Solved. I didn't have the initialization right, which gave the noMethodError. Then I was changing an array, but checking a variable that referred to a position in the array, and that variable had not been reassigned.
Edited to initialize bookPagesInfo, bookChaptersInfo, editPagesInfo, and editChapterInfo as suggested. Still gives the same NoMethod Error.
I have a book with page and chapter info, and want to be able to apply edits that change the number of pages, introPages, chapters, and povs.
class Book
attr_accessor :pages, :chapters, :bookPagesInfo, :bookChaptersInfo, :introPages, :povs
def initialize(bookPagesInfo, bookChaptersInfo)
#bookPagesInfo = bookPagesInfo
#bookChaptersInfo = bookChaptersInfo
#pages = bookPagesInfo[0]
#introPages = bookPagesInfo[1]
#chapters = bookChaptersInfo[0]
#povs = bookChaptersInfo[1]
end
def applyEdit(edit)
#pages += edit.new_pages
end
end
class Edit
attr_accessor :new_pages, :new_chapters, :editPagesInfo, :editChaptersInfo, :new_intro_pages, :new_povs
def initialize(editPagesInfo, editChaptersInfo)
#editPagesInfo = editPagesInfo
#editChaptersInfo = editChaptersInfo
#new_pages = editPagesInfo[0]
#new_intro_pages = editPagesInfo[1]
#new_chapters = editChaptersInfo[0]
#new_povs = editChaptersInfo[1]
end
end
The above code works for editing just number of pages. However, if I change my applyEdit method to iterate over the bookPagesInfo array, I can't get it to work. Running applyEdit below gives a nonfatal error.
def applyEdit(edit)
#bookPagesInfo.each_with_index do {|stat, idx| stat += edit.bookPagesInfo[idx]}
end
## gives undefined method `each_with_index' for nil:NilClass (NoMethodError), but
## my understanding is as long as bookPagesInfo was initialized as an array, it
## should be an array, not nilClass
I'm pretty new to classes (and this website, sorry for formatting). Thanks for the help.
You've got attr_accessors defined for :bookPagesInfo and :bookChaptersInfo, which will give you reader and writer methods, but it won't set #bookPagesInfo and #bookChaptersInfo for you in the initialize method - you need to do that yourself. So, when you try to read from the instance variable in applyEdit, you're reading nil.
Try adding
#bookPagesInfo = bookPagesInfo
#bookChaptersInfo = bookChaptersInfo
in Book#initialize.
Related
I have 3 classes: Invoice, Address and Customer (but for this problem, only the Invoice and Address class are relevant)
This is my Invoice class:
class Invoice
attr_reader :billing_address, :shipping_address, :order
def initialize(attributes = {})
#billing_address = attributes.values_at(:billing_address)
#shipping_address = attributes.values_at(:shipping_address)
#order = attributes.values_at(:order)
end
end
and this is my Address class:
class Address
attr_reader :zipcode, :full_address
def initialize(zipcode:)
#zipcode = zipcode
url = 'https://viacep.com.br/ws/' + zipcode.to_s + '/json/'
uri = URI(url)
status = Net::HTTP.get_response(uri)
if (status.code == "200")
response = Net::HTTP.get(uri)
full_address = JSON.parse(response)
#full_address = full_address
else
p "Houve um erro. API indisponível. Favor tentar novamente mais tarde."
#full_adress = nil
end
end
end
And this is my Customer class (not much relevant, but i'm showing for better explanation of the problem)
class Customer
attr_reader :name, :age, :email, :gender
def initialize(attributes = {})
#name = attributes.values_at(:name)
#age = attributes.values_at(:age)
#email = attributes.values_at(:email)
#gender = attributes.values_at(:gender)
end
end
As you can see, my Invoice class has 3 instance variables and my Address class has 2 instance variables.
So, if i test something like that:
cliente = Customer.new(name: "Lucas", age: 28, email: "abc#gmail.com", gender: "masculino")
endereco = Address.new(zipcode: 41701035)
entrega = Invoice.new(billing_address: endereco, shipping_address: endereco)
p endereco.instance_variables
[:#zipcode, :#full_address]
p entrega.shipping_address.instance_variables
[]
My instance variables can be acessed through the variable "endereco", that is an Address object, but can't be acessed through entrega.shipping_address that is also an Address object.
To be more precise, if a try this:
p entrega.shipping_address
I get this return:
[#<Address:0x00000001323d58 #zipcode=41701035, #full_address={"cep"=>"41701-035", "logradouro"=>"Rua Parati", "complemento"=>"", "bairro"=>"Alphaville I", "localidade"=>"Salvador", "uf"=>"BA", "unidade"=>"", "ibge"=>"2927408", "gia"=>""}>]
My full object are being returned, but i can't access the content of my #full_address instance variable.
If a do this:
p entrega.shipping_address.full_address
I get a NoMethodError:
solucao.rb:8:in `<main>': undefined method `full_address' for #<Array:0x000000012d25e8> (NoMethodError)
I'm trying to understand why i can't access the content inside my object if i have the full object. Maybe i'm trying to access in the wrong way, i don't know.
Can someone help ?
values_at returns an array of values (see https://apidock.com/ruby/Hash/values_at
for explanation)
Change
#shipping_address = attributes.values_at(:shipping_address)
into
#shipping_address = attributes[:shipping_address]
And that way #shipping_address will contain an Address object, not an array that contains an Address object
If you take a look at the error, it says
undefined method `full_address' for #<Array:0x000000012d25e8>
You're trying to call full_address on an array. So this means that entrega.shipping_address returns you an array (which it does, of course, take a closer look at the output).
If I were you, I'd look into how shipping_address is implemented. It's a simple attr_reader, so it's backed by an instance variable. Must be you initialize that instance variable to a wrong value (it gets an array instead of an address). Look closely at that initialization code and try to run it in IRB session. You should see the problem.
I'm new to Ruby and having a little trouble json. I have inherited my classes with custom made JSONable class, as explained HERE in this answer. I have customized it according to my need, but I couldn't figure out how to make it work with custom nested (complex) objects, according to my requirement. I have following scenario.
First Class:
class Option < JSONable
def IncludeAll=(includeAll) #bool
#includeAll = includeAll
end
def IncludeAddress=(includeAddress) #bool
#includeAddress= includeAddress
end
......
Second Class:
class Search < JSONable
def CustomerId=(customerId)
#customerId = customerId
end
def identifier=(identifier)
#identifier = identifier
end
def Options=(options) #This is expected to be of Class Option, declared above
#options = options
end
Third Class:
class Request < JSONable
def DateTimeStamp=(dateTimeStamp)
#dateTimeStamp = dateTimeStamp
end
def SDKVersion=(sDKVersion)
#sDKVersion = sDKVersion
end
def RequestMessage=(requestMessage) #This is of type Search, declared above
#requestMessage = requestMessage
end
I call it as:
search = Search.new
searchOpts = Options.new
request = Request.new
search.identifier = identifier
searchOpts.IncludeAll = false
searchOpts.IncludeAddress = true
search.Options = searchOpts #setting nested level2 property here
//THE MOST OUTER CLASS OBJECT
request.SDKVersion = "xyz"
request.RequestMessage = search #setting nested level1
My ultimate goal is to send this request object to an API, after converting it to JSON. so i call to_json on request object as:
request.to_json
But here, suggested solution in that post (JSONable) fails in this case, as it can't convert the nested complex objects request.search and request.search.Options to Json.
(gives error: in 'to_json': wrong number of arguments (1 for 0) (ArgumentError)')
What I tried:
class JSONable
def to_json
hash = {}
self.instance_variables.each do |var|
#hash[var] = self.instance_variable_get var #tried to apply following check
if((self.instance_variable_get var).instance_of? Options ||((varVal).instance_of? Search))
varVal = self.instance_variable_get var
hash[var] = varVal.to_json #convert inner object to json
else
hash[var] = self.instance_variable_get var
end
end
hash.to_json
end
.....
This converts the nested model without any problem, but it messes up the 3rd level json. The result is as following:
{"DateTimeStamp":"121212","SDKVersion":"1.5","Culture":"en","RequestMessage":"{\"identifier\":\"851848913\",\"Options\":\"{\\\"IncludeAll\\\":true,\\\"IncludeAssociatedEntities\\\":true,\\\"IncludeAddress\\\":true,\\\"IncludePaymentInstructions\\\":true}\"}"}
And API doesn't respond. It seems as it messes up the boolean variables, which should be something like:
"SearchOption":"{\"IncludeAll\":true,\"IncludeAssociatedEntities\":true,\...
but it gives:
"SearchOption\":\"{\\\"IncludeAll\\\":true,\\\"IncludeAssociatedEntities\\\":true,\\\"Includ...
So the API logic can't cast it to corresponding bool objects anymore. JSON validator also fails to validate this result, i checked online
Questions:
How can I avoid this, and produce valid JSON in this case?
How can I apply generic check to in my JSONable class to check if the object is of some custom class / complex object.
(currently i have checked only for specific classes as:)
if((self.instance_variable_get var).instance_of? Options ||((varVal).instance_of? Search))
Other Info:
It works fine for all complex objects, having no nested objects
API is developed in .NET
I'm not using Rails, its a Ruby console app (I'm new to Ruby)
The answer you referred is dated “Dec 2010.” JSON library is included in ruby stdlib for years already and it perfectly converts Hash instances to json. That said, you just need to construct hashes out of your objects and then call JSON.dump on the resulting hash. I have no idea what JSONable is and you definitely do not need it. Introduce some base class, let’s call it Base:
class Base
def to_h
instance_variables.map do |iv|
value = instance_variable_get(:"##{iv}")
[
iv.to_s[1..-1], # name without leading `#`
case value
when Base then value.to_h # Base instance? convert deeply
when Array # Array? convert elements
value.map do |e|
e.respond_to?(:to_h) ? e.to_h : e
end
else value # seems to be non-convertable, put as is
end
]
end.to_h
end
end
Now just derive your classes from Base to make them respond to to_h, define all your instance variables as you did, and call:
require 'json'
JSON.dump request.to_h # request.to_h.to_json should work as well
The above should produce the nested JSON, hashes are happily converted to json by this library automagically.
So I am trying to create a text game in ruby, and I have attempted to create a fight method that can deal with creating any object. I have a Monsters class in another file, and child classes such as Rogue and Vampire. I have managed to make this work by using a case statement that instantiates an object named m that is either Rogue or Vampire, and putting practically all the methods in the Monsters class so that they share the same method name, but is there a more efficient way of dealing with unknown objects?
My code:
def fight(monsterToFight)
case monsterToFight
when "Rogue"
m = ::Rogue.new
when "Vampire"
m = ::Vampire.new
else
puts "error 503"
end
... #more code
link to full repo: https://github.com/chaseWilliams/textGame
You can use const_get.
class_name = "Rogue"
rogue_class = Object.const_get(class_name) # => Rogue
my_rogue = rogue_class.new # => #<Rogue ...>
In your example, this would look like:
def fight(name_of_monster_to_fight)
monster_class = Object.const_get(name_of_monster_to_fight)
m = monster_class.new
# ... more code
rescue NameError # This is the error thrown when the class doesn't exist
puts "error 503"
end
I know I'm being an idiot here, but I can't think of how this is done. I am creating an app with certain interests and am using a a Wikipedia scrape set up using Nokogiri. I have two inputs: Title and Wikipedia, but want to fill Summary and Content in the data model using the scrape. I want to use the Wikipedia attribute as a variable in a url within a method, but keep getting the error dynamic constant assignment PAGE_URL = "http://en.wikipedia.org/w/i....
I thought that the methods should go in the model, with reference to them in the Create definition under the controller, but this doesn't seem to work.
EDIT
I've just tried taking the constants out of the methods as suggested, but I am still getting a dynamic constant assignment error. My model currently looks like this:
PAGE_URL1 = "http://en.wikipedia.org/w/index.php?title="
PAGE_URL2 = "&printable=yes"
def get_PAGE_URL
PAGE_URL = PAGE_URL1 + self.wikipedia + PAGE_URL2
end
def get_page
page = Nokogiri::HTML(open(PAGE_URL))
end
def get_summary
get_PAGE_URL
self.summary = page.css("p")[0].text
end
def get_full_page
get_PAGE_URL
puts page.css('div#content.mw-body div#bodyContent div#mw-content-text.mw-content-ltr p').each do |p|
self.content = puts p.text
end
end
Constants can't go inside of methods, they must be defined inside of the class' direct scope.
Edit:
For example:
class WikiScraper
PAGE_URL = "http://www.wikipedia.org/"
def scrape
page_num = '5'
my_url = PAGE_URL + page_num
end
end
I am receiving the following error when running my below ruby script:
s3parse.rb:12:in `block in <class:AccountLog>': undefined method `extract_account_id' for AccountLog:Class (NoMethodError)
I dont think it should be a class method, is there a reason its not taking my method into account?
class AccountLog
attr_accessor :bytes, :account_id, :date
def extract_account_id(line)
line.match(%r{accounts/(\d+)}).captures.join.to_i
end
s3log = File.open('vidcoder.txt').each do |line|
account_log = AccountLog.new
account_log.date = line.match(%r{\[[^:]*}).to_s.delete"[" #need to finish this regex to make it work
account_log.account_id = extract_account_id(line)
account_log.bytes = line.match(%r{^.*\s+HTTP.*\s+-\s+(\d+)\s+}).captures.join.to_i
puts "\n"
puts "The api request on #{account_log.date} was fromm account number #{account_log.account_id} and the bytes were #{account_log.bytes}"
end
end
def extract_account_id will define an instance method.
In the way you call it, you need a class method instead.
Define it like this:
def self.extract_account_id(line)
or, as you already have an AccountLog instance, use it to call extract_account_id:
account_log.account_id = account_log.extract_account_id(line)
Please note that with second way you do not need to alter method definition, just call extract_account_id via account_log instance.
And i guess you would want to put s3log = File... outside class definition.
Or use a constant instead: S3log = ...
Then you'll can access it as AccountLog::S3log
Is there any reason you don't think it should be a class method? You are using it in the context of a class method and that's why it it's saying no such method for class AccountLog.
If you name your method as self.extract_account_id(line) I'm sure it will work.
From what you are trying to do I think this is what you are looking for?
class AccountLog
attr_accessor :bytes, :account_id, :date
def self.extract_account_id(line)
line.match(%r{accounts/(\d+)}).captures.join.to_i
end
end
s3log = File.open('vidcoder.txt').each do |line|
account_log = AccountLog.new
account_log.date = line.match(%r{\[[^:]*}).to_s.delete"[" #need to finish this regex to make it work
account_log.account_id = extract_account_id(line)
account_log.bytes = line.match(%r{^.*\s+HTTP.*\s+-\s+(\d+)\s+}).captures.join.to_i
puts "\n"
puts "The api request on #{account_log.date} was fromm account number #{account_log.account_id} and the bytes were #{account_log.bytes}"
end
While you could take the class method approach, there seems to be a little more going on.
You should put the extraction logic in a method in itself rather than let it hangout in your class. Then outside of the class, have an instance of AccountLog where you can call on the methods for log and account id extraction. At that point you can do something with those values.
Class method or not is a detail we can explore after the class is a bit more clean I think.