I have the following module/class:
module Pigeons
class FedEx
attr_accessor :signature_name
def initialize(account)
self.account = account
end
def response(number)
body = "...some xml..."
return HTTParty.post('http://example.com', :body => body)
end
def track(number)
details = response(number)
self.signature_name = details[:delivery_signature_name]
end
end
end
What I'd like to be able to do is this:
#fedex ||= Pigeons::FedEx.new('123abc')
tracker = fedex.track('1234567890')
tracker.signature_name
Everything is working up until the tracker.signature_name part, which throws an undefined method 'signature_name' for nil:NilClass error.
The problem is in this line:
self.signature_name = details[:delivery_signature_name]
details[:delivery_signature_name] turns out to be nil, which is then assigned to self.signature_name and then becomes return value of track method. And here
tracker = fedex.track('1234567890')
tracker.signature_name
tracker will be nil and you try to call a method on it.
You probably meant to write this instead:
def track(number)
details = response(number)
self.signature_name = details[:delivery_signature_name]
self # <== here
end
You need two methods called signature_name= and response that do whatever they are supposed to do in your class.
Related
My service is supposed to match the current user with an opponent. I have a method in my service that is supposed to find this opponent but it's not saving it in my controller. I realize this is a very basic question but I'm very new to rails, thank you!
Here is my service:
class MatchUser
attr_accessor :user_params
def initialize(user_params)
#user_params = user_params
end
def match(opponent)
return false if user_params[:matched] == true
#unmatched_users = User.where(matched: false)
#unique_unmatched_users = #unmatched_users.where.not(id: user_params[:id])
#same_league_unmatched_users = #unique_unmatched_users.where(league_id:
user_params[:league_id])
return false if #same_league_unmatched_users.empty?
opponent = #same_league_unmatched_users.sample
opponent.faceoff_date = Time.now
user_params[:faceoff_date] = Time.now
opponent.save!
end
end
Here is the part in my controller where I'm getting an error when I try to assign #matched_user_team because #matched_user is nil
#user = current_user
#matching = MatchUser.new(#user)
if #matching.match(#matched_user)
#matched_user_team = #matched_user.teams.last.chars
end
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.
I want to assign a confirmation code to my users while creating one. And I also titleize some columns before saving-updating them. So my user.rb looks like this (it may be a bit messy):
// user.rb
*** some code ***
before_save { titleize_column(:name)
titleize_column(:surname)
capitalize_column(:complaints)
capitalize_column(:education)
capitalize_column(:job)
capitalize_column(:complaintsdetails)
capitalize_column(:prediagnosis)
capitalize_column(:existingdiagnosis)
capitalize_column(:knownilnessesother)
capitalize_column(:usedmedicine)
capitalize_column(:operation)
capitalize_column(:trauma)
capitalize_column(:allergy)
capitalize_column(:otherhabits)
capitalize_column(:motherother)
capitalize_column(:fatherother)
capitalize_column(:siblingsother)
}
before_save :generate_confirmation_code
protected
def generate_confirmation_code
unless self[:confirmed]
if(self[:type] == 'Patient')
update_attribute :confirmation_code, SecureRandom.urlsafe_base64(20)
update_attribute :confirmed, false
else
update_attribute :confirmed, true
end
end
end
protected
def capitalize_column(attr)
unless self[attr].nil?
self[attr] = Unicode::capitalize self[attr]
end
end
protected
def titleize_column(attr)
unless self[attr].nil?
words = self[attr].split
words.each_with_index do |v,i|
words[i] = Unicode::capitalize v
end
self[attr] = words.join(" ")
end
end
I'm using separate methods for titleizing and capitalizing columns because they may be nil when first creating a user, so I'm checking if it is null or not in those methods. This structure works fine on a normal signup with strong parameters. However, if I try to use twitter signup with the method below, it gives me the error 'stack level too deep' and I can see that it calls the generate_confirmation_code 123 times from the application trace and then these happens:
app/models/user.rb:83:in each'
app/models/user.rb:83:ineach_with_index'
app/models/user.rb:83:in titleize_column'
app/models/user.rb:20:inblock in '
app/models/user.rb:64:in generate_confirmation_code' (x123 times)
app/models/user.rb:101:infrom_omniauth'
app/controllers/socials_controller.rb:4:in `create'
// method for signing up/logging in a user from twitter
class << self
def from_omniauth(auth_hash)
if exists?(uid: auth_hash['uid'])
user = find_by(uid: auth_hash['uid'])
else
user = find_or_create_by(uid: auth_hash['uid'], provider: auth_hash['provider'], type: 'Patient')
user.password_digest = User.digest('111111')
user.name = auth_hash['info']['name']
user.location = get_social_location_for user.provider, auth_hash['info']['location']
user.avatar = auth_hash['info']['image']
user.url = get_social_url_for user.provider, auth_hash['info']['urls']
user.save! // THIS IS THE LINE 101!
conversation = Conversation.create()
user.conversation = conversation
admin = Admin.first
admin.conversations << conversation
user.progress = Progress.create(active_state:1)
end
user
end
I think I'm messing up by using before_save not properly, but do not know how to do it right. What am I doing wrong here?
update_attribute also fires the save callbacks, thereby looping the before_save infinitely, thus producing stack level too deep.
You can just simply assign values in a before_save callback methods, because they will simply be saved afterwards anyway. See the following:
def generate_confirmation_code
unless self[:confirmed]
if(self[:type] == 'Patient')
self.confirmation_code = SecureRandom.urlsafe_base64(20)
self.confirmed = false
else
self.confirmed = true
end
end
end
You are calling update_attribute inside before_save callback method, instead you can just assign values to attributes. The method signature generate_confirmation_code should be like below -
def generate_confirmation_code
unless self[:confirmed]
if(self[:type] == 'Patient')
self.confirmation_code = SecureRandom.urlsafe_base64(20)
self.confirmed = false
else
self.confirmed = true
end
end
end
I am trying to access variable in ruby after initialize, but i didn't get that variable , anything wrong in that?
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def self.method1(params)
Test.new(params)
#can i get that two instance variable
end
end
You should probably set up attribute accessors, then use them this way:
class Test
attr_accessor :has_test
attr_accessor :limit_test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def self.method1(params)
t = Test.new(params)
// can i get that two instance variable
// Yes:
// use t.has_test and t.limit_test
end
end
You are mixing an instance and a class method in your example.
If this is really what you want, then you have to define an accessor with attr_reader:
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
attr_reader :has_test
attr_reader :limit_test
def self.method1(params)
obj = Test.new(params)
p obj.has_test
p obj.limit_test
end
end
Test.method1(has_test: 1, limit_test: 3)
It the instance/class-method is a mistake, then this example may help you:
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def method1()
p #has_test
p #limit_test
end
end
obj = Test.new(has_test: 1, limit_test: 3)
obj.method1
If you define also the accessors like in the first code, then you have again access from outside the class.
Just in case you don't want a reader, see also Access instance variable from outside the class
Why does the following code result in the error 'undefined local variable or method `foo_client' for Foo::People:Class'
class Foo::People
class << self
def get_account_balance(account_num)
foo_client.request :get_account_balance, :body => {"AccountNum" => account_num}
end
end
def foo_client
##client ||= Savon::Client.new do|wsdl, http|
wsdl.document = PEOPLE_SERVICE_ENDPOINT[:uri] + "?WSDL"
wsdl.endpoint = PEOPLE_SERVICE_ENDPOINT[:uri]
end
end
end
def get_account_balance is inside the class << self block, so it's a class method. def foo_client is not, so it's an instance method. So you can't call foo_client from get_account_balance because you're not calling it on an instance of People.