在rails helper方法where（）查询中使用变量列名

Question

I'm working with a User model that includes booleans for 6 days

[sun20, mon21, tue22, wed23, thur24, fri25]

with each user having option to confirm which of the 6 days they are participating in.

I'm trying to define a simple helper method:

  def day_confirmed(day)
    User.where(day: true).count
  end

where I could pass in a day and find out how many users are confirmed for that day, like so:

day_confirmed('mon21')

My problem is that when I use day in the where() , rails assumes that I'm searching for a column named day instead of outputting the value that I'm passing in to my method.

Surely I'm forgetting something, right?

Answer 1

This syntax:

User.where( day: true )

Is equivalent to:

User.where( :day => true )

That's because using : in a hash instead of => , eg { foo: bar } , is the same as using a symbol for the key, eg { :foo => bar } . Perhaps this will help:

foo = "I am a key"

hsh = { foo: "bar" }
# => { :foo => "bar" }

hsh.keys
# => [ :foo ]

hsh = { foo => "bar" }
# => { "I am a key" => "bar" }

hsh.keys
# => [ "I am a key" ]

So, if you want to use the value of the variable day rather than the symbol :day as the key, try this instead:

User.where( day => true )

Answer 2

If these are your column names, [sun20, mon21, tue22, wed23, thur24, fri25]

And you are calling day_confirmed('mon21') and trying to find the column 'mon21' where it is true , you can use .to_sym on the date variable

 def day_confirmed(day)
    User.where(day.to_sym => true).count
  end

the .to_sym will get the value of date , and covert it to :mon21