Rails 5 中的 OR 子句

Question

如何在 Rails 5 ActiveRecord 中获取 (A || B) && ( C || D) 查询？我试过 Post.where(a).or(Post.where(b)).where(c).or(Post.where(d))

但它产生为：(A || B) && C || D。获得所需查询的正确代码是什么？

Answer 1

Rails or() 方法没有这个复杂。首次提出时，关于该功能的讨论很长here, on Github

此方法旨在提供一种便捷的 Railsifying 查询方式，但有时事情并没有那么简单。 or() 方法本质上是从左到右读取。

在坚持“Railsy”约定时，您最好的选择是遵循以下方法之一：

Post.where("a OR b").where("c OR d")             # Example 1 - SQL with additional where()
Post.where(a: [true, !b]).where(c: [true, !d])   # Example 2 - Array comparison
Post.where("(a OR b) AND (c OR d)")              # Example 3 - SQL only

Answer 2

您是否尝试过将每个or 查询下推到Post 模型中的各个命名范围？对我来说，将它们分开会产生不同的结果。试试下面的代码，看看你是否得到了预期的结果（我手边没有 Rails 应用程序，所以我把所有东西都放在一个 Ruby 文件中）：

rails_where_or.rb

require 'active_record'
require 'rspec'

ActiveRecord::Base.establish_connection(
  adapter: 'sqlite3', database: ':memory:'
)

ActiveRecord::Schema.define do
  create_table :posts do |t|
    t.boolean :a, default: false
    t.boolean :b, default: false
    t.boolean :c, default: false
    t.boolean :d, default: false
  end
end

class Post < ActiveRecord::Base
  def self.a_or_b_and_c_or_d
    a_or_b.c_or_d
  end

  def self.a_or_b_and_c_or_d_all_chained
    where(a: true).or(where(b: true)).
      where(c: true).or(where(d: true))
  end

  def self.a_or_b
    where(a: true).or(where(b: true))
  end

  def self.c_or_d
    where(c: true).or(where(d: true))
  end
end

RSpec.describe Post do
  let!(:only_a) do
    described_class.create!(a: true)
  end
  let!(:only_b) do
    described_class.create!(b: true)
  end
  let!(:only_c) do
    described_class.create!(c: true)
  end
  let!(:only_d) do
    described_class.create!(d: true)
  end
  let!(:a_and_b) do
    described_class.create!(a: true, b: true)
  end
  let!(:a_and_c) do
    described_class.create!(a: true, c: true)
  end
  let!(:a_and_d) do
    described_class.create!(a: true, d: true)
  end
  let!(:b_and_c) do
    described_class.create!(b: true, c: true)
  end
  let!(:b_and_d) do
    described_class.create!(b: true, d: true)
  end
  let!(:c_and_d) do
    described_class.create!(c: true, d: true)
  end

  describe '.a_or_b_and_c_or_d' do
    let(:a_or_b_and_c_or_d) do
      described_class.a_or_b_and_c_or_d
    end

    it 'returns only records that match (A || B) && ( C || D )' do
      expect(a_or_b_and_c_or_d).not_to include(only_a)
      expect(a_or_b_and_c_or_d).not_to include(only_b)
      expect(a_or_b_and_c_or_d).not_to include(only_c)
      expect(a_or_b_and_c_or_d).not_to include(only_d)
      expect(a_or_b_and_c_or_d).not_to include(a_and_b)
      expect(a_or_b_and_c_or_d).not_to include(c_and_d)
      expect(a_or_b_and_c_or_d).to include(a_and_c)
      expect(a_or_b_and_c_or_d).to include(a_and_d)
      expect(a_or_b_and_c_or_d).to include(b_and_c)
      expect(a_or_b_and_c_or_d).to include(b_and_d)
    end
  end

  describe '.a_or_b_and_c_or_d_all_chained' do
    let(:a_or_b_and_c_or_d_all_chained) do
      described_class.a_or_b_and_c_or_d_all_chained
    end

    it 'returns records that match (A || B) && C || D ' do
      expect(a_or_b_and_c_or_d_all_chained).not_to include(only_a)
      expect(a_or_b_and_c_or_d_all_chained).not_to include(only_b)
      expect(a_or_b_and_c_or_d_all_chained).not_to include(only_c)
      expect(a_or_b_and_c_or_d_all_chained).not_to include(a_and_b)
      expect(a_or_b_and_c_or_d_all_chained).to include(only_d)
      expect(a_or_b_and_c_or_d_all_chained).to include(c_and_d)
      expect(a_or_b_and_c_or_d_all_chained).to include(a_and_c)
      expect(a_or_b_and_c_or_d_all_chained).to include(a_and_d)
      expect(a_or_b_and_c_or_d_all_chained).to include(b_and_c)
      expect(a_or_b_and_c_or_d_all_chained).to include(b_and_d)
    end
  end
end