I have a couple Nagios scripts which inherit a common NagiosCheck class. Since every check has slightly different getopts options I thought it'd be the best to generate the available options via a NagiosCheck class method. But I'm stuck...
This is how I call the method:
class CheckFoobar < NagiosCheck
...
end
check = CheckFoobar.new
check.generate_options(
['-H', '--hostname', GetoptLong::REQUIRED_ARGUMENT],
['-P', '--port', GetoptLong::REQUIRED_ARGUMENT],
['-u', '--url', GetoptLong::REQUIRED_ARGUMENT])
The method itself:
class NagiosCheck
...
def generate_options (*args)
options = []
args.each do |arg|
options << arg
end
parser = GetoptLong.new
options.each {|arg| parser.set_options(arg)}
end
end
Then parser only stores the last item:
p parser # => #<GetoptLong:0x00000000e17dc8 #ordering=1, #canonical_names={"-u"=>"-u", "--url"=>"-u"}, #argument_flags={"-u"=>1, "--url"=>1}, #quiet=false, #status=0, #error=nil, #error_message=nil, #rest_singles="", #non_option_arguments=[]>
Do you have any advice for me how to get parser to store all arguments?
Regards,
Mike
... First question here on stackoverflow. Please bear with me if I did something wrong and let me know so that I'm able to adapt.
The generate_options method is too complex. Getoptlong.new takes an array of arrays as argument.
class NagiosCheck
def generate_options (*args)
GetoptLong.new(*args)
end
end
Related
I have recently started using Rubocop to "standardise" my code, and it has helped me optimise a lot of my code, as well as help me learn a lot of Ruby "tricks". I understand that I should use my own judgement and disable Cops where necessary, but I have found myself quite stuck with the below code:
def index
if params[:filters].present?
if params[:filters][:deleted].blank? || params[:filters][:deleted] == "false"
# if owned is true, then we don't need to filter by admin
params[:filters][:admin] = nil if params[:filters][:admin].present? && params[:filters][:owned] == "true"
# if admin is true, then must not filter by owned if false
params[:filters][:owned] = nil if params[:filters][:owned].present? && params[:filters][:admin] == "false"
companies_list =
case params[:filters][:admin]&.to_b
when true
current_user.admin_companies
when false
current_user.non_admin_companies
end
if params[:filters][:owned].present?
companies_list ||= current_user.companies
if params[:filters][:owned].to_b
companies_list = companies_list.where(owner: current_user)
else
companies_list = companies_list.where.not(owner: current_user)
end
end
else
# Filters for deleted companies
companies_list = {}
end
end
companies_list ||= current_user.companies
response = { data: companies_list.alphabetical.as_json(current_user: current_user) }
json_response(response)
end
Among others, the error that I'm getting is the following:
C: Metrics/AbcSize: Assignment Branch Condition size for index is too high. [<13, 57, 16> 60.61/15]
I understand the maths behind it, but I don't know how to simplify this code to achieve the same result.
Could someone please give me some guidance on this?
Thanks in advance.
Well first and foremost, is this code fully tested, including all the myriad conditions? It's so complex that refactoring will surely be disastrous unless the test suite is rigorous. So, write a comprehensive test suite if you don't already have one. If there's already a test suite, make sure it tests all the conditions.
Second, apply the "fat model skinny controller" paradigm. So move all the complexity into a model, let's call it CompanyFilter
def index
companies_list = CompanyFilter.new(current_user, params).list
response = { data: companies_list.alphabetical.as_json(current_user: current_user) }
json_response(response)
end
and move all those if/then/else statements into the CompanyFilter#list method
tests still pass? great, you'll still get the Rubocop warnings, but related to the CompanyFilter class.
Now you need to untangle all the conditions. It's a bit hard for me to understand what's going on, but it looks as if it should be reducible to a single case statement, with 5 possible outcomes. So the CompanyFilter class might look something like this:
class CompanyFilter
attr_accessors :current_user, :params
def initialize(current_user, params)
#current_user = current_user
#params = params
end
def list
case
when no_filter_specified
{}
when user_is_admin
#current_user.admin_companies
when user_is_owned
# etc
when # other condition
# etc
end
end
private
def no_filter_specified
#params[:filter].blank?
end
def user_is_admin
# returns boolean based on params hash
end
def user_is_owned
# returns boolean based on params hash
end
end
tests still passing? perfect! [Edit] Now you can move most of your controller tests into a model test for the CompanyFilter class.
Finally I would define all the different companies_list queries as scopes on the Company model, e.g.
class Company < ApplicationRecord
# some examples, I don't know what's appropriate in this app
scope :for_user, ->(user){ where("...") }
scope :administered_by, ->(user){ where("...") }
end
When composing database scopes ActiveRecord::SpawnMethods#merge is your friend.
Post.where(title: 'How to use .merge')
.merge(Post.where(published: true))
While it doesn't look like much it lets you programatically compose scopes without overelying on mutating assignment and if/else trees. You can for example compose an array of conditions and merge them together into a single ActiveRecord::Relation object with Array#reduce:
[Post.where(title: 'foo'), Post.where(author: 'bar')].reduce(&:merge)
# => SELECT "posts".* FROM "posts" WHERE "posts"."title" = $1 AND "posts"."author" = $2 LIMIT $3
So lets combine that with a skinny controllers approach where you handle filtering in a seperate object:
class ApplicationFilter
include ActiveModel::Attributes
include ActiveModel::AttributeAssignment
attr_accessor :user
def initialize(**attributes)
super()
assign_attributes(attributes)
end
# A convenience method to both instanciate and apply the filters
def self.call(user, params, scope: model_class.all)
return scope unless params[:filters].present?
scope.merge(
new(
permit_params(params).merge(user: user)
).to_scope
)
end
def to_scope
filters.map { |filter| apply_filter(filter) }
.compact
.select {|f| f.respond_to?(:merge) }
.reduce(&:merge)
end
private
# calls a filter_by_foo method if present or
# defaults to where(key => value)
def apply_filter(attribute)
if respond_to? "filter_by_#{attribute}"
send("filter_by_#{attribute}")
else
self.class.model_class.where(
attribute => send(attribute)
)
end
end
# Convention over Configuration is sexy.
def self.model_class
name.chomp("Filter").constantize
end
# filters the incoming params hash based on the attributes of this filter class
def self.permit_params
params.permit(filters).reject{ |k,v| v.blank? }
end
# provided for modularity
def self.filters
attribute_names
end
end
This uses some of the goodness provided by Rails to setup objects with attributes that will dynamically handle filtering attributes. It looks at the list of attributes you have declared and then slices those off the params and applies a method for that filter if present.
We can then write a concrete implementation:
class CompanyFilter < ApplicationFilter
attribute :admin, :boolean, default: false
attribute :owned, :boolean
private
def filter_by_admin
if admin
user.admin_companies
else
user.non_admin_companies
end
end
# this should be refactored to use an assocation on User
def filter_by_owned
case owned
when nil
nil
when true
Company.where(owner: user)
when false
Company.where.not(owner: user)
end
end
end
And you can call it with:
# scope is optional
#companies = CompanyFilter.call(current_user, params), scope: current_user.companies)
I have seen a lot of examples of Ruby classes that utilize the Hash method of delete and I am not sure what the advantage of using it would be.
Example:
class Example
def initialize(default_params = {})
#foo = default_params.delete(:bar)
end
end
Any insight would be extremely helpful! Thanks!
Hash#delete is useful in the following situation:
def method(options)
if options.delete(:condition)
# Do something if options[:condition] is true
else
# Otherwise do something else
end
# Now options doesn't have the :conditions key-value pair.
another_method_that_doesnt_use_the_condition(options)
end
I'm unsure if the specific example you pulled should be using Hash#delete.
I have just written my first terminal application in ruby. I use OptionParser to parse the options and their arguments. However I want to create commands. For example:
git add .
In the above line, add is the command which cannot occur anywhere else than immediately after the application. How do I create these.
I will appreciate if anyone could point me in the right direction. However, please do not reference any gems such as Commander. I already know about these. I want to understand how it is done.
The OptionParser's parse! takes an array of arguments. By default, it will take ARGV, but you can override this behaviour like so:
Basic Approach
def build_option_parser(command)
# depending on `command`, build your parser
OptionParser.new do |opt|
# ...
end
end
args = ARGV
command = args.shift # pick and remove the first option, do some validation...
#options = build_option_parser(command).parse!(args) # parse the rest of it
Advanced Approach
Instead of a build_option_parser method with a huge case-statement, consider an OO approach:
class AddCommand
attr_reader :options
def initialize(args)
#options = {}
#parser = OptionParser.new #...
#parser.parse(args)
end
end
class MyOptionParser
def initialize(command, args)
#parser = {
'add' => AddCommand,
'...' => DotsCommand
}[command.to_s].new(args)
end
def options
#parser.options
end
end
Alternatives
For sure, there exist tons of Rubygems (well, 20 in that list), which will take care of your problem. I'd like to mention Thor which powers, e.g. the rails command line tool.
You can retrieve the command with Array#shift prior invoking OptionParser.
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.
I am using DataMapper for Database access. My goal is to send the models to an webservice as read-only object. This is my current try:
class User
include DataMapper::Resource
def to_yaml(opts = {})
mini_me = OpenStruct.new
instance_variables.each do |var|
next if /^#_/ =~ var.to_s
mini_me.send("#{var.to_s.gsub(/^#/, '')}=", instance_variable_get(var))
end
mini_me.to_yaml(opts)
end
....
end
YAML::ENGINE.yamler = 'psych'
u = User.get("hulk")
p u.to_yaml
# => "--- !ruby/object:OpenStruct\ntable:\n :uid: hulk\n :uidNumber: 1000\n :gidNumber: 1001\n :email: hulk#example.com\n :dn: uid=hulk,ou=People,o=example\n :name: Hulk\n :displayName: Hulk\n :description: Hulk\n :homeDirectory: /home/hulk\n :accountFlags: ! '[U ]'\n :sambaSID: S-1-5-21-......\nmodifiable: true\n"
p [ u ].to_yaml # TypeError: can't dump anonymous class Class
Any ideas how to make this work and get rid of the exception?
Thanks,
krissi
Using to_yaml is deprecated in Psych, and from my testing it seems to be actually broken in cases like this.
When you call to_yaml directly on your object, your method gets called and you get the result you expect. When you call it on the array containing your object, Psych serializes it but doesn’t correctly handle your to_yaml method, and ends up falling back onto the default serialization. In your case this results in an attempt to serialize an anonymous Class which causes the error.
To fix this, you should use the encode_with method instead. If it’s important that the serialized form is tagged as an OpenStruct object in the generated yaml you can use the represent_object (that first nil parameter doesn’t seem to be used):
def encode_with(coder)
mini_me = OpenStruct.new
instance_variables.each do |var|
next if /^#_/ =~ var.to_s
mini_me.send("#{var.to_s.gsub(/^#/, '')}=", instance_variable_get(var))
end
coder.represent_object(nil, mini_me)
end
If you were just using OpenStruct for convenience, an alternative could be something like:
def encode_with(coder)
instance_variables.each do |var|
next if /^#_/ =~ var.to_s
coder[var.to_s.gsub(/^#/, '')]= instance_variable_get(var)
end
end
Note that Datamapper has its own serializer plugin that provides yaml serialization for models, it might be worth looking into.