Ruby在WHERE子句中使用带有多个选项的查询

我想提出一个更好的建议。。。更好地使用ruby功能。谁能给我一个更好的解决方案来组合这个查询

@conditions = ""
if(ratings["G"] == "1")
  @conditions += " 'G' "

end
if(ratings["PG"] == "1")
  @conditions += " OR rating = 'PG' "

end
if(ratings["PG-13"] == "1")
  @conditions += " OR rating = 'PG-13' "

end
if(ratings["R"] == "1")
  @conditions += " OR rating = 'R' "

end

@movies = Movie.where("rating = "+ @conditions)

return @movies

---

非常感谢，

虽然@xdazz answer更干净，但这种方法返回所需的输出

Movie.where(:rating => ratings.select({|k,v| v == "1"}).keys)

@conditions = ""
ratings.each do |k, v|
  @conditions << (@conditions.empty? ? "rating = '#{k}'" : " OR rating = '#{k}'") if v == "1"
end
@movies = Movie.where(@conditions)

而上述方法将返回更类似SQL的字符串：

p @conditions 
# => "rating = 'G' OR rating = 'PG' OR rating = 'PG-13' OR rating = 'R'"

最后，@xdazz方法可以重写为以下内容，以获得相同的输出：

p "rating = '" + ratings.select { |k,v| v == "1" }.keys.join("' OR rating = '") + "'"
# => "rating = 'G' OR rating = 'PG' OR rating = 'PG-13' OR rating = 'R'"

编辑2:

---

为了弄清楚，如果最初的问题是关于Rails的，那么应该使用@xdazz答案。

请您帮助解释一下，这得到的是完整对象，而zdazz只是键，这有什么区别吗？如果xdazz没有钥匙会怎么样？嗯，我有！谢谢你们！如果可能，请详细介绍.key的使用。谢谢

p "rating = '" + ratings.select { |k,v| v == "1" }.keys.join("' OR rating = '") + "'"
# => "rating = 'G' OR rating = 'PG' OR rating = 'PG-13' OR rating = 'R'"