Rails "The parameter passed to #in? must respond to #include?"

Question

作为此处另一个问题的跟进，我已将以下代码添加到我的 records_controller.rb

if params[:order].in? %s[year artist title]
  # adds ORDER to the scope
  @records.merge!( Record.order("? DESC", params[:order]) )
end

但是我得到一个错误：

"The parameter passed to #in? must respond to #include?"

这是什么意思？我需要改变什么？

Answer 1

%s[year artist title]
=> :"year artist title"

这是一个符号，我猜你想检查 param 是否是字符串之一。尝试使用 %w 代替。

if params[:order].in? %w[year artist title]

Answer 2

来自documentation：

in?(another_object) public

Returns true if this object is included in the argument.

Argument must be any object which responds to #include?

include? 响应应为 %w[year artist title] 格式的对象数组，而不是像您编写的符号 %s[year artist title]

%w[year artist title] # => ["year", "artist", "title"] can be used for include? and in?
%i[year artist title] # => [:year, :artist, :title] can be used for include? and in?

%s[year artist title] # => :"year artist title" which is a symbol that can not be used for include? or in?

Answer 3

另一种情况：

如果您的数组是 nil

，您将收到同样的错误

我遇到了同样的问题，但这是因为我没有为我的数组处理 nil：

my_string.in? my_array

如果my_array = nil我得到：(The parameter passed to #in? must respond to #include?)

为了解决这个问题，我刚刚更改了：

my_string.in? my_array || []

现在如果my_array = nil我得到了假

Rails "The parameter passed to #in? must respond to #include?"

Rails "The parameter passed to #in? must respond to #include?"

error-handling

ruby-on-rails

include

actioncontroller