rails + arel，一个更清晰的方式:

# Table name: messages
#
# sender_id:    integer
# recipient_id: integer
# content:      text

class Message < ActiveRecord::Base
  scope :by_participant, ->(user_id) do
    left  = arel_table[:sender_id].eq(user_id)
    right = arel_table[:recipient_id].eq(user_id)

    where(Arel::Nodes::Or.new(left, right))
  end
end

生产:

$ Message.by_participant(User.first.id).to_sql 
=> SELECT `messages`.* 
     FROM `messages` 
    WHERE `messages`.`sender_id` = 1 
       OR `messages`.`recipient_id` = 1

如果你想在一个列的值上使用OR操作符，你可以传递一个数组到.where, ActiveRecord将使用IN(value,other_value):

Model.where(:column => ["value", "other_value"]

输出:

SELECT `table_name`.* FROM `table_name` WHERE `table_name`.`column` IN ('value', 'other_value')

这应该在单个列上实现与OR相同的效果

如果你想使用数组作为参数，下面的代码在Rails 4中工作:

query = Order.where(uuid: uuids, id: ids)
Order.where(query.where_values.map(&:to_sql).join(" OR "))
#=> Order Load (0.7ms)  SELECT "orders".* FROM "orders" WHERE ("orders"."uuid" IN ('5459eed8350e1b472bfee48375034103', '21313213jkads', '43ujrefdk2384us') OR "orders"."id" IN (2, 3, 4))

更多信息:在Rails 4中使用数组作为参数的OR查询。

用服装

t = Post.arel_table

results = Post.where(
  t[:author].eq("Someone").
  or(t[:title].matches("%something%"))
)

结果SQL:

ree-1.8.7-2010.02 > puts Post.where(t[:author].eq("Someone").or(t[:title].matches("%something%"))).to_sql
SELECT     "posts".* FROM       "posts"  WHERE     (("posts"."author" = 'Someone' OR "posts"."title" LIKE '%something%'))

Rails最近将其添加到ActiveRecord中。它将在Rails 5中发布。已致力于掌握:

https://github.com/rails/rails/commit/9e42cf019f2417473e7dcbfcb885709fa2709f89

Post.where(column: 'something').or(Post.where(other: 'else'))

# => SELECT * FROM posts WHERE (column = 'something') OR (other = 'else)

Rails/ActiveRecord的更新版本可能原生支持此语法。它看起来类似于:

Foo.where(foo: 'bar').or.where(bar: 'bar')

如此拉请求https://github.com/rails/rails/pull/9052中所述

现在，只要坚持下面的方法就可以了:

Foo.where('foo= ? OR bar= ?', 'bar', 'bar')

更新:根据https://github.com/rails/rails/pull/16052, or特性将在Rails 5中可用

更新:特性已经合并到Rails 5分支