So basically I want something like this:
#network = Network.where(:id => current_user.network_ids).first
#posts = Post.where(:user.network.first => #network).order("created_at DESC")
But it basically doesn't recognize the column :user in the second line as the real column is user_id. I even tried:
#posts = Post.where('User.find(user_id).network.first =?',network )
with no luck
any ideas on how I could approach this.
model:
class User
has_and_belongs_to_many :network
has_many :posts
end
class Network
has_and_belongs_to_many :user
end
class Post
belongs_to :user
end
I basically want to filter the posts according to the network of the current user
So I simply solved the problem by using:
#posts = Post.where('user_id = ?', #network.user_ids)
As i can see, you have posts which belongs to a user and then user has many networks therefore your query should be
#posts = Post.where(:user.networks.first => #network).order("created_at DESC")
what your are calling is
:user.network.first
which states user has has_one relationship with network
I'm trying to create some kind of activity feed, and I'm having trouble getting the values I need to.
I have a controller with this action
def show
#user = User.find(params[:id])
#ideas = Idea.find(#user)
#lists = List.find(#user)
#li_array = (#lists + #ideas).sort{|a,b| -(a.created_at <=> b.created_at)}
end
I'm new to rails, and I'm trying to put together an array of values from the users of both ideas and lists. But I figured out that I can't do what I'm doing now because it will only pass the current user's id to match an id for Idea/List, but what I need to do is find the user's id column and search through based on #user.
I need to get all values from the users, what is the best method?
models
user.rb
has_many :lists
has_many :ideas, :through => :lists
list.rb
has_many :ideas
belongs_to :user
idea.rb
belongs_to :list
belongs_to :user
Thanks
You can simply do:
#user = User.find(params[:id])
#ideas = #user.ideas
#lists = #user.lists
In Rails 3.2 I have been looking for a way to traverse the associations of an object within the before_add callback.
So basically my use case is:
class User < ActiveRecord::Base
has_and_belongs_to_many :meetings
end
class Meeting < ActiveRecord::Base
has_and_belongs_to_many :users
has_many :comments, :before_add => :set_owner_id
end
class Comment < ActiveRecord::Base
belongs_to :meeting
end
def set_owner_id(child)
child.owner_id = <<<THE USER ID for #user >>>
end
and I am creating a comment within the context of a user:
#user.meetings.first.comments.create
How do I traverse the associations from within the before_add callback to discover the id of #user? I want to set this at model level. I have been looking at proxy_association, but I may be missing something. Any ideas?
You should probably create the comment in the context of the meeting, no? Either way, you should handle this in the controller since you'll have no access to #user in your model.
#comment = Meeting.find(id).comments.create(owner_id: #user, ... )
But if you insist on your way, do this:
#comment = #user.meetings.first.comments.create(owner_id: #user.id)
I'm not exactly sure what my problem is, so this question may require some more clarification, but here's what seems to be most relevant:
I have a has_many :through and the join model has some fields that aren't foreign keys. When I build the models up and try to save I get a validation error on the non-foreign key fields from the join model.
My files look like:
Person.rb
has_many :wedding_assignments, :dependent => :destroy
has_many :weddings, :through=>:wedding_assignments
accepts_nested_attributes_for :weddings
accepts_nested_attributes_for :wedding_assignments
Wedding.rb
has_many :wedding_assignments, :dependent => :destroy
has_many :people, :through=>:wedding_assignments
accepts_nested_attributes_for :people
accepts_nested_attributes_for :wedding_assignments
WeddingAssignment.rb
belongs_to :person
belongs_to :wedding
validates_presence_of :role, :person, :wedding
(role is a string)
people_controller.rb
def new
#person = Person.new
1.times do
wedding = #person.weddings.build
1.times do
assignment = wedding.wedding_assignments.build
assignment.person = #person
assignment.wedding = wedding
end
end
end
def create
#person = Person.new(params[:person])
#person.weddings.each do |wedding|
wedding.wedding_assignments.each do |assignment|
assignment.person = #person #i don't think I should need to set person and wedding manually, but I get a validation error if I don't
assignment.wedding = wedding
end
end
end
the params that come back look like:
{"first_name"=>"", "last_name"=>"", "weddings_attributes"=>{"0"=>{"wedding_assignments_attributes"=>{"0"=>{"role"=>"Bride's Maid", "budget"=>""}}, "date"=>"", "ceremony_notes"=>""}}}
And the exact error is:
ActiveRecord::RecordInvalid in PeopleController#create
Validation failed: Role can't be blank
Which is clearly not correct, since you can see it in params[]
What am I doing wrong?
This is rails 3.0.0
Right, this is a bit of a guess, so apologies if I wind up wasting your time here...
It looks to me like in your create method, you're creating the 'wedding' relationship (which is only a 'pretend' relationship really, has it's using :through => :wedding_assignments), and then returning this. You're then asking rails to re-create these objects in your call to Person.new. My guess is that rails is getting confused by trying to create an object at the far side of a has_many :through without the intermediate object being present.
I would be tempted to restructure this a little (untested code!):
def new
#person = Person.new
#wedding = Wedding.new
#wedding_assignment = WeddingAssignment.new
end
def create
#person = Person.new(params[:person])
#wedding = Wedding.new(params[:person])
#assignment = WeddingAssignment.new(params[:wedding_assignment].merge({:person => #person}))
end
I've got a feeling this'll work until the last line. I suspect to get that to work you might need to use transactions:
def create
#person = Person.new(params[:person])
#wedding = Wedding.new(params[:person])
ActiveRecord::Base.transaction do
if #person.valid? && #wedding.valid?
[#person,#wedding].each.save!
#assignment = WeddingAssignment.new(params[:wedding_assignment].merge({:person => #person}))
#assignment.save!
end
end
end
This ought to ensure that everything is created in the right order and IDs are available at the right times etc. Unfortunately though, it's a bit more complicated than your example, and does mean that you'll struggle to support multiple weddings.
Hope this helps, and doesn't wind up being a blind alley.
Try changing "Person.new" to "Person.create", maybe creating the record in the db right away will help with the associations.
I'm using Rails' accepts_nested_attributes_for method with great success, but how can I have it not create new records if a record already exists?
By way of example:
Say I've got three models, Team, Membership, and Player, and each team has_many players through memberships, and players can belong to many teams. The Team model might then accept nested attributes for players, but that means that each player submitted through the combined team+player(s) form will be created as a new player record.
How should I go about doing things if I want to only create a new player record this way if there isn't already a player with the same name? If there is a player with the same name, no new player records should be created, but instead the correct player should be found and associated with the new team record.
When you define a hook for autosave associations, the normal code path is skipped and your method is called instead. Thus, you can do this:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
else
self.author.save!
end
end
end
This code is untested, but it should be pretty much what you need.
Don't think of it as adding players to teams, think of it as adding memberships to teams. The form doesn't work with the players directly. The Membership model can have a player_name virtual attribute. Behind the scenes this can either look up a player or create one.
class Membership < ActiveRecord::Base
def player_name
player && player.name
end
def player_name=(name)
self.player = Player.find_or_create_by_name(name) unless name.blank?
end
end
And then just add a player_name text field to any Membership form builder.
<%= f.text_field :player_name %>
This way it is not specific to accepts_nested_attributes_for and can be used in any membership form.
Note: With this technique the Player model is created before validation happens. If you don't want this effect then store the player in an instance variable and then save it in a before_save callback.
A before_validation hook is a good choice: it's a standard mechanism resulting in simpler code than overriding the more obscure autosave_associated_records_for_*.
class Quux < ActiveRecord::Base
has_and_belongs_to_many :foos
accepts_nested_attributes_for :foos, reject_if: ->(object){ object[:value].blank? }
before_validation :find_foos
def find_foos
self.foos = self.foos.map do |object|
Foo.where(value: object.value).first_or_initialize
end
end
end
When using :accepts_nested_attributes_for, submitting the id of an existing record will cause ActiveRecord to update the existing record instead of creating a new record. I'm not sure what your markup is like, but try something roughly like this:
<%= text_field_tag "team[player][name]", current_player.name %>
<%= hidden_field_tag "team[player][id]", current_player.id if current_player %>
The Player name will be updated if the id is supplied, but created otherwise.
The approach of defining autosave_associated_record_for_ method is very interesting. I'll certainly use that! However, consider this simpler solution as well.
Just to round things out in terms of the question (refers to find_or_create), the if block in Francois' answer could be rephrased as:
self.author = Author.find_or_create_by_name(author.name) unless author.name.blank?
self.author.save!
This works great if you have a has_one or belongs_to relationship. But fell short with a has_many or has_many through.
I have a tagging system that utilizes a has_many :through relationship. Neither of the solutions here got me where I needed to go so I came up with a solution that may help others. This has been tested on Rails 3.2.
Setup
Here are a basic version of my Models:
Location Object:
class Location < ActiveRecord::Base
has_many :city_taggables, :as => :city_taggable, :dependent => :destroy
has_many :city_tags, :through => :city_taggables
accepts_nested_attributes_for :city_tags, :reject_if => :all_blank, allow_destroy: true
end
Tag Objects
class CityTaggable < ActiveRecord::Base
belongs_to :city_tag
belongs_to :city_taggable, :polymorphic => true
end
class CityTag < ActiveRecord::Base
has_many :city_taggables, :dependent => :destroy
has_many :ads, :through => :city_taggables
end
Solution
I did indeed override the autosave_associated_recored_for method as follows:
class Location < ActiveRecord::Base
private
def autosave_associated_records_for_city_tags
tags =[]
#For Each Tag
city_tags.each do |tag|
#Destroy Tag if set to _destroy
if tag._destroy
#remove tag from object don't destroy the tag
self.city_tags.delete(tag)
next
end
#Check if the tag we are saving is new (no ID passed)
if tag.new_record?
#Find existing tag or use new tag if not found
tag = CityTag.find_by_label(tag.label) || CityTag.create(label: tag.label)
else
#If tag being saved has an ID then it exists we want to see if the label has changed
#We find the record and compare explicitly, this saves us when we are removing tags.
existing = CityTag.find_by_id(tag.id)
if existing
#Tag labels are different so we want to find or create a new tag (rather than updating the exiting tag label)
if tag.label != existing.label
self.city_tags.delete(tag)
tag = CityTag.find_by_label(tag.label) || CityTag.create(label: tag.label)
end
else
#Looks like we are removing the tag and need to delete it from this object
self.city_tags.delete(tag)
next
end
end
tags << tag
end
#Iterate through tags and add to my Location unless they are already associated.
tags.each do |tag|
unless tag.in? self.city_tags
self.city_tags << tag
end
end
end
The above implementation saves, deletes and changes tags the way I needed when using fields_for in a nested form. I'm open to feedback if there are ways to simplify. It is important to point out that I am explicitly changing tags when the label changes rather than updating the tag label.
Answer by #François Beausoleil is awesome and solved a big problem. Great to learn about the concept of autosave_associated_record_for.
However, I found one corner case in this implementation. In case of update of existing post's author(A1), if a new author name(A2) is passed, it will end up changing the original(A1) author's name.
p = Post.first
p.author #<Author id: 1, name: 'JK Rowling'>
# now edit is triggered, and new author(non existing) is passed(e.g: Cal Newport).
p.author #<Author id: 1, name: 'Cal Newport'>
Oringinal code:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
else
self.author.save!
end
end
end
It is because, in case of edit, self.author for post will already be an author with id:1, it will go in else, block and will update that author instead of creating new one.
I changed the code(elsif condition) to mitigate this issue:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
elsif author && author.persisted? && author.changed?
# New condition: if author is already allocated to post, but is changed, create a new author.
self.author = Author.new(name: author.name)
else
# else create a new author
self.author.save!
end
end
end
#dustin-m's answer was instrumental for me - I am doing something custom with a has_many :through relationship. I have a Topic which has one Trend, which has many children (recursive).
ActiveRecord does not like it when I configure this as a standard has_many :searches, through: trend, source: :children relationship. It retrieves topic.trend and topic.searches but won't do topic.searches.create(name: foo).
So I used the above to construct a custom autosave and am achieving the correct result with accepts_nested_attributes_for :searches, allow_destroy: true
def autosave_associated_records_for_searches
searches.each do | s |
if s._destroy
self.trend.children.delete(s)
elsif s.new_record?
self.trend.children << s
else
s.save
end
end
end