Problem
class Match
has_many :items
end
class Item
belongs_to :match
validates :match, presence: true
end
class ItemBuilder
def self.build
5.times.map { |_| Item.new }
end
end
class MatchBuilder
def self.build
Match.new(items: ItemBuilder.build)
end
end
match = MatchBuilder.build
match.save # Validation fails because Item#match isn't set!
It seems to me that rails should set the Item#match association when assigning Match#items, but this is not the case.
In reality, the ItemBuilder builds Items from information from an API. I'd prefer it not to have knowledge of where those Items are going to be put, so I can't pass the match into ItemBuilder.
I'd also prefer to not have the Matchbuilder aware of the internals of the Items returned from ItemBuilder, so I can't do
class MatchBuilder
def self.build
items = ItemBuilder.build
match = Match.new(items: items)
items.each do |item|
item.match = match
end
end
end
Is there any way of getting around this, without explicitly setting Item#match?
Possible Solutions
Remove the validation, and leave the database to do the not null validation
Assign Item#match in a before_validation filter
I'd do something like this:
match = Match.new
5.times { match.items.build }
match.save
Not sure if autosave: true is needed for items association in this case.
Related
TL;DR
What is the best way to create join table entries based on a form with the attributes of a association, like a bar code or a plate number?
Detailed explanation
In this system that records movements of items between storage places, there is a has_many_and_belongs_to_many relationship between storage_movements and storage_items because items can be moved multiple times and multiple items can be moved at once.
These items are previously created and are identified by a plate number that is physically attached to the item and recorded on its creation on the application.
The problem is that I need to create storage_movements with a form where the user inputs only the plate number of the storage_item that is being moved but I cant figure it out a way to easily do this.
I have been hitting my head against this wall for some time and the only solution that I can think of is creating nested fields on the new storage_movements form for the storage_items and use specific code on the model to create, update and delete these storage_movements by explicitly querying these plate numbers and manipulating the join table entries for these actions.
Is this the correct way of handling the problem? The main issue with this solution is that I can't seem to display validation errors on the specific plates number that are wrong (I'm using simple_forms) because I don't have storage_item objects to add errors.
Below there is a snipped of the code for the form that I'm currently using. Any help is welcome :D
# views/storage_movements/_form.html.erb
<%= simple_form_for #storage_movement do |movement_form| %>
#Other form inputs
<%= movement_form.simple_fields_for :storage_items do |item_form| %>
<%= item_form.input :plate, label: "Plate number" %>
<% end %>
<% end %>
# models/storage_movement.rb
class StorageMovement < ActiveRecord::Base
has_many_and_belongs_to_many :storage_items, inverse_of: :storage_movements, validate: true
accepts_nested_attributes_for :storage_items, allow_destroy: true
... several callbacks and validations ...
end
# models/storage_item.rb
class StorageItem < ActiveRecord::Base
has_many_and_belongs_to_many :storage_movements, inverse_of: :storage_items
... more callbacks and validations ...
end
The controllers were the default generated ones.
This was my solution, it really "feels" wrong and the validations also are not shown like I want it to... But it was what I could come up with... Hopefully it helps someone.
I created the create_from_plates and update_from_plates methods on the model to handle the create and update and updated the actions of the controller to use them.
Note: had to switch to a has_many through association due to callback necessities.
# models/storage_movement.rb
class StorageMovement < ActiveRecord::Base
has_many :movements_items, dependent: :destroy, inverse_of: :storage_movement
has_many :storage_items, through: :movements_items, inverse_of: :allocations, validate: true
accepts_nested_attributes_for :storage_items, allow_destroy: true
validate :check_plates
def StorageMovement::create_from_plates mov_attributes
attributes = mov_attributes.to_h
items_attributes = attributes.delete "items_attributes"
unless items_attributes.nil?
item_plates = items_attributes.collect {|k, h| h["plate"]}
items = StorageItem.where, plate: item_plates
end
if not items_attributes.nil? and item_plates.length == items.count
new_allocation = Allocation.new attributes
movements_items.each {|i| new_allocation.items << i}
return new_allocation
else
Allocation.new mov_attributes
end
end
def update_from_plates mov_attributes
attributes = mov_attributes.to_h
items_attributes = attributes.delete "items_attributes"
if items_attributes.nil?
self.update mov_attributes
else
transaction do
unless items_attributes.nil?
items_attributes.each do |k, item_attributes|
item = StorageItem.find_by_plate(item_attributes["plate"])
if item.nil?
self.errors.add :base, "The plate #{item_attributes["plate"]} was not found"
raise ActiveRecord::Rollback
elsif item_attributes["_destroy"] == "1" or item_attributes["_destroy"] == "true"
self.movements_items.destroy item
elsif not self.items.include? item
self.movements_items << item
end
end
end
self.update attributes
end
end
end
def check_plates
movements_items.each do |i|
i.errors.add :plate, "Plate not found" if StorageItem.find_by_plate(i.plate).nil?
end
end
... other validations and callbacks ...
end
With this, the create works as I wanted, because, in case of a error, the validation adds the error to the specific item attribute. But the update does not because it has to add the error to the base of the movement, since there is no item.
I made a real basic github project here that demonstrates the issue. Basically, when I create a new comment, it is saved as expected; when I update an existing comment, it isn't saved. However, that isn't what the docs for :autosave => true say ... they say the opposite. Here's the code:
class Post < ActiveRecord::Base
has_many :comments,
:autosave => true,
:inverse_of => :post,
:dependent => :destroy
def comment=(val)
obj=comments.find_or_initialize_by(:posted_at=>Date.today)
obj.text=val
end
end
class Comment < ActiveRecord::Base
belongs_to :post, :inverse_of=>:comments
end
Now in the console, I test:
p=Post.create(:name=>'How to groom your unicorn')
p.comment="That's cool!"
p.save!
p.comments # returns value as expected. Now we try the update case ...
p.comment="But how to you polish the rainbow?"
p.save!
p.comments # oops ... it wasn't updated
Why not? What am I missing?
Note if you don't use "find_or_initialize", it works as ActiveRecord respects the association cache - otherwise it reloads the comments too often, throwing out the change. ie, this implementation works
def comment=(val)
obj=comments.detect {|obj| obj.posted_at==Date.today}
obj = comments.build(:posted_at=>Date.today) if(obj.nil?)
obj.text=val
end
But of course, I don't want to walk through the collection in memory if I could just do it with the database. Plus, it seems inconsistent that it works with new object but not an existing object.
Here is another option. You can explicitly add the record returned by find_or_initialize_by to the collection if it is not a new record.
def comment=(val)
obj=comments.find_or_initialize_by(:posted_at=>Date.today)
unless obj.new_record?
association(:comments).add_to_target(obj)
end
obj.text=val
end
I don't think you can make this work. When you use find_or_initialize_by it looks like the collection is not used - just the scoping. So you are getting back a different object.
If you change your method:
def comment=(val)
obj = comments.find_or_initialize_by(:posted_at => Date.today)
obj.text = val
puts "obj.object_id: #{obj.object_id} (#{obj.text})"
puts "comments[0].object_id: #{comments[0].object_id} (#{comments[0].text})"
obj.text
end
You'll see this:
p.comment="But how to you polish the rainbow?"
obj.object_id: 70287116773300 (But how to you polish the rainbow?)
comments[0].object_id: 70287100595240 (That's cool!)
So the comment from find_or_initialize_by is not in the collection, it outside of it. If you want this to work, I think you need to use detect and build as you have in the question:
def comment=(val)
obj = comments.detect {|c| c.posted_at == Date.today } || comments.build(:posted_at => Date.today)
obj.text = val
end
John Naegle is right. But you can still do what you want without using detect. Since you are updating only today's comment you can order the association by posted_date and simply access the first member of the comments collection to updated it. Rails will autosave for you from there:
class Post < ActiveRecord::Base
has_many :comments, ->{order "posted_at DESC"}, :autosave=>true, :inverse_of=>:post,:dependent=>:destroy
def comment=(val)
if comments.empty? || comments[0].posted_at != Date.today
comments.build(:posted_at=>Date.today, :text => val)
else
comments[0].text=val
end
end
end
I have two different objects which can belong to one parent object. These child objects can both also belong to each other (many to many). What's the best way to ensure that child objects which belong to each other also belong to the same parent object.
As an example of what I'm trying to do I have a Kingdom which has both many People and Land. The People model would have a custom validate which checks each related Land and error.adds if one has a mismatched kingdom_id. The Land model would have a similar validate.
This seems to work, but when updating it allows the record to save the 'THIS IS AN ERROR' error is in people.errors, however the Land which raised the error has been added to the People collection.
kingdom = Kingdom.create
people = People.create(:kingdom => kingdom)
land = Land.create(:kingdom_id => 999)
people.lands << land
people.save
puts people.errors.inspect # #messages={:base=>["THIS IS AN ERROR"]
puts people.lands.inspect # [#<Land id: 1...
Ideally I'd want the error to cancel the record update. Is there another way I should be going about this, or am I going in the wrong direction entirely?
# Models:
class Kingdom < ActiveRecord::Base
has_many :people
has_many :lands
end
class People < ActiveRecord::Base
belongs_to :kingdom
has_and_belongs_to_many :lands
validates :kingdom_id, :presence => true
validates :kingdom, :associated => true
validate :same_kingdom?
private
def same_kingdom?
if self.lands.any?
errors.add(:base, 'THIS IS AN ERROR') unless kingdom_match
end
end
def kingdom_match
self.lands.each do |l|
if l.kingdom_id != self.kingdom_id
return false
end
end
end
end
class Land < ActiveRecord::Base
belongs_to :kingdom
has_and_belongs_to_many :people
end
Firstly, the validation won't prevent the record from being added to the model's unpersisted collection. It will prevent the revised collection from being persisted to the database. So the model will be in an invalid state, and flagged as such with the appropriate errors. To see this, you can simply reload the people object.
You also have an error in your logic - the kingdom_match method will never return true even if no invalid kingdom_id's are found. You should add a line to fix this:
def kingdom_match
self.lands.each do |l|
return false if l.kingdom_id != self.kingdom_id
end
true
end
And you can make this validation a bit more concise and skip the kingdom_match method entirely:
def same_kingdom?
if self.lands.any?{|l| l.kingdom_id != self.kingdom_id }
errors.add(:base, 'THIS IS AN ERROR')
end
end
I'm having some issues in RoR with some model methods I am setting. I'm trying to build a method on one model, with an argument that gets supplied a default value (nil). The ideal is that if a value is passed to the method, it will do something other than the default behavior. Here is the setup:
I currently have four models: Market, Deal, Merchant, and BusinessType
Associations look like this:
class Deal
belongs_to :market
belongs_to :merchant
end
class Market
has_many :deals
has_many :merchants
end
class Merchant
has_many :deals
belongs_to :market
belongs_to :business_type
end
class BusinessType
has_many :merchants
has_many :deals, :through => :merchants
end
I am trying to pull some data based on Business Type (I have greatly simplified the return, for the sake of brevity):
class BusinessType
def revenue(market=nil)
if market.nil?
return self.deals.sum('price')
else
return self.deals(:conditions => ['market_id = ?',market]).sum('price')
end
end
end
So, if I do something like:
puts BusinessType.first.revenue
I get the expected result, that is the sum of the price of all deals associated with that business type. However, when I do this:
puts BusinessType.first.revenue(1)
It still returns the sum price of all deals, NOT the sum price of all deals from market 1. I've also tried:
puts BusinessType.first.revenue(market=1)
Also with no luck.
What am I missing?
Thanks!
Try this:
class BusinessType
def revenue(market=nil)
if market.nil?
return self.deals.all.sum(&:price)
else
return self.deals.find(:all, :conditions => ['market_id = ?',market]).sum(&:price)
end
end
end
That should work for you, or at least it did for some basic testing I did first.
As I have gathered, this is because the sum method being called is on enumerable, not the sum method from ActiveRecord as you might have expected.
Note:
I just looked a bit further, and noticed you can still use your old code with a smaller tweak than the one I noted:
class BusinessType
def revenue(market=nil)
if market.nil?
return self.deals.sum('price')
else
return self.deals.sum('price', :conditions => ['market_id = ?', market])
end
end
end
Try this!
class BusinessType
def revenue(market=nil)
if market.nil?
return self.deals.sum(:price)
else
return self.deals.sum(:price,:conditions => ['market_id = ?',market])
end
end
end
You can refer this link for other functions. http://en.wikibooks.org/wiki/Ruby_on_Rails/ActiveRecord/Calculations
I have two models with a HABTM association, let´s say book and author.
class Book
has_and_belongs_to_many :authors
end
class Author
has_and_belongs_to_many :books
end
The author has a set of attributes (e.g. first-name,last-name,age) that can all be blank (see validation).
validates_length_of :first_name, :maximum => 255, :allow_blank => true, :allow_nil => false
In the books_controller, I do the following to append all authors to a book in one step:
#book = Book.new(params[:book])
#book.authors.build(params[:book][:authors].values)
My question: What would be the easiest way to avoid the saving of authors which fields are all blank to prevent too much "noise" in the database?
At the moment, I do the following:
validate :must_have_some_data
def must_have_some_data
empty = true
hash = self.attributes
hash.delete("created_at")
hash.delete("updated_at")
hash.each_value do |value|
empty = false if value.present?
end
if (empty)
errors.add_to_base("Fields do not contain any data.")
end
end
Maybe there is an more elegant, Rails-like way to do that.
Thanks.
A little shorter
def must_have_some_data
hash = self.attributes
hash.delete("created_at")
hash.delete("updated_at")
errors.add_to_base("Fields do not contain any data.") if hash.select{|k,v| !v.blank?}.empty?
end
Actually I think, that you should validate not all attributes, but just specific attributes, which you are expecting to presence
def must_have_some_data
valid_fields = ['first_name', 'second_name', 'last_name']
errors.add_to_base("Fields do not contain any data.") if self.attributes.select{|k,v| valid_fields.include? k and !v.blank?}.empty?
end
UPD
In this situation you should also check authors fields in controller. So your authors fields must be in separate params group.
def create
book = Book.new(params[:book])
params[:authors].each do |author|
book.authors.build(author) unless author.attributes.each{|k,v| !v.blank?}.empty?
end
if book.save
...
end
end
put this in the books model:
validates_associated :authors, :on => :create
Unless you want invalid author objects to be silently ignored but not saved. Then the current solution is one way of solving it.
What version of rails are you using? accepts_nested_attributes_for might be of use in this situation.
You can change one line :)
def create
book = Book.new(params[:book])
params[:authors].each do |author|
# book.authors.build(author) unless author.attributes.each{|k,v| !v.blank?}.empty?
book.authors.build(author) unless author.all? {|key,val| val.empty?}
end
if book.save
...
end
end