Arel语法（此AND此）OR（此AND此）

Question

how would I do this in Arel ( this AND this) OR ( this AND this)

Context is rails 3.0.7

Answer 1

Mike's answer was basically what you're looking for

class Model < ActiveRecord::Base
  def self.this_or_that(a1, a2, a3, a4)
    t = Model.arel_table
    q1 = t[:a].eq(a1).and(t[:b].eq(a2))
    q2 = t[:c].eq(a3).and(t[:d].eq(a4))
    where(q1.or(q2))
  end
end

some slides I put together on Arel

Answer 2

I'd put this all in a single where block. For example, here's a 'scope' based on a similar complex 'where' clause:

class Foo < ActiveRecord::Base
  def self.my_complex_where(args)
    where("(col1 = ? AND col2 = ?) OR (col3 = ? AND col4 = ?)", 
          args[:val1], args[:val2], args[:val3], args[:val4])
  end
end

Alternatively, you could do it using this notation:

class Foo < ActiveRecord::Base
  def self.my_complex_where(args)
    where("(col1 = :val1 AND col2 = :val2) OR (col3 = :val3 AND col4 = :val4)", 
          :val1 => args[:val1], 
          :val2 => args[:val2], 
          :val3 => args[:val3],
          :val4 => args[:val4])
  end
end

Answer 3

You need to drop down to more raw AREL

t = Model.arel_table
a = (t[:a].eq(nil).and(t[:b].eq(nil)))
b = (t[:a].not_eq(nil).and(t[:b].not_eq(nil)))
Model.where(a.and(b))

Answer 4

Besides the answers already given, you might also want to take a look at the gem ' squeel '

Example:

Person.where{(name =~ 'Ernie%') & (salary < 50000) | (name =~ 'Joe%') & (salary > 100000)}

Answer 5

我不知道帮助方法，但你总是可以下载到（几乎）纯SQL ：

Client.where("orders_count = ? AND locked = ?", params[:orders], false)