Ruby on rails 不确定如何使用Mongoid中的标志建模多对多关系
我有两个实体,项目和用户。它们在Rails中使用Mongoid和两个文档实例(User和Project)进行建模 在这个系统中,一个用户可以创建一个项目,但是许多用户可以跟踪许多项目。例如,作为用户\u id 1,我创建了项目\u id 1。但是用户id 10、11、40和60都遵循项目id 1。我需要表示用户和项目之间的多对多关系,并将特定的用户id表示为项目的创建者,以分配给他编辑权限 实际上,当用户登录时,他需要能够看到他正在关注的所有项目,包括他创建的任何项目,以及其他用户创建的其他项目。他的特殊创造者身份根本不会影响这份名单。当用户查看特定项目时,他需要能够查看项目的所有用户,如果他是创建者,他可以添加新的关注者并删除现有的关注者 在RDBMS中,我将用表Ruby on rails 不确定如何使用Mongoid中的标志建模多对多关系,ruby-on-rails,mongodb,mongoid,Ruby On Rails,Mongodb,Mongoid,我有两个实体,项目和用户。它们在Rails中使用Mongoid和两个文档实例(User和Project)进行建模 在这个系统中,一个用户可以创建一个项目,但是许多用户可以跟踪许多项目。例如,作为用户\u id 1,我创建了项目\u id 1。但是用户id 10、11、40和60都遵循项目id 1。我需要表示用户和项目之间的多对多关系,并将特定的用户id表示为项目的创建者,以分配给他编辑权限 实际上,当用户登录时,他需要能够看到他正在关注的所有项目,包括他创建的任何项目,以及其他用户创建的其他项目
users
、projects
和users\u projects
join表来表示这一点,该表的标志为is\u creator
。这将很容易让我选择用户可以看到哪些项目,哪些用户是项目的追随者,包括哪些用户是项目的创建者
Mongoid支持多对多关系,但与RDBMS不同,我无法在关系上设置标志。相反,我想我将在项目
文档中添加一个创建者
字段,该字段将包含一个指向用户文档上\u id
字段的链接
用户->项目关系可能如下所示
class User
has_and_belongs_to_many :projects
end
class Project
has_and_belongs_to_many: users
end
但是我不知道如何映射creator->created\u projects之间的关系。我相信我可以在Project
中引用用户创建者,比如属于:creator,:class\u name=>“user”
,但我不确定如何设置另一方
如何在Mongoid中对这些关系进行最佳建模?创建一个嵌入式文档,其中包含所有关注者及其用户id和用户名,这样您就不必查询关注者的用户名 好处:
- 没有一个查询可以查找项目的跟随者
- 只有一个查询可以查找用户的后续项目
- 如果一个用户更改了他的名字,你必须更新他的所有“followships”,但更新频率如何 与查找后续项目的频率相比,您是否更改了名称;)
- 如果每个项目有数千名追随者,则可能达到16mb的文档限制
class User
# projects this user owns
has_many :projects
def followed_projects
Project.where('followers.user_id' => self.id)
end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {'followers.user_id' => self.id})
end
end
class Project
# creator
belongs_to :user
embeds_many :followers
# add an index because we're going to query on this
index 'followers.user_id'
# adds a follower
# maybe you want to add some validations, preventing duplicate followers
def add_follower!(user_obj)
self.followers.create({
:user => user_obj,
:username => user_obj.username
})
end
def remove_follower!(user_obj)
self.followers.destroy_all(:conditions => {:user_id => user_obj.id})
end
end
class Follower
include Mongoid::Document
include Mongoid::Timestamps
embedded_in :project
# reference to the real user
belongs_to :user
# cache the username
field :username, :type => String
end
class User
# projects this user owns
has_many :projects
has_many :followed_projects,
:class_name => 'Project',
:foreign_key => :follower_ids
# Uncomment if the relation does not work
#def followed_projects
# Project.where(:follower_ids => self.id)
#end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {:follower_ids => self.id})
end
end
class Project
# creator
belongs_to :user
field :follower_ids, :type => Array
# adds a follower
def add_follower!(user_obj)
# adds a user uniquely to the follower_ids array
self.add_to_set(:follower_ids, user_obj.id)
end
def remove_follower!(user_obj)
# remove the user
self.pull(:follower_ids, user_obj.id)
end
end
project.rb
class User
# projects this user owns
has_many :projects
def followed_projects
Project.where('followers.user_id' => self.id)
end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {'followers.user_id' => self.id})
end
end
class Project
# creator
belongs_to :user
embeds_many :followers
# add an index because we're going to query on this
index 'followers.user_id'
# adds a follower
# maybe you want to add some validations, preventing duplicate followers
def add_follower!(user_obj)
self.followers.create({
:user => user_obj,
:username => user_obj.username
})
end
def remove_follower!(user_obj)
self.followers.destroy_all(:conditions => {:user_id => user_obj.id})
end
end
class Follower
include Mongoid::Document
include Mongoid::Timestamps
embedded_in :project
# reference to the real user
belongs_to :user
# cache the username
field :username, :type => String
end
class User
# projects this user owns
has_many :projects
has_many :followed_projects,
:class_name => 'Project',
:foreign_key => :follower_ids
# Uncomment if the relation does not work
#def followed_projects
# Project.where(:follower_ids => self.id)
#end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {:follower_ids => self.id})
end
end
class Project
# creator
belongs_to :user
field :follower_ids, :type => Array
# adds a follower
def add_follower!(user_obj)
# adds a user uniquely to the follower_ids array
self.add_to_set(:follower_ids, user_obj.id)
end
def remove_follower!(user_obj)
# remove the user
self.pull(:follower_ids, user_obj.id)
end
end
follower.rb
class User
# projects this user owns
has_many :projects
def followed_projects
Project.where('followers.user_id' => self.id)
end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {'followers.user_id' => self.id})
end
end
class Project
# creator
belongs_to :user
embeds_many :followers
# add an index because we're going to query on this
index 'followers.user_id'
# adds a follower
# maybe you want to add some validations, preventing duplicate followers
def add_follower!(user_obj)
self.followers.create({
:user => user_obj,
:username => user_obj.username
})
end
def remove_follower!(user_obj)
self.followers.destroy_all(:conditions => {:user_id => user_obj.id})
end
end
class Follower
include Mongoid::Document
include Mongoid::Timestamps
embedded_in :project
# reference to the real user
belongs_to :user
# cache the username
field :username, :type => String
end
class User
# projects this user owns
has_many :projects
has_many :followed_projects,
:class_name => 'Project',
:foreign_key => :follower_ids
# Uncomment if the relation does not work
#def followed_projects
# Project.where(:follower_ids => self.id)
#end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {:follower_ids => self.id})
end
end
class Project
# creator
belongs_to :user
field :follower_ids, :type => Array
# adds a follower
def add_follower!(user_obj)
# adds a user uniquely to the follower_ids array
self.add_to_set(:follower_ids, user_obj.id)
end
def remove_follower!(user_obj)
# remove the user
self.pull(:follower_ids, user_obj.id)
end
end
如何使用它:
@project = Project.first
@some_user = User.last
@project.add_follower!(@some_user)
@some_user.followed_projects
@some_user.related_projects
@project.followers.each do |c_follower|
puts "I'm #{c_follower.username} and I'm following this project!"
end
@all_follower_user_ids = @project.followers.map{|c| c.user_id}
# find a specific follower by user_id
@some_follower = @project.followers.where(:user_id => 1234)
# find a specific follower by username
@some_follower = @project.followers.where(:username => 'The Dude')
@project.remove_follower!(@some_user)
@project = Project.first
@some_user = User.last
@project.add_follower!(@some_user)
@some_user.followed_projects
@some_user.related_projects
# create hash like @ids_to_user[user_id] = user
@ids_to_users = User.find(@project.follower_ids).inject({}) {|hsh, c_user| hsh[c_user.id] = c_user; hsh}
@project.followers.each do |c_follower|
puts "I'm #{@ids_to_users[c_follower].username} and I'm following this project!"
end
@project.remove_follower!(@some_user)
PS:如果您想要一个更简单的解决方案,您可以在项目中嵌入一个ObjectID数组(用户ID),并使用原子更新
$addToSet
和$pullAll
来添加/删除跟随者。但是您需要一个额外的查询,如User.where(:User\u id.in=>@project.follower\u id)
(假设数组名为follower\u id
),以获取所有用户及其姓名;) 第二个版本使用更少的空间,但需要额外的查询来获取用户名等用户详细信息。一个对象ID有12个字节,最大文档大小为16mb,因此阵列可以容纳约130万个用户ID(理论上!)
给你:
user.rb
class User
# projects this user owns
has_many :projects
def followed_projects
Project.where('followers.user_id' => self.id)
end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {'followers.user_id' => self.id})
end
end
class Project
# creator
belongs_to :user
embeds_many :followers
# add an index because we're going to query on this
index 'followers.user_id'
# adds a follower
# maybe you want to add some validations, preventing duplicate followers
def add_follower!(user_obj)
self.followers.create({
:user => user_obj,
:username => user_obj.username
})
end
def remove_follower!(user_obj)
self.followers.destroy_all(:conditions => {:user_id => user_obj.id})
end
end
class Follower
include Mongoid::Document
include Mongoid::Timestamps
embedded_in :project
# reference to the real user
belongs_to :user
# cache the username
field :username, :type => String
end
class User
# projects this user owns
has_many :projects
has_many :followed_projects,
:class_name => 'Project',
:foreign_key => :follower_ids
# Uncomment if the relation does not work
#def followed_projects
# Project.where(:follower_ids => self.id)
#end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {:follower_ids => self.id})
end
end
class Project
# creator
belongs_to :user
field :follower_ids, :type => Array
# adds a follower
def add_follower!(user_obj)
# adds a user uniquely to the follower_ids array
self.add_to_set(:follower_ids, user_obj.id)
end
def remove_follower!(user_obj)
# remove the user
self.pull(:follower_ids, user_obj.id)
end
end
project.rb
class User
# projects this user owns
has_many :projects
def followed_projects
Project.where('followers.user_id' => self.id)
end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {'followers.user_id' => self.id})
end
end
class Project
# creator
belongs_to :user
embeds_many :followers
# add an index because we're going to query on this
index 'followers.user_id'
# adds a follower
# maybe you want to add some validations, preventing duplicate followers
def add_follower!(user_obj)
self.followers.create({
:user => user_obj,
:username => user_obj.username
})
end
def remove_follower!(user_obj)
self.followers.destroy_all(:conditions => {:user_id => user_obj.id})
end
end
class Follower
include Mongoid::Document
include Mongoid::Timestamps
embedded_in :project
# reference to the real user
belongs_to :user
# cache the username
field :username, :type => String
end
class User
# projects this user owns
has_many :projects
has_many :followed_projects,
:class_name => 'Project',
:foreign_key => :follower_ids
# Uncomment if the relation does not work
#def followed_projects
# Project.where(:follower_ids => self.id)
#end
# get projects that this user has created and projects he is following
def related_projects
Project.any_of({:user_id => self.id}, {:follower_ids => self.id})
end
end
class Project
# creator
belongs_to :user
field :follower_ids, :type => Array
# adds a follower
def add_follower!(user_obj)
# adds a user uniquely to the follower_ids array
self.add_to_set(:follower_ids, user_obj.id)
end
def remove_follower!(user_obj)
# remove the user
self.pull(:follower_ids, user_obj.id)
end
end
如何使用它:
@project = Project.first
@some_user = User.last
@project.add_follower!(@some_user)
@some_user.followed_projects
@some_user.related_projects
@project.followers.each do |c_follower|
puts "I'm #{c_follower.username} and I'm following this project!"
end
@all_follower_user_ids = @project.followers.map{|c| c.user_id}
# find a specific follower by user_id
@some_follower = @project.followers.where(:user_id => 1234)
# find a specific follower by username
@some_follower = @project.followers.where(:username => 'The Dude')
@project.remove_follower!(@some_user)
@project = Project.first
@some_user = User.last
@project.add_follower!(@some_user)
@some_user.followed_projects
@some_user.related_projects
# create hash like @ids_to_user[user_id] = user
@ids_to_users = User.find(@project.follower_ids).inject({}) {|hsh, c_user| hsh[c_user.id] = c_user; hsh}
@project.followers.each do |c_follower|
puts "I'm #{@ids_to_users[c_follower].username} and I'm following this project!"
end
@project.remove_follower!(@some_user)
非常感谢。这正是我想要的。问题是,我已经尝试使用您的替代建议来实现这一点,即在项目文档中存储用户id对象,但在定义项目和用户之间的关系时遇到了一个难题。你介意也贴一个解决方案的例子吗?