我正在尝试使用 Ohm 在 Redis 中创建多对多关系。例如,我将 Book 和 Author 模型定义如下:
class Book < Ohm::Model
attribute :title
set :authors, Author
end
class Author < Ohm::Model
attribute :last_name
attribute :first_name
set :books, Book
end
我希望能够做的是利用 Ohm 的索引功能来进行查找,例如:
require 'test_helper'
class ManyToManyRelationshipTest < ActiveSupport::TestCase
setup do
@dave_thomas = FactoryGirl.build(:dave_thomas)
@andy_hunt = FactoryGirl.build(:andy_hunt)
@chad_fowler = FactoryGirl.build(:chad_fowler)
@pick_axe = FactoryGirl.build(:pick_axe)
@pick_axe.authors << @dave_thomas
@pick_axe.authors << @andy_hunt
@pick_axe.authors << @chad_fowler
@thinking_and_learning = FactoryGirl.build(:pragmatic_thinking_and_learning)
@thinking_and_learning.authors << @andy_hunt
end
test "find a Book by Author" do
assert Book.find(:author_id => @andy_hunt.id).include?(@pick_axe)
assert Book.find(:author_id => @andy_hunt.id).include?(@thinking_and_learning)
end
test "find Authors by Book" do
assert Author.find(:book_id => @pick_axe.id).include?(@dave_thomas)
assert Author.find(:book_id => @pick_axe.id).include?(@andy_hunt)
assert Author.find(:book_id => @pick_axe.id).include?(@chad_fowler)
end
end
使用上面的代码,我得到以下异常: Ohm::Model::IndexNotFound:索引:未找到 author_id。 (当试图找到给定作者的书籍时)
我已尝试按照此处所述构建自定义索引:http://ohm.keyvalue.org/examples/tagging.html ,这里:http://pinoyrb.org/ruby/ohm-inside-tricks
不幸的是,索引似乎是在首次创建模型时构建的,这意味着 Set 是空的(因为,如果我理解正确的话,在为模型分配 ID 之前,Sets 在 Ohm 中不可用)。
非常感谢任何帮助或建议!
最佳答案
这种情况下的解决方案不太自动化:
require "ohm"
class Book < Ohm::Model
attr_accessor :authors
attribute :title
index :authors
end
class Author < Ohm::Model
attribute :name
end
###
require "test/unit"
class BooksTest < Test::Unit::TestCase
def test_books_by_author
dave = Author.create(name: "Dave")
andy = Author.create(name: "Andy")
dhh = Author.create(name: "DHH")
pickaxe = Book.create(title: "Pickaxe", authors: [dave.id, andy.id])
assert_equal pickaxe, Book.find(authors: dave.id).first
assert_equal pickaxe, Book.find(authors: andy.id).first
assert_equal nil, Book.find(authors: dhh.id).first
end
end
有道理吗?
关于ruby - 与 Ruby、Redis 和 Ohm 的多对多关系,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/7967004/