Rails How to Update a Column After Saving

Rails how to update a column after saving?

what you want is a callback. You can create an after_save callback on your Konkurrancer model, which triggers after the save() method is called for that model.

For example:

class Konkurrancer < ActiveRecord::Base
  after_save :do_foobar

  private
    def do_foobar

      rating_score = self.rating_score
      ratings = self.ratings
      rating = (rating_score/ratings)
      self.update_attributes(:ratings => rating)

    end
end

[EDIT] You should use self, since the model you are editing is the model itself. Test it out, and apply necessary logic/implementation.

Have a look at this guide for more info.

Hope that helps!

Rails after_save method trying to update record over and over

If you need to call process_pages only once after Creating a Page record and not after Updating a Page record then I would suggest to use after_create instead.

class Page < ActiveRecord::Base
  require 'open-uri'

  after_create :process_pages

  def process_pages
    self.html = open(self.url).read
    self.save
  end 
end

With after_save :process_pages, process_pages method would be called every time you save a Page record. You are saving a Page record again within process_pages method which triggers the after_save callback and you start looping.

See this SO Question for difference between after_save and after_create.
You will understand better as to why you are going in loops.

How can i update another model's data before save of one model

You can try this code. For creating transaction from user call

current_user.transaction.new(transaction_params)

Now in model transaction.rb file

class Transaction < ApplicationRecord
  belongs_to :user
  before_save :check_and_update_balance

  def check_and_update_balance
    ## since user or sender is already there no need of sender
    receiver = User.find_by(email: user_email)
    if user.has_sufficient_balance?(amount) and receiver.present?
       user.update_attributes(balance: balance - amount)
       receiver.update_attributes(balance: balance + amount)    
    end
  end
end

HOPE this Helps !!

Update a column on update of others columns properly

You can use changed_attributes

return unless (changed_attributes.keys & %w[currency price1 price2 price3 price4 price5 price6]).any?
self.prices_updated_at = Time.zone.now

Ruby on rails save a specific field in database

You can update a precise set of fields with update_attributes.

@house.update_attributes(:colour => newcolour)

You can update a single field with update_attribute.

@house.update_attribute(:colour, newcolour)

How to save another column updated time?

I would create a sub model of your Post model. Lets call it PostRecord.

So your Post model will have a has_many relationship with PostRecord, and PostRecord will belong to Post

class Post < ActiveRecord::Base
  has_many :post_records
end

class PostRecord < ActiveRecord::Base
   belongs_to :post
end

Your PostRecord model will have:

post_id as type integer 
read_at as type string

In your Post model you should define a method like this:

def updated_read_at
 self.post_record.create post_id: self.id, read_at: Time.now if read_status_changed?
end

More information on the changed? method

Update a column, all rows

Try this:

Foo.update_all(some_column: "bar")

This will generate SQL query to database:

UPDATE "foos" SET "some_column" = "bar"; 

---

Related Topics