関連ワード:  php check if key in array exists    php check if key exists in array of objects    php check if key value exists in array    php test if key exists in array    php check if array key exists and has value    php check if key exists in multidimensional array    php check if key exists in associative array    php check if key value pair exists in array    php check if nested array key exists    php check if key value exists in multidimensional array