I have a simple has_many association, and I want to change an attribute from public to private the associated object. What's the best way to do this:
class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
end
user = User.first #=> #<User...>
user.posts.count #=> 100
# something like this:
user.posts.bulk_update_attribute("privacy", "private") #=> 1 DB call
I believe you are looking for update_all.
In your example, you'd rewrite it to be something like
Post.update_all("privacy = 'private'", ["user_id = ?", user.id])
Or as #jenjenut233 points out
user.posts.update_all("privacy = 'private'")
Related
Let me show an example:
I have 2 models:
class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
scope :created_in, ->(start_date, end_date) { where(created_at: start_date..end_date) }
end
What I want is to get users that created post during a specific period:
users = User.includes(:posts).joins(:posts).merge(Post.created_in(start_date, end_date))
Is it somehow possible to cache posts that are in the where clause? So after I do
users.first.posts
it will show me exactly those posts that match the condition without producing any additional queries.
No, I don't think this is possible. Depending on the context, what you can do is to do a lookup table which you memoize / cache. Something like
User.all.each do |user|
posts = posts_by_user_id[user.id]
end
def posts_by_user_id
#_posts_by_user_id ||= posts.group_by(&:user_id)
end
def posts
Post.created_in(start_date, end_date)
end
I have the following models:
class User < ActiveRecord::Base
has_many :survey_takings
end
class SurveyTaking < ActiveRecord::Base
belongs_to :survey
def self.surveys_taken # must return surveys, not survey_takings
where(:state => 'completed').map(&:survey)
end
def self.last_survey_taken
surveys_taken.maximum(:position) # that's Survey#position
end
end
The goal is to be able to call #user.survey_takings.last_survey_taken from a controller. (That's contrived, but go with it; the general goal is to be able to call class methods on #user.survey_takings that can use relations on the associated surveys.)
In its current form, this code won't work; surveys_taken collapses the ActiveRelation into an array when I call .map(&:survey). Is there some way to instead return a relation for all the joined surveys? I can't just do this:
def self.surveys_taken
Survey.join(:survey_takings).where("survey_takings.state = 'completed'")
end
because #user.survey_takings.surveys_taken would join all the completed survey_takings, not just the completed survey_takings for #user.
I guess what I want is the equivalent of
class User < ActiveRecord::Base
has_many :survey_takings
has_many :surveys_taken, :through => :survey_takings, :source => :surveys
end
but I can't access that surveys_taken association from SurveyTaking.last_survey_taken.
If I'm understanding correctly you want to find completed surveys by a certain user? If so you can do:
Survey.join(:survey_takings).where("survey_takings.state = 'completed'", :user => #user)
Also it looks like instead of:
def self.surveys_taken
where(:state => 'completed').map(&:survey)
end
You may want to use scopes:
scope :surveys_taken, where(:state => 'completed')
I think what I'm looking for is this:
class SurveyTaking < ActiveRecord::Base
def self.surveys_taken
Survey.joins(:survey_takings).where("survey_takings.state = 'completed'").merge(self.scoped)
end
end
This way, SurveyTaking.surveys_taken returns surveys taken by anyone, but #user.survey_takings.surveys_taken returns surveys taken by #user. The key is merge(self.scoped).
Waiting for further comments before I accept..
I'm trying to query across models with the following setup
Class Scorecard < AR::Base
default_scope where(:archived => false)
belongs_to :user
has_many :scorecard_metrics
end
Class ScorecardMetric < AR::Base
belongs_to :scorecard
end
Class User < AR::Base
has_many :scorecards
end
I am trying to query from scorecard metrics with a named scope that joins scorecard and I want it to include the default scope for scorecard, my current implementation (which works) looks like this
# on ScorecardMetric
scope :for_user, lambda {
|user| joins(:scorecard).
where("scorecards.user_id = ? and scorecards.archived = ?", user.id, false)
}
This just seems messy to me, is there any way to join and include the default scope of the joined association?
Looks like I found the answer I was looking for, I just did this
scope :for_user, lambda { |user| joins(:scorecard).where('scorecards.user_id = ?', user.id) & Scorecard.scoped }
which is much nicer without the duplicated logic
I'd like to extract out logic from the controllers to somewhere that it can be more DRY. What's the best way of handling something like the following in Rails?
For instance, as opposed to having the query in the controllers, I could place it in the model:
class SmoothieBlender < ActiveRecord::Base
belongs_to :user
def self.get_blenders_for_user(user)
self.where(["user_id = ?", user.id])
end
end
Or would it be better to create a module as a service layer and include that in each model that uses it?
module BlenderUser
def get_blenders_for_user(user)
SmoothieBlender.where(["user_id = ?", user.id])
end
end
class SmoothieBlender < ActiveRecord::Base
include BlenderUser
belongs_to :user
end
class User < ActiveRecord::Base
include BlenderUser
has_many :smoothie_blenders
end
Or just make it a full blown service class that's accessible from the User and Blender controller? Where would you put this class?
class BlenderService
def self.get_blenders_for_user(user)
SmoothieBlender.where(["user_id = ?", user.id])
end
end
I'm new to Ruby and Rails, so if this is a silly question/syntax is incorrect, forgive me. Thanks in advance!
I'd create a named_scope (I think it's just scope in Rails 3)
class SmoothieBlender < ActiveRecord::Base
belongs_to :user
scope :for_user, lambda { |user_id|
where("user_id = ?", user_id)
}
end
This way you can call
SmoothieBlender.for_user(user.id)
I was wondering if it was possible to use the find method to order the results based on a class's has_many relationship with another class. e.g.
# has the columns id, name
class Dog < ActiveRecord::Base
has_many :dog_tags
end
# has the columns id, color, dog_id
class DogTags < ActiveRecord::Base
belongs_to :dog
end
and I would like to do something like this:
#result = DogTag.find(:all, :order => dog.name)
thank you.
In Rails 4 it should be done this way:
#result = DogTag.joins(:dog).order('dogs.name')
or with scope:
class DogTags < ActiveRecord::Base
belongs_to :dog
scope :ordered_by_dog_name, -> { joins(:dog).order('dogs.name') }
end
#result = DogTags.ordered_by_dog_name
The second is easier to mock in tests as controller doesn't have to know about model details.
You need to join the related table to the request.
#result = DogTag.find(:all, :joins => :dog, :order => 'dogs.name')
Note that dogs is plural in the :order statement.