I'm currently trying to tidy up a method which displays all items in my S3 bucket, and as I already have the Bucket Address defined in my script I thought it best to reference the method rather than put in the address into my listing method. However, when I do so I receive the error
ArgumentError: :bucket must not be blank
I feel like I'm missing something obvious, surely I don't have to attach the whole addresss into my params? Attached below is the relevant(?) pieces of code.
def bucket_name
'textract-console-eu-central-xxxxxxxxx'
end
def s3_resource
#s3_resource ||= ::Aws::S3::Resource.new(client: s3_client)
end
the code in question
def list_bucket_objects(s3_resource, bucket_name:'')
puts s3_resource.bucket(bucket_name).objects(prefix:'', delimiter: '').collect(&:key)
end
end
You override the bucket_name here:
def list_bucket_objects(s3_resource, bucket_name:'')
^
Remove the second parameter and you should be good to go.
Related
This is a fake banking app:
class Bank
private def initialize
$login = Hash.new
puts "Welcome to HEIDI BANK!"
end
def add(keyVal)
keyVal.each do |key, value|
$login[key] = value
end
end
def NewUser
puts "What is the name of the user you would like to add?"
user = gets.chomp
puts "What is the password you would add?"
pass = gets.chomp
passsym = pass.to_sym
$login.add(user => passsym)
end
end
you_bank = Bank.new
you_bank.NewUser
When I attempt to run it, I get:
Welcome to HEIDI BANK!
What is the name of the user you would like to add?
12
What is the password you would add?
13
then an error is raised:
in `NewUser': undefined method `add' for {}:Hash(NoMethodError)
How would I fix this error? It seems I might have to figure out how to call Bank.add or something. Do hashes have an add function built in, like with samp_array.push for arrays?
You defined add as an instance method of Bank, but you are calling it on $login, which is an instance of Hash. Call it on the instance of Bank itself, which can be omitted:
def NewUser
...
add(user => passsym)
end
I already provided the answer in the comments but I wanted to make a longer form answer to help you out. It appears that you're a young programmer and new to Ruby so I would like to help you adopt healthy habits. Accordingly, I have refactored your code and included comments explaining the changes with links to resources that you can read to help understand why the changes were made.
These are mostly minor issues but they're important when writing any kind of production code or when writing code that others may have to read or use in the future.
# Allows the use of STDIN.noecho which will not echo text input back to the console:
# https://stackoverflow.com/a/29334534/3784008
require 'io/console'
# Use two spaces of indentation for Ruby, not tabs and not 4 spaces:
# https://github.com/rubocop-hq/ruby-style-guide#source-code-layout
class Bank
# The initialize method is not a private method:
# https://stackoverflow.com/q/1567400/3784008
def initialize
# Use single quotes for non-interpolated strings
# https://github.com/rubocop-hq/ruby-style-guide#strings
puts 'Welcome to HEIDI BANK!'
# Don't instantiate the `login` variable here; it should be lazily instantiated:
# http://blog.jayfields.com/2007/07/ruby-lazily-initialized-attributes.html
end
# Use snake_case for method names
# https://github.com/rubocop-hq/ruby-style-guide#naming
def new_user
puts 'What is the name of the user you would like to add?'
user = gets.chomp
puts 'What is the password you would add?'
# Suppress local echo of the password as it is typed
# https://stackoverflow.com/a/29334534/3784008
pass = STDIN.noecho(&:gets).chomp
# Do not call .to_sym on pass; if pass == an Integer then it will raise an exception,
# e.g., 1.to_sym => NoMethodError: undefined method `to_sym' for 1:Integer
{ user => pass }
end
end
Then you run it like you were doing before:
you_bank = Bank.new
Welcome to HEIDI BANK!
=> #<Bank:0x00007f8cc9086710>
you_bank.new_user
What is the name of the user you would like to add?
foo
What is the password you would add?
=> {"foo"=>"bar"}
Two other notes on your original code:
Don't use global variables (variable name preceded with a $). There is more explanation at this answer. If you end up needing a variable that is accessible within the instance of the class you should use an instance variable.
Write DRY code. There's no need for the add(keyVal) method because it's implemented already in Hash by merge. Try translating the issue you want to resolve into something you can search for, in this case you want to "add to hash in ruby" and the first Google result for that query is this answer that details how to do that.
I hope this helps you out.
Update
Below you asked "what is lazy instantiation?" The short answer is: don't assign variables until they need to be used. For example:
# Bad; don't do this
class Foo
def initialize
# This variable is instantiated when calling `Foo.new`,
# before it needs to be used, and so takes up memory right
# away vs. only once it's needed
#variable_used_by_example_method = 'foobar'
end
def example_method
puts #variable_used_by_example_method
end
end
# Better; okay to do this
class Foo
def initialize
end
def example_method
# This variable is lazily instantiated, that is, it is not
# instantiated until `Foo.new.example_method` is called
#variable_used_by_example_method = 'foobar'
puts #variable_used_by_example_method
end
end
For your other question about comparing usernames and passwords against what users type in, I recommend you think through the problem and if you still are unsure then post a new question. The question you've asked isn't clear enough for me to give you a good answer. Right now you're experimenting with the code to figure out how everything works, and when you're experimenting and learning it's okay to do things that don't squarely fit into object-oriented programming design patterns. But any answer I give you based on what you've told me so far would either go against those patterns, or would be too advanced. (e.g., use a database and associated models in a framework like Rails)
I wouldn't do the first because that would be bad advice, and I wouldn't do the second because you should have a firmer grasp of Ruby and programming first. So my recommendation is for you to think these through:
What is the plain-English step-by-step explanation of your overall goal?
How can that explanation be described in terms of object-oriented logic?
What code can you write to encapsulate that logic?
What are the gaps between your ability to describe the logic and your ability to write code for that logic?
Then you can begin to ask specific questions to fill in those gaps.
The need here is to read a json file and to make the variables which is done from one class and use them with in another class. What I have so far is
helper.rb
class MAGEINSTALLER_Helper
#note nonrelated items removed
require 'fileutils'
#REFACTOR THIS LATER
def load_settings()
require 'json'
file = File.open("scripts/installer_settings.json", "rb")
contents = file.read
file.close
#note this should be changed for a better content check.. ie:valid json
#so it's a hack for now
if contents.length > 5
begin
parsed = JSON.parse(contents)
rescue SystemCallError
puts "must redo the settings file"
else
puts parsed['bs_mode']
parsed.each do |key, value|
puts "#{key}=>#{value}"
instance_variable_set("#" + key, value) #better way?
end
end
else
puts "must redo the settings file"
end
end
#a method to provide feedback simply
def download(from,to)
puts "completed download for #{from}\n"
end
end
Which is called in a file of Pre_start.rb
class Pre_start
#note nonrelated items removed
def initialize(params=nil)
puts 'World'
mi_h = MAGEINSTALLER_Helper.new
mi_h.load_settings()
bs_MAGEversion=instance_variable_get("#bs_MAGEversion") #doesn't seem to work
file="www/depo/newfile-#{bs_MAGEversion}.tar.gz"
if !File.exist?(file)
mi_h.download("http://www.dom.com/#{bs_MAGEversion}/file-#{bs_MAGEversion}.tar.gz",file)
else
puts "mage package exists"
end
end
end
the josn file is valid json and is a simple object (note there is more just showing the relevant)
{
"bs_mode":"lite",
"bs_MAGEversion":"1.8.0.0"
}
The reason I need to have a json settings file is that I will need to pull settings from a bash script and later a php script. This file is the common thread that is used to pass settings each share and need to match.
Right now I end up with an empty string for the value.
The instance_variable_setis creating the variable inside MAGEINSTALLER_Helper class. That's the reason why you can't access these variables.
You can refactor it into a module, like this:
require 'fileutils'
require 'json'
module MAGEINSTALLER_Helper
#note nonrelated items removed
#REFACTOR THIS LATER
def load_settings()
content = begin
JSON.load_file('scripts/installer_settings.json')
rescue
puts 'must redo the settings file'
{} # return an empty Hash object
end
parsed.each {|key, value| instance_variable_set("##{key}", value)}
end
#a method to provide feedback simply
def download(from,to)
puts "completed download for #{from}\n"
end
end
class PreStart
include MAGEINSTALLER_Helper
#note nonrelated items removed
def initialize(params=nil)
puts 'World'
load_settings # The method is available inside the class
file="www/depo/newfile-#{#bs_MAGEversion}.tar.gz"
if !File.exist?(file)
download("http://www.dom.com/#{#bs_MAGEversion}/file-#{#bs_MAGEversion}.tar.gz",file)
else
puts "mage package exists"
end
end
end
I refactored a little bit to more Rubish style.
On this line:
bs_MAGEversion=instance_variable_get("#bs_MAGEversion") #doesn't seem to work
instance_variable_get isn't retrieving from the mi_h Object, which is where your value is stored. The way you've used it, that line is equivalent to:
bs_MAGEversion=#bs_MAGEversion
Changing it to mi_h.instance_variable_get would work. It would also be painfully ugly ruby. But I sense that's not quite what you're after. If I read you correctly, you want this line:
mi_h.load_settings()
to populate #bs_MAGEversion and #bs_mode in your Pre_start object. Ruby doesn't quite work that way. The closest thing to what you're looking for here would probably be a mixin, as described here:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_modules.html
We do something similar to this all the time in code at work. The problem, and solution, is proper use of variables and scoping in the main level of your code. We use YAML, you're using JSON, but the idea is the same.
Typically we define a constant, like CONFIG, which we load the YAML into, in our main code, and which is then available in all the code we require. For you, using JSON instead:
require 'json'
require_relative 'helper'
CONFIG = JSON.load_file('path/to/json')
At this point CONFIG would be available to the top-level code and in "helper.rb" code.
As an alternate way of doing it, just load your JSON in either file. The load-time is negligible and it'll still be the same data.
Since the JSON data should be static for the run-time of the program, it's OK to use it in a CONSTANT. Storing it in an instance variable only makes sense if the data would vary from instance to instance of the code, which makes no sense when you're loading data from a JSON or YAML-type file.
Also, notice that I'm using a method from the JSON class. Don't go through the rigamarole you're using to try to copy the JSON into the instance variable.
Stripping your code down as an example:
require 'fileutils'
require 'json'
CONTENTS = JSON.load_file('scripts/installer_settings.json')
class MAGEINSTALLER_Helper
def download(from,to)
puts "completed download for #{from}\n"
end
end
class Pre_start
def initialize(params=nil)
file = "www/depo/newfile-#{ CONFIG['bs_MAGEversion'] }.tar.gz"
if !File.exist?(file)
mi_h.download("http://www.dom.com/#{ CONFIG['bs_MAGEversion'] }/file-#{ CONFIG['bs_MAGEversion'] }.tar.gz", file)
else
puts "mage package exists"
end
end
end
CONFIG can be initialized/loaded in either file, just do it from the top-level before you need to access the contents.
Remember, Ruby starts executing it at the top of the first file and reads downward. Code that is outside of def, class and module blocks gets executed as it's encountered, so the CONFIG initialization will happen as soon as Ruby sees that code. If that happens before you start calling your methods and creating instances of classes then your code will be happy.
As part of an online Ruby tutorial, I must create a text-based game. One requirement is that I use require to pull in another file. I've done that as well as include the module that holds a method. However, I cannot produce the result I want. Here's my file with the module:
module Inventory
def Inventory.inventory(item)
items = Array.new
if item == "show"
items.inspect
else
items << item
end
end
end
I want the parameter (item) to be added to the array items as a string that can be inspected when I pass the "show" argument to it.
So for example, I want to add a 'bat' to the inventory so I call Inventory.inventory("bat"). Later I'd like to add other things. But when I call Inventory.inventory("show") it doesn't show anything.
I've spent days looking through many other tutorials and hundreds of questions here but still can't get it work. I'm probably not understanding something really fundamental so please be gracious to me as I'm still learning.
Is it the way I'm adding to an array? The way I'm trying to get it to show? Or do I not understand how to use methods and arguments?
you can Dylan's answer if you want to go with instance approach or you can use class variables.
The problem with your code is that you initialize items local variable every time you call inventory.
Here is a version that will persist items in a class variable:
module Inventory
def Inventory.inventory(item)
##items ||= Array.new
if item == "show"
##items.inspect
else
##items << item
end
end
end
Inventory.inventory 1
Inventory.inventory 2
p Inventory.inventory 'show'
this is producing
"[1, 2]"
This would make a lot more sense as a class. This way, you can store the items in an instance variable that will persist during multiple calls to add, show, etc. You can of course put this class into a separate file and still include it.
class Inventory
def initialize
#items = []
end
def add(item)
#items << item
end
def show
#items.inspect
end
end
# To use the class:
inventory = Inventory.new
inventory.add('bat')
inventory.show
# => ["bat"]
The issue is that your items array is being recreated every time this method is called, so there is no persistence between method calls for what is passed into the array. Dylan Markow's answer shows how you can use instance variables to persist values between method calls.
Let me preface by stating I'm a "new" programmer - an IT guy trying his hand at his first "real" problem after working through various tutorials.
So - here is what I'm trying to do. I'm watching a directory for a .csv file - it will be in this format: 999999_888_filename.csv
I want to return each part of the "_" filename as a variable to pass on to another program/script for some other task. I have come up w/ the following code:
require 'rubygems'
require 'fssm'
class Watcher
def start
monitor = FSSM::Monitor.new(:directories => true)
monitor.path('/data/testing/uploads') do |path|
path.update do |base, relative, ftype|
output(relative)
end
path.create do |base, relative, ftype|
output(relative)
end
path.delete { |base, relative, ftype| puts "DELETED #{relative} (#{ftype})" }
end
monitor.run
end
def output(relative)
puts "#{relative} added"
values = relative.split('_',)
sitenum = values[0]
numrecs = values[1]
filename = values[2]
puts sitenum
end
end
My first "puts" gives me the full filename (it's just there to show me the script is working), and the second puts returns the 'sitenum'. I want to be able to access this "outside" of this output method. I have this file (named watcher.rb) in a libs/ folder and I have a second file in the project root called 'monitor.rb' which contains simply:
require './lib/watcher'
watcher = Watcher.new
watcher.start
And I can't figure out how to access my 'sitenum', 'numrecs' and 'filename' from this file. I'm not sure if it needs to be a variable, instance variable or what. I've played around w/ attr_accessible and other things, and nothing works. I decided to ask here since I've been spinning my wheels for a couple of things, and I'm starting to confuse myself by searching on my own.
Thanks in advance for any help or advice you may have.
At the top of the Watcher class, you're going to want to define three attr_accessor declarations, which give the behavior you want. (attr_reader if you're only reading, attr_writer if you're only writing, attr_accessor if both.)
class Watcher
attr_accessor :sitenum, :numrecs, :filename
...
# later on, use # for class variables
...
#sitenum = 5
...
end
Now you should have no problem with watcher.sitenum etc. Here's an example.
EDIT: Some typos.
In addition to Jordan Scales' answer, these variable should initialized
class Watcher
attr_accessor :sitenum, :numrecs, :filename
def initialize
#sitenum = 'default value'
#numrecs = 'default value'
#filename = 'default value'
end
...
end
Otherwise you'll get uninformative value nil
I want to eliminate "=" sign for a particular reason. It might looks like this:
cat_that_has_name("Kelly").as(:kelly)
kelly.do_something
The "as" method here is used to generate a method "kelly" that reference my cat. Could anyone help me with this?
Any suggestions will be appreciated.
Update:
Jorg was right, I've add a simple test to demonstrate my intention:
require "test/unit"
class AsTest < Test::Unit::TestCase
def setup
#cats = ["Kelly", "Tommy"]
end
def teardown
end
def test_as
kelly1 = get_cat("Kelly")
get_cat("Kelly").as(:kelly2)
assert_equal(kelly1.object_id, kelly2.object_id)
end
private
def get_cat(name)
#cats.each do |cat|
if cat.to_s==name
return cat
end
end
return nil
end
end
It's kind of hard to figure out what you actually want. If you want some sensible answers, you will have to provide a complete code example of what you want to achieve (for example, the code you posted is missing definitions for the cat_that_has_name and so_something methods). You will also need to post a complete specification of what exactly you expect the as method to do, with usage examples and ideally also with a testsuite. After all, how do we know if our answer is correct if you haven't defined what "correct" means?
The best I could decipher from your cryptic question is something like this:
class Object
def as(name)
s = self
Object.send(:define_method, name) { s }
Object.send(:private, name)
end
end
But there is no way of knowing whether this works, because if I try to run your code example, I get a NoMethodError for cat_that_has_name and another NoMethodError for so_something.
Note also that your question is self-inconsistent: in your subject line you ask about a method to replace = (i.e. creating variables) but in your question you talk about creating methods, which would mean that you are looking for a replacement for def and not for =. Again, it would be much easier to answer correctly if there were a testsuite.