So I have a User model and a Post model
Post belongs to a User
Post has a field in the database called score
In the Post model I have a method called score which gives the post a score based on the fields (needs to be done this way):
def score
score = 0
if self.title.present?
score += 5
end
if self.author.present?
score += 5
end
if self.body.present?
score += 5
end
score
end
The Question:
There are loads of Users and loads of Posts. So What I'm trying to do is after the score is worked out, I want to save it to the Post score field in the database for each Post. The score should be updated if the user updates the Post.
I have looked at using after_update :score! but don't understand how to apply the logic
It looks a little like you are trying to re-invent the wheel ActiveRecord provides you.
If you have a database field score, then ActiveRecord will automatically provide an attribute_reader and attribute_writer for score and you should not override these unless you have a really really good reason for it, e.g. you need to add some other resources or some serious business logic into it.
There is a way easier way to solve it, by using the before_save hook, which will kick in before any #create or #update:
class Post
attribute_accessible :score # if you have Rails 4.x you can omit this line
before_save :update_score
private
def update_score
new_score = 0
self.score = [:title, :author, :body].each do |field|
new_score += 5 if send(field).present?
end
self.score = new_score
end
This way, ActiveRecord will handle the saving for you and your score will always up to date. Additionally Post#score will always return the real value currently saved in the database
You can do it like this
after_update :score!
def score!
score = 0
if self.title.present?
score += 5
end
if self.author.present?
score += 5
end
if self.body.present?
score += 5
end
self.update_column(:score, score)
end
This is to be done in your Post model.
You can do it using update_column method. Like:
def score
score = 0
if self.title.present?
score += 5
end
if self.author.present?
score += 5
end
if self.body.present?
score += 5
end
self.update_column(:score, score)
end
You need to override the setter method in the Post model
attr_accessible :score
def score=(value)
score = 0
if self.title.present?
score += 5
end
if self.author.present?
score += 5
end
if self.body.present?
score += 5
end
write_attribute(:score, score)
end
Related
Pretty new to RoR. Wonder if anyone can help me with this issue.
I got a gem called "business_time" which calculates the business days between two dates. I have set up a method in the model which does all the calculations.
I have a field called "credit" which should hold the number of business days. Here's what I have:
MODEL
def self.calculate(from_date,to_date)
days = 0
date_1 = Date.parse(from_date)
date 2 = Date.parse(to_date)
days = date_1.business_days_until(date2)
days
end
CONTROLLER
def new
#vacation = current_user.vacations.build
#vacations = Vacation.calculate(:from_date, :to_date)
end
I got an error referencing something about a string.
Furthermore, how do I go about storing the data from the method into the field called "credit"?
Thanks guys.
I think there is no need for an extra method, since all attributes (from_date, end_date and credit) are stored in the same model.
I would just set from_date and end_date in the initializer and calculate credit with a callback before validation:
# in the model
before_validation :calculate_credit
private
def calculate_credit
if from_date && to_date
# `+ 1` because the user takes off both days (`from_date` and `to_date`),
# but `business_days_until` doesn't count the `from_day`.
self.credit = from_date.business_days_until(to_date) + 1
end
end
# in the controller
def new
#vacation = current_user.vacations.build
end
def create
#vacation = current_user.vacations.build(vacation_params)
if #vacation.save
# #vacation.credit would return the calculated credit at this point
else
# ...
end
end
private
def vacation_params
params.require(:vacation).permit(:from_date, :to_date)
end
What you need here is pass String objects instead of Symbol objects.
So instead of #vacations = Vacation.calculate(:from_date, :to_date), you probably need to pass params[:from_date] and params[:to_date] which should be strings like 20/01/2016, etc...
Your code should be
#vacations = Vacation.calculate(params[:from_date], params[:to_date])
I'm using optimistic locking on a Rails model. Inside of a loop, I update and save this model (or, rather, many instances of this model).
From inside the loop, I output the "before" and "after" values, and the field appears to be updated correctly. But afterward, when I find the models by ID, I see that the field is not updated. Can anyone spot my error?
class Usage::LeadDistributionWeight < ActiveRecord::Base
attr_accessible :agent_id, :tag_value_id, :weight, :premium_limit, :countdown, :lock_version, :tag_value
def increment_countdown!
self.countdown = self.countdown + self.weight
save
rescue ActiveRecord::StaleObjectError
attempts_to_crement_countdown ||= 0
attempts_to_crement_countdown += 1
self.increment_countdown! unless attempts_to_crement_countdown > 5
false
end
def self.increment_countdowns parent_id, lead_type_id
if lead_type_id.present?
joins(:agent)
.where("#{reflect_on_association(:agent).table_name}.parent_id = ?", parent_id)
.where(tag_value_id:lead_type_id)
.all(readonly:false).each { |weight|
prev = weight.countdown
if weight.increment_countdown!
puts "#{prev} differs from #{weight.countdown}"
else
puts "no difference!"
end
}
end
end
end
Why do I get empty when I execute this? Asumming User's point is 2500. It should return 83
posts_controller
#user = User.find(params[:id])
#user.percentage = count_percentage(#user)
#user.save
application_controller
def count_percentage(user)
if user
if user.point > 2999
percentage = ((user.point / 5000.0) * 100 ).to_i
elsif user.point > 1999
percentage = ((user.point / 3000.0) * 100 ).to_i
end
return percentage
end
end
It looks like there is some lack of basic understanding, so I try to focus on a few points here.
count_percentage belongs to your model. It is a method which does things that are tied to your User records. In your example, the code can only be used with a User record. Therefore it belongs to your User class!
class User < ActiveRecord::Base
def percentage
if self.point > 2999
return ((self.point / 5000.0) * 100 ).to_i
elsif user.point > 1999
return ((self.point / 3000.0) * 100 ).to_i
else
# personally, I'd add a case for points range 0...3000
end
end
As you said, you want to put that value into your "side menu", so this allows to e.g #user.percentage there which gives you the desired percentage.
According to your description (if I understood it the right way) you want to store the calculated value in your user model. And here we go again: Model logic belongs into your model class. If you want to keep your percentage value up to date, you'd add a callback, like:
class User < ActiveRecord::Base
before_save :store_percentage
def precentage
# your code here
end
private
def store_percentage
self.my_percentage_field_from_my_database = self.percentage
end
end
To your actual problem: user.point may be NULL (db) / nil (ruby), so you should convert it to_i before actually calculating with it. Also that's why I've suggested an else block in your condition; To return a value wether or not your user.point is bigger than 1999 (if it even is an integer.. which I doubt in this case).
To answer on this question you should try to examine user.point, percentage value in the count_percentage method.
I strongly recommend pry. Because it's awesome.
I have a User model with Profit field. Profit field is a DECIMAL (11,0) type. I have a masked input on the form which allows user to input something like $1,000. I want to format that value and remove everything except numbers from it so i will have 1000 saved. Here is what i have so far:
class User < ActiveRecord::Base
before_save :format_values
private
def format_values
self.profit.to_s.delete!('^0-9') unless self.profit.nil?
end
end
But it keeps saving 0 in database. Looks like it is converting it to decimal before my formatting function.
Try this:
def profit=(new_profit)
self[:profit] = new_profit.gsub(/[^0-9]/, '')
end
First of all, this:
def format_values
self.profit.to_s.delete!('^0-9') unless self.profit.nil?
end
is pretty much the same as this:
def format_values
return if(self.profit.nil?)
p = self.profit
s = p.to_s
s.delete!('^0-9')
end
So there's no reason to expect your format_values method to have any effect whatsoever on self.profit.
You could of course change format_values to assign the processed string to self.profit but that won't help because your cleansing logic is in the wrong place and it will be executed after '$1,000' has been turned into a zero.
When you assign a value to a property, ActiveRecord will apply some type conversions along the way. What happens when you try to convert '$1,000' to a number? You get zero of course. You can watch this happening if you play around in the console:
> a = M.find(id)
> puts a.some_number
11
> a.some_number = 'pancakes'
=> "pancakes"
> puts a.some_number
0
> a.some_number = '$1,000'
=> "1,000"
> puts a.some_number
0
> a.some_number = '1000'
=> "1000"
> puts a.some_number
1000
So, your data cleanup has to take place before the data goes into the model instance because as soon as AR gets its hands on the value, your '$1,000' will become 0 and all is lost. I'd put the logic in the controller, the controller's job is to mediate between the outside world and the models and data formatting and mangling certainly counts as mediation. So you could have something like this in your controller:
def some_controller
fix_numbers_in(:profit)
# assign from params as usual...
end
private
def fix_numbers_in(*which)
which.select { |p| params.has_key?(p) }.each do |p|
params[p] = params[p].gsub(/\D/, '') # Or whatever works for you
end
end
Then everything would be clean before ActiveRecord gets its grubby little hands on your data and makes a mess of things.
You could do similar things by overriding the profit= method in your model but that's really not the model's job.
class User < ActiveRecord::Base
before_save :format_values
private
def format_values
self.profit = profit.to_s.gsub(/\D/,'') if profit
end
end
def format_values
self.profit.to_d!
end
I recommend you to write custom setter for this particular instance variable #profit:
class User
attr_accessor :profit
def profit= value
#profit = value.gsub(/\D/,'')
end
end
u = User.new
u.profit = "$1,000"
p u.profit # => "1000"
I would suggest using the rails helper of number with precision. Below is some code.
Generic Example:
number_with_precision(111.2345, :precision => 1, :significant => true) # => 100
Rails code Example:
def profit=(new_profit)
number_with_precision(self[:profit], :precision => 1, :significant => true)
end
I would like to sort my links using an algorithm, all the information needed can be derived from values in my Links table. How can I return items sorted by the item's calculated Score?
Schema https://gist.github.com/1326044
Index Action https://gist.github.com/1326045
Time Calculation https://gist.github.com/1326050
Algorithm
# Score = (P-1) / (T+2)^G
# P = points of an item (and -1 is to negate submitters vote)
# T = time since submission (in hours)
# G = Gravity, defaults to 1.8
I'd do as follows:
First, in your model:
after_initialize :calculate_score
attr_accessor :score
def calculate_score
unless self.new_record?
time_elapsed = (Time.zone.now - self.created_at) / 3600
self.score = (self.points-1) / (time_elapsed+2)^G # I don't know how you retrieve G
end
end
In your controller:
#links = Link.all.sort_by(&:score)