I have refined the Enumerable module in a Rails controller as follows, adding one method that, as far as I know, doesn't already exist in Rails or the standard library:
module OrderedGroupBy
refine Enumerable do
def ordered_group_by(&block)
items = each
groups = []
prev = nil
loop do
begin
i = items.next
current = i.instance_eval(&block)
groups << [] if current != prev
prev = current
groups.last << i
rescue StopIteration
break
end
end
groups
end
end
end
using OrderedGroupBy
class TestController < ApplicationController
def test
numbers = ['one', 'three', 'seven', 'four', 'nine']
#groups = numbers.ordered_group_by(&:length)
end
end
Calling the controller action test results in a NoMethodError:
undefined method `ordered_group_by' for ["one", "three", "seven", "four", "nine"]:Array
To narrow down the problem, I created a standalone file with the same structure (without the Rails environment):
module OrderedGroupBy
refine Enumerable do
def ordered_group_by(&block)
items = each
groups = []
prev = nil
loop do
begin
i = items.next
current = i.instance_eval(&block)
groups << [] if current != prev
prev = current
groups.last << i
rescue StopIteration
break
end
end
groups
end
end
end
using OrderedGroupBy
class TestController < Object
def test
numbers = ['one', 'three', 'seven', 'four', 'nine']
#groups = numbers.ordered_group_by(&:length)
end
end
TestController.new.test
In this case, calling the test method has the expected result:
# => [["one"], ["three", "seven"], ["four", "nine"]]
Also, if I define the ordered_group_by method directly on Enumerable, without using refine, I can successfully call the method.
Is there some reason why this would not work as a refinement in the context of Rails, or is there something else I'm missing?
Edit: I'm using rails 5.2.0, and this is an empty project, with only rails new _ and rails generate controller Test test having been run.
Related
So I have two files, one called a.rb and one called b.rb. Here's the contents in both:
# a.rb
class A
def initialize
#variable = ""
#module_b = B.new(self)
end
def pass_to_b(self)
#module_b.do_something(#variable)
end
def set_variable(var)
# var = empty
#variable = var
end
end
and
# b.rb
class B
def initialize(module_a)
#module_a = module_a
end
def set_variable_in_a(data)
#module_a.set_variable(data)
end
def do_something(variable)
# variable = empty
set_variable_in_a("hello world")
end
end
This is just an example of what I'm dealing with. If I'm trying to start a function in Class A, which is supposed to do something in ClassB and then change an instance variable in Class A, I'm not sure how to do this properly. This is what I've tried, however:
a = A.new
a.pass_to_b
Class B cannot see the instance variable #variable, and if it tries to set_variable_in_a, that doesn't work either. It's like the do_something function in Class A successfully calls the do_something function in Class B, but the instance variable information is not available. I thought by passing self to Class B, we'd be able to at least call the function
My MRI throws exeption about
def pass_to_b(self)
because you can't pass self to method as argument.
You need delete 'self' how argument
Run code below and you will see that #variable of instance of Class A has '123hello world' string
class A
def initialize
#variable = "123"
#module_b = B.new(self)
end
def pass_to_b
#module_b.do_something(#variable)
end
def set_variable(var)
# var = empty
#variable = var
end
end
# b.rb
class B
def initialize(module_a)
#module_a = module_a
end
def set_variable_in_a(data)
#module_a.set_variable(data)
end
def do_something(variable)
set_variable_in_a(variable + "hello world")
end
end
a = A.new
a.pass_to_b
display variable 'a' and you will see something like this
#<A:0x00007fdaba0f3c90 #variable="123hello world", #module_b=#<B:0x00007fdaba0f3c40 #module_a=#<A:0x00007fdaba0f3c90 ...>>>
In Ruby 2.1.5 and 2.2.4, creating a new Collector returns the correct result.
require 'ostruct'
module ResourceResponses
class Collector < OpenStruct
def initialize
super
#table = Hash.new {|h,k| h[k] = Response.new }
end
end
class Response
attr_reader :publish_formats, :publish_block, :blocks, :block_order
def initialize
#publish_formats = []
#blocks = {}
#block_order = []
end
end
end
> Collector.new
=> #<ResourceResponses::Collector>
Collector.new.responses
=> #<ResourceResponses::Response:0x007fb3f409ae98 #block_order=[], #blocks= {}, #publish_formats=[]>
When I upgrade to Ruby 2.3.1, it starts returning back nil instead.
> Collector.new
=> #<ResourceResponses::Collector>
> Collector.new.responses
=> nil
I've done a lot of reading around how OpenStruct is now 10x faster in 2.3 but I'm not seeing what change was made that would break the relationship between Collector and Response. Any help is very appreciated. Rails is at version 4.2.7.1.
Let's have a look at the implementation of method_missing in the current implementation:
def method_missing(mid, *args) # :nodoc:
len = args.length
if mname = mid[/.*(?==\z)/m]
if len != 1
raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
end
modifiable?[new_ostruct_member!(mname)] = args[0]
elsif len == 0
if #table.key?(mid)
new_ostruct_member!(mid) unless frozen?
#table[mid]
end
else
err = NoMethodError.new "undefined method `#{mid}' for #{self}", mid, args
err.set_backtrace caller(1)
raise err
end
end
The interesting part is the block in the middle that runs when the method name didn't end with an = and when there are no addition arguments:
if #table.key?(mid)
new_ostruct_member!(mid) unless frozen?
#table[mid]
end
As you can see the implementation first checks if the key exists, before actually reading the value.
This breaks your implementation with the hash that returns a new Response.new when a key/value is not set. Because just calling key? doesn't trigger the setting of the default value:
hash = Hash.new { |h,k| h[k] = :bar }
hash.has_key?(:foo)
#=> false
hash
#=> {}
hash[:foo]
#=> :bar
hash
#=> { :foo => :bar }
Ruby 2.2 didn't have this optimization. It just returned #table[mid] without checking #table.key? first.
I've got a Paypal IPN that comes into a PaymentNotificationsController in my app. However, some variables depend on the number of items in a cart, so i want to extract them before creating the PaymentNotification.
So far, i've got:
class PaymentNotificationsController < ApplicationController
protect_from_forgery except: [:create]
def create
PaymentNotification.create!(params: params,
item_number: params[:item_number], item_name: params[:item_name], quantity: params[:quantity]
render nothing: true
end
end
However, when the notification comes from PayPal, it comes in the form of item_name1, item_number1, quantity1, item_name2, item_number2, quantity2 and so on.
Even if its just one item, it would come as item_name1, item_number1, quantity1, option1 and so on.
I have this function to try and extract the variables, but i don't know how to trigger the function. I tried using a before_action at the top of the controller but it didn't work. Returned wrong number of arguments(0 for 1):
ITEM_PARAM_PREFIXES = ["item_name", "item_number", "quantity"]
def extract_ipn_items_params(params)
item_params = []
loop do
item_num_to_test = item_params.length + 1
item_num_suffix = item_num_to_test.to_s
possible_param_name = ITEM_PARAM_PREFIXES[0] + item_num_suffix
if params.include?(possible_param_name)
this_item_params = {}
ITEM_PARAM_PREFIXES.each do |prefix|
this_item_params[prefix] = params[prefix + item_num_suffix]
end
item_params.push this_item_params
else
return item_params
end
end
end
So i'm asking, how do i trigger the function to extract the variables and put them into params[:item_number], params[:item_name], params[:quantity] for each item in the cart so if there are two items, two separate PaymentNotifications would be created?
Note: Both methods are in the same PaymentNotificationsController.
Any help would be appreciated. Thanks in advance!
I assume your method extract_ipn_items_params already fetches the data you require, you can remove the params argument to the method, as the params is always available in the actions/methods of the controller.
ITEM_PARAM_PREFIXES = ["item_name", "item_number", "quantity"]
def extract_ipn_items_params
mod_params = Hash.new{|k, v| k[v] = {} }
ITEM_PARAM_PREFIXES.each do |item_data_key|
key_tracker = 1
loop do
current_key = (item_data_key + key_tracker.to_s).to_sym
if params.include? current_key
mod_params[key_tracker][item_data_key] = params[current_key]
else
break
end
key_tracker += 1
end
end
mod_params
end
The method returns a hash of hashes like:
{1 => {item_name: 'Item 1', item_number: 1084, quantity: 15}}, if you have nested attributes set up for a user, I think you should be able to do something like, not really sure, but should be possible:
user.update(payment_notifications_attributes: extract_ipn_items_params)
Let me know if that works for you.
UPDATE
Based on the Github Gist, here's something I was able to come up with:
class PaymentNotificationsController < ApplicationController
protect_from_forgery except: [:create]
ITEM_PARAM_PREFIXES = ["item_name", "item_number", "quantity", "option_name"]
def create
extract_ipn_items_params.each do |key, values|
# this approach loops through all the returned results, nested attributes may help abstract this though
PaymentNotification.create(values)
render nothing: true
end
def details
# params.extract_ipn_items_params #this doesn't exist as params is an instance of ActionController::Parameters
PaymentNotification.update_attributes(line_item_id: params[:item_number], product_title: params[:item_name], option_name: params[:option_name], quantity: params[:quantity])
end
private
def additional_attributes
# create this for additional merge attributes. A better place for these would be the parent of this
{
params: params,
cart_id: params[:invoice],
status: params[:payment_status],
transaction_id: params[:txn_id],
first_name: params[:first_name],
last_name: params[:last_name],
email: params[:payer_email],
address_name: params[:address_name],
address_street: params[:address_street],
address_city: params[:address_city],
address_state: params[:address_state],
address_zip: params[:address_zip],
address_country: params[:address_country]
}
end
def extract_ipn_items_params
mod_params = Hash.new{|k, v| k[v] = {}.merge(additional_attributes) }
ITEM_PARAM_PREFIXES.each do |item_data_key|
key_tracker = 1
loop do
current_key = (item_data_key + key_tracker.to_s).to_sym
if params.include? current_key
mod_params[key_tracker][item_data_key] = params[current_key]
else
break
end
key_tracker += 1
end
end
mod_params
end
end
Let me know if that fixes your problem.
You should have payment_id so you can find it by using gem 'paypal-sdk-rest'
payment = PayPal::SDK::REST::Payment.find payment_id
then you could see all details in payment object
I am a complete beginner to Ruby. I am working on Lesson 45 of Learn Ruby the Hard Way currently and am creating a game similar to Zork and Adventure.
I have created a structure where I am creating 'scenes' in different files and requiring all the scenes in one file where I have an engine/map that ensures if the current scene does not equal 'finished' that it runs 'X' scene's 'enter' method.
However I have two issues:
1) I keep getting a error saying 'Warning class variable access from top level'
2) Even though the script is running I get
ex45.rb:30:in `play': undefined method `enter' for nil:NilClass (NoMethodError) from ex45.rb:59:in
The following is all of my code from each file. My apologies if it's a long read, but I would love to know why I am getting these two errors and what I can do to fix them.
Ex45.rb:
require "./scene_one.rb"
require "./scene_two.rb"
require "./scene_three.rb"
##action = SceneOne.new
##action_two = SceneTwo.new
##action_three = SceneThree.new
class Engine
def initialize(scene_map)
#scene_map = scene_map
end
def play()
current_scene = #scene_map.opening_scene()
last_scene = #scene_map.next_scene('finished')
while current_scene != last_scene
next_scene_name = current_scene.enter()
current_scene = #scene_map.next_scene(next_scene_name)
end
current_scene.enter()
end
end
class Map
##scenes = {
'scene_one' => ##action,
'scene_two' => ##action_two,
'scene_three' => ##action_three
}
def initialize(start_scene)
#start_scene = start_scene
end
def next_scene(scene_name)
val = ##scenes[scene_name]
return val
end
def opening_scene()
return next_scene(#start_scene)
end
end
a_map = Map.new('scene_one')
a_game = Engine.new(a_map)
a_game.play()
scene_one.rb:
class SceneOne
def enter
puts "What is 1 + 2?"
print "> "
answer = $stdin.gets.chomp
if answer == "3"
puts "Good job"
return 'scene_two'
else
puts "try again"
test
end
end
end
scene_two.rb
class SceneTwo
def enter
puts "1 + 3?"
print "> "
action = $stdin.gets.chomp
if action == "4"
return 'scene_three'
else
puts "CANNOT COMPUTE"
end
end
end
scene_three.rb
class SceneThree
def enter
puts "This is scene three"
end
end
Thanks in advance!
Answer to your first question:
You need to move the class variable definitions inside your Map class to get rid of these warnings:
Ex45.rb:5: warning: class variable access from toplevel
Ex45.rb:6: warning: class variable access from toplevel
Ex45.rb:7: warning: class variable access from toplevel
So, your Map class would look like this:
class Map
##action = SceneOne.new
##action_two = SceneTwo.new
##action_three = SceneThree.new
##scenes = {
'scene_one' => ##action,
'scene_two' => ##action_two,
'scene_three' => ##action_three
}
def initialize(start_scene)
#start_scene = start_scene
end
def next_scene(scene_name)
val = ##scenes[scene_name]
return val
end
def opening_scene()
return next_scene(#start_scene)
end
end
To answer your 2nd question:
You are getting undefined method 'enter' for nil:NilClass (NoMethodError) because your current_scene becomes nil at some point and then you try to call: current_scene.enter() i.e. nil.enter and it fails with that error message.
To solve this problem, you have to make sure you always have some value in your current_scene i.e. make sure it's not nil.
I think, you can just remove current_scene.enter() line from the end of your play method in the Engine class. So, your Engine class will look like this:
class Engine
def initialize(scene_map)
#scene_map = scene_map
end
def play()
current_scene = #scene_map.opening_scene()
last_scene = #scene_map.next_scene('finished')
while current_scene != last_scene
next_scene_name = current_scene.enter()
current_scene = #scene_map.next_scene(next_scene_name)
end
# current_scene.enter()
end
end
And, you won't get that error anymore.
Just so you know:
##y = 20
p Object.class_variables
--output:--
1.rb:1: warning: class variable access from toplevel
[:##y]
And:
class Object
def self.y
##y
end
end
puts Object.y
--output:--
20
But:
class Dog
##y = "hello"
def self.y
##y
end
end
puts Dog.y #=>hello
puts Object.y #=>What do you think?
The output of the last line is the reason that class variables are not used in ruby. Instead of class variables, you should use what are known as class instance variables:
class Object
#y = 10 #class instance variable
def self.y
#y
end
end
puts Object.y
class Dog
#y = "hello"
def self.y
#y
end
end
puts Dog.y #=> hello
puts Object.y #=> 10
A class instance variable is just an #variable that is inside the class, but outside any def. And instead of there being one ##variable that is shared by all the subclasses, each subclass will have its own #variable.
Building a Rails 3.2 app with Ruby 1.9.
I am trying to write a helper method that initializes 3 variables and when i try to call the initialized variables from my view i get an "undefined method" error.
Method In Helper File
module StoreHelper
class Status
def initialize(product)
product_sales = product.line_items.total_product_sale.sum("quantity")
#avoid nil class errors for vol2 and 3. volume 1 can never be nil
if product.volume2.nil?
product.volume2 = 0
end
if product.volume3.nil?
product.volume3 = 0
end
#Promo status logic
if (product_sales >= product.volume2) && (product_sales < product.volume3)
#level3_status = "Active"
#level2_status = "On!"
#level1_status = "On!"
elsif (product_sales >= product.volume3)
#level3_status = "On!"
#level2_status = "On!"
#level1_status = "On!"
else #level3_status = "Pending"
end
end
I then attempt to call the the initialized variable #level3_status like so
<%=level3_status (product)%>
Not sure what i'm doing wrong any help would be appreciated.
How long are you programming with ruby? You have to create a new instance of your class to access the instance outside. Take a look at these basics: http://www.tutorialspoint.com/ruby/ruby_variables.htm
UPDATE
From the link above..
Ruby Instance Variables:
Instance variables begin with #. Uninitialized instance variables have the value nil and produce warnings with the -w option.
Here is an example showing usage of Instance Variables.
class Customer
def initialize(id, name, addr)
#cust_id=id
#cust_name=name
#cust_addr=addr
end
def display_details()
puts "Customer id ##cust_id"
puts "Customer name ##cust_name"
puts "Customer address ##cust_addr"
end
end
# Create Objects
cust1=Customer.new("1", "John", "Wisdom Apartments, Ludhiya")
cust2=Customer.new("2", "Poul", "New Empire road, Khandala")
# Call Methods
cust1.display_details()
cust2.display_details()
That´s how you can work with ruby and instance variables. More details are in the link.
In your case I think you have another "error", you mixed a few things.. where is your helper class? Under the app/helpers/store_helper.rb? In this file you should just add view helpers. If I am right with my intuitions I would solve your problem like following:
app/helpers/store_helper.rb
module StoreHelper
def get_level_states(product)
product_sales = product.line_items.total_product_sale.sum("quantity")
product.volume2 = 0 if product.volume2.nil?
product.volume3 = 0 if product.volume3.nil?
levels = {}
if (product_sales >= product.volume2) && (product_sales < product.volume3)
levels[:1] = "On!"
levels[:2] = "On!"
levels[:3] = "Active!"
elsif product_sales >= product.volume3
levels[:1] = "On!"
levels[:2] = "On!"
levels[:3] = "On!"
else
levels[:3] = "Pending"
end
levels
end
end
app/views/your_views_folder/your_view.html.erb
to get the different level state:
<% levels = get_level_states(product) %>
<%= levels[:1] %> # will print the level 1
<%= levels[:2] %> # will print the level 2
<%= levels[:3] %> # will print the level 3