user first_name last_name fields to create a full_

问题:

I have first_name and last_name fields currently represented in my model in rails. I'd like to add another field to my database called full_name and was wondering what the best way to do this seamlessly would be. Mind you I also have a production server going and would like to make it so that I not only add a column in my migration, but also can populate the new field with the existing data.

EDIT:

Here's my controller

def followers
    @title = "Followers"
    @user = User.find(params[:id])
    @users = @user.followers.paginate(page: params[:page])
    @followers = @user.followers.find(:all, :select => 'users.id, users.first_name, users.last_name', :conditions => ["users.first_name like ?","%" + params[:q] + "%"])

    respond_to do |format|
      format.html {render 'show_follow'}
      format.json {render :json => @followers}
    end
end

I want to be able to 1. select: 'users.id, users.full_name and 2. :condition =>["users.full_name like ?", ...] and the only way I can think to do this is to modify the model. I also only want to return the properties id and full_name in the json object.

回答1:

You will probably be better off just defining a full_name method in your model:

def full_name                                                                                                                                                                                     
  ([first_name, last_name] - ['']).compact.join(' ')                         
end

You can search by full name with something like:

def self.find_all_by_name_containing(text)
  self.where("LOWER(first_name || ' ' || last_name) LIKE ?", "%#{text.downcase}%")
end

Then define your own #to_json

回答2:

If you really want to go ahead with adding a full_name field to your User model, then I suggest the following steps.

1.Generate a rails migration adding the field full_name to users table.

rails g migration add_full_name_to_users full_name:string

2.Add the following before_save callback to your User model.

Class User < ActiveRecord::Base
  ...

  before_save :set_full_name

  private
  def set_full_name
    self.full_name = "#{self.first_name} #{self.last_name}".strip
  end
end

3.Commit, push code to production, run migration on production.

4.Run a save or save! method on all your users in rails console.

$> User.find_each(:batch_size => 1000){ |user| user.save }

I guess, that should take care of updating your existing users, plus the before_save call will take care of future additions/updates.

回答3:

Generate migration

rails g migration add_full_name_to_users

Inside migration:

def up
  add_column :users, :full_name, :string
  execute <<-SQL
    UPDATE users SET full_name = first_name||' '||last_name WHERE full_name IS NULL;
  SQL
end

It will create full_name column and populate it with default data. You can also do something like this in ruby but it will be much faster in SQL.