ruby-on-rails - :Condition 语句和 Ruby Rails

Question

我正在尝试使这些语句起作用：

@all_ratings = ["G","PG","PG-13","R"]
@valid_ratings = params["ratings"]
@movies = Movie.find(:all ,  :conditions => {@valid_ratings[:rating.upcase] => "1"}   )

但我收到错误：

undefined method `to_sym' for nil:NilClass

当我应该得到一场比赛时。

一个示例输入是：

"ratings"=>{"PG-13"=>"1"}

我哪里错了？

---

更多信息：

该表有标题、发布日期和评分三个字段，非常简单。评级选项在上面的 中进行了说明@all_ratings。

Answer 1

它告诉你，你@valid_ratings在nil

你可能正在尝试这样做？

@valid_ratings = Rating.find(params["ratings"])

Answer 2

导轨 3.x：

@all_ratings = ["G","PG","PG-13","R"]
@valid_ratings = params["ratings"]
# Is @valid_ratings the same as you example, "ratings"=>{"PG-13"=>"1"}?
# It would be easiest to pass a subset of @all_ratings such that the params
# get converted to something like this: "ratings"=>["G", "PG"]
Movie.where(:rating => valid_ratings).all
# SQL: SELECT * FROM movies WHERE rating IN ('G','PG')

我不确定你想做什么:rating.upcase。是否有一个名为 rating 的变量？:rating是一个符号。upcase不是符号上的方法。