only be used
+	 * after execute() and only for fields previously requested through requestField().
+	 * @param string $fieldName A page table field, e.g. "page_touched"
+	 * @return array<int,mixed> Field values per page id, initialized only after execute()
 	 */
 	public function getCustomField( $fieldName ) {
 		return $this->mRequestedPageFields[$fieldName];