Firebase在数组中查询数据

Question

如果我向firebase数据库发出此查询，我可以看到数据

https://movielen4.firebaseio.com/movieLens/movies.json?orderBy="year"&equalTo=1990

JSON的片段：

"586": {
    "genre": ["Children's", "Comedy"],
    "title": "Home Alone ",
    "year": 1990
},
"3773": {
    "genre": ["Comedy"],
    "title": "House Party ",
    "year": 1990
},
"3661": {
    "genre": ["Horror", "Sci-Fi", "Thriller"],
    "title": "Puppet Master II ",
    "year": 1990
},

但是如果我将查询更改为

https://movielen4.firebaseio.com/movieLens/movies.json?orderBy="genre"&equalTo="Comedy"

它会返回空结果，即使你可以看到我有数据。我的索引定义正确

{
  "rules": {
    "movieLens" : {
      "movies" : {
        ".indexOn": ["genre", "year"]
      },
      "ratings": {
        ".indexOn": ["movieId", "rating", "userid", "timestamp"]
      },
      "users": {
        ".indexOn": ["age", "gender", "occupation", "userId", "zipCode"]
      }
    },
    ".read": true,
    ".write": true        
  }
}

我认为我看到空的结果，因为Genre是一个数组。查询成功一年，因为它只是一个值。有谁知道如何查询数据何时进入数组？