How can I extract a Ruby `instance_eval` invocation into a method? - ruby

I have this Ruby code for a Padrino application:
module Filters
def self.authorize_admin
proc { halt(401) unless current_user.admin? }
end
end
App.controllers :secrets do
before :show, &Filters.authorize_admin
# ...
end
When the secrets controller receives a request on the show route, it will run the authorize_admin filter.
If I want this rule to apply to every route instead, I might write this:
before { instance_eval &Filters.authorize_admin }
I'd like to extract this to a method in Filters instead, so that I can just write:
before { Filters.only_administrators }
What's the right way to do that?

I wound up doing this:
module Filters
def self.authorize_admin
proc { halt(401) unless current_user.admin? }
end
def self.filter(controller, filter)
filter_method = method(filter.to_sym)
controller.instance_eval &(filter_method.call)
end
end
and you now invoke it like:
Filters.filter(self, :authorize_admin)

Related

Hanami parameters whitelisting

Following the hanami docs, in order to block a admin parameter inside an action, I can use the following configuration:
params do
required(:email).filled
required(:address).schema do
required(:country).filled
end
end
def call(params)
puts params[:email] # => "alice#example.org"
puts params[:address][:country] # => "Italy"
puts params[:admin] # => nil
end
But this does not work for nested parameters, i.e.:
params do
required(:email).filled
required(:address).schema do
required(:country).filled
end
end
def call(params)
puts params[:email] # => "alice#example.org"
puts params[:address] # => { country: "Italy", admin: true }
puts params[:address][:admin] # => true
end
I was able to solve this by using select to filter out the undesirable parameters with a private method, but this does not seems like the Hanami way. What would be the proper way to do this whitelisting of nested parameters?
I have never had this issue when using Hanami Validations. Within the app directory there should be a validations folder which should have the same directory structure as your controllers, views, templates etc. Your validation file should look something like this:
# apps/web/validations/users/create.rb
module Web
module Validations
module Users
class Create < Web::Action::Params
predicates Web::Validations::CommonPredicates
validations do
required(:email).filled
required(:address).schema do
required(:country).filled
end
end
end
end
end
end
And then your controller should set the params to be filtered through the validation:
module Web
module Controllers
module Users
class Create
include Web::Action
params Web::Validations::Users::Create
def call(params); end
end
end
end
end

How do I access a variable inside the method I'm calling in a block I'm passing to it?

I'm writing a wrapper for an XML API using Nokogiri to build the XML for submission.
In order to keep my code DRY, I'm using custom blocks for the first time and just getting to grips with how to pass variables back and forth and how that works.
What I'm doing at the moment is this:
# Generic action
def action(xml, action_title, test=false)
xml.request do
xml.login do
xml.username("my_user")
xml.password("my_pass")
end
xml.action(action_title)
xml.params do
yield
end
end
end
# Specific action
def get_users(city = "", gender = "")
build = Nokogiri::XML::Builder.new do |xml|
action(xml, "getusers") do
xml.city(city) unless city.blank?
xml.gender(gender) unless gender.blank?
end
end
do_stuff_to(build)
end
Ideally, I'd like to the specific action method to look like this:
def get_users(city = "", gender = "")
action("getusers") do |xml|
xml.city(city) unless city.blank?
xml.gender(gender) unless gender.blank?
end
end
In doing so, I'd want the other logic currently in the specific action method to be moved to the generic action method with the generic action method returning the results of do_stuff_to(build).
What I'm struggling with is how to pass the xml object from action() back to get_users(). What should action() look like in order to achieve this?
Turns out this was quite simple. The action method needs to be changed so it looks like this:
def action(action_title)
build = Nokogiri::XML::Builder.new do |xml|
xml.request do
xml.login do
xml.username("my_user")
xml.password("my_pass")
end
xml.action(action_title)
xml.params do
yield xml
end
end
end
do_stuff_to(build)
end
That meant the specific action method could be called like this to the same effect:
def get_users(city = "", gender = "")
action("getusers") do |xml|
xml.city(city) unless city.blank?
xml.gender(gender) unless gender.blank?
end
end

Test helpers with RSpec in Padrino (Sinatra)

I'm trying to test a helper in a Padrino (Sinatra) app. My helper method is itself calling Padrino core helper methods but they are undefined. The error appears only in RSpec, while the app works fine. So the way I'm including my helper in RSpec makes it loose "Padrino scope" but I don't know how to bring Padrino helper's scope properly in my RSpec environment.
My helper:
module AdminHelper
Sort = Struct.new(:column, :order)
def sort_link(model, column)
order = sorted_by_this?(column) ? 'desc' : 'asc'
link_to mat(model, column), url(:pages, :index, sort: column, order: order)
end
def sorted_by_this?(column)
column.to_s == #sort.column && #sort.order == 'asc'
end
end
Lenstroy::Admin.helpers AdminHelper
My spec:
describe AdminHelper do
before(:all) do
class AdminHelperClass
include AdminHelper
end
end
subject(:helper) { AdminHelperClass.new }
describe '#sort_link' do
context "with :pages and :title parameters" do
before do
sort = AdminHelperClass::Sort.new('title', 'asc')
helper.instance_variable_set('#sort', sort)
end
subject { helper.sort_link(:pages, :title) }
it { should match(/<a href=([^ ]+)pages/) }
end
end
end
Results in error:
1) AdminHelper#sort_link with :pages and :title parameters
Failure/Error: subject { helper.sort_link(:pages, :title) }
NoMethodError:
undefined method `mat' for #<AdminHelperClass:0x007f1d951dc4a0>
Including a helper where mat is defined doesn't work, as one method is dependent on another helper and it goes on and on...
Update
In my spec helper I have:
def app(app = nil, &blk)
#app ||= block_given? ? app.instance_eval(&blk) : app
#app ||= Lenstroy::Admin
#app.register Padrino::Helpers
#app.register Padrino::Rendering
#app
end
in my spec I have:
it "returns link to resource with sort parameters" do
app do
get '/' do
sort_link(:pages, :title)
end
end
get "/"
last_response.body.should =~ /<a href=([^ >]+)pages/
end
And now tests fail, last_response.body is ''.
Method #mat is defined in Padrino::Admin::Helpers::ViewHelpers. You can do
class AdminHelperClass
include Padrino::Admin::Helpers::ViewHelpers
include AdminHelper
end
Update:
If your methods are really dependent on all these routes and helpers you should consider doing full mockup of your app like this:
def mock_app(base=Padrino::Application, &block)
#app = Sinatra.new(base, &block)
#app.register Padrino::Helpers
#app.register Padrino::Rendering
# register other things
end
def app
Rack::Lint.new(#app)
end
mock_app do
get '/' do
sort_link(my_model, my_column)
end
end
get "/"
assert_equal "some test text", body
Here's how it's done in padrino-admin: https://github.com/padrino/padrino-framework/blob/master/padrino-admin/test/test_admin_application.rb
I was having the same problem (and getting very frustrated tracking down the modules and including them). So far, I've got my specs working by:
1) Explicitly defining my module (as explained in how to use padrino helper methods in rspec)
module MyHelper
...
end
MyApp::App.helpers MyHelper
2) Automatically including helpers at the top of my spec. (Right now I only have one helper spec, but in the future I might try to move this into spec_helper.rb.)
describe MyHelper do
let(:helpers) { Class.new }
before { MyApp::App.included_modules.each { |m| helpers.extend m } }
subject { helpers }
it 'blah' do
expect(subject.helper_method).to eq 'foo'
end
end

Sinatra, DRY and scoping

I'm looking for ways to DRY my Sinatra app and have run into some scoping issues -- in particular, helpers and Sinatra functions are not available inside my handlers. Can someone please tell me if there's a way to fix this code and more importantly, what is going on?
Thank you.
require 'sinatra'
require 'pp'
helpers do
def h(txt)
"<h1>#{txt}</h1>"
end
end
before do
puts request.path
end
def r(url, get_handler, post_handler = nil)
get(url){ get_handler.call } if get_handler
post(url){ post_handler.call } if post_handler
end
routes_composite_hash = {
'/' => lambda{ h('index page'); pp params }, #can't access h nor params!!!
'/login' => [lambda{'login page'}, lambda{'login processing'}],
'/postonly' => [nil, lambda{'postonly processing'}],
}
routes_composite_hash.each_pair do |k,v|
r(k, *v)
end
Interesting!
Do this:
def r(url, get_handler, post_handler = nil)
get(url, &get_handler) if get_handler
post(url, &post_handler) if post_handler
end
routes_composite_hash = {
'/' => lambda{ h('index page'); pp params },
'/login' => [lambda{'login page'}, lambda{'login processing'}],
'/postonly' => [nil, lambda{'postonly processing'}],
}
routes_composite_hash.each_pair do |k,v|
r(k, *v)
end
As Kashyap explains, you were calling your get and post handlers inside the main context. This just converts sent lambda to a block and passes it to the desired method.
The methods you define inside helpers do .. end blocks are available only inside routes and filters and views contexts and thus, since you are not using them inside any of those, it won't work. Lambdas preserve the execution context which means that in the hash {'/' => lambda { h }..}, the context is main but inside the get method, the context changes and the helpers are available only in this context.
To achieve what you want to do though, (although I would suggest you avoid doing this), you can just define the helpers as lambdas inside your app file itself. In your case, it would be:
def h(txt)
"<h1>#{txt}</h1>"
end
# And then the rest of the methods and the routes hash
This way, the h method is in the context of the main object and thus will be visible all over.

Padrino controller abstraction

I've been trying Padrino framework in one of my project, and there is one thing that really annoys me. I want to implement just for instance a user registration process using OmniAuth and want to break my request handler (controller's action) to separate methods, like this:
get ":provider/callback" do
#user = find_the_user_by_oauth(request)
create_user unless #user
store_user_in_session
end
def find_the_user_by_oauth(request)
#...
end
def store_user_in_session
session[:user_id] = #user.id
end
I know it would be nicer to push the logic to the model layer, but my question is, how could I break a controller logic to separated methods and share information among them (like using instance variables). In Rails I created these methods in the private scope of my controller, but here I should extend the Application class because it throws Undefined method exception for the previous code. I tried Helpers, but helpers don't know the instance variables, so you should pass the variables every time.
What is the good way to make my controller actions clean in Padrino?
To define a method inside an Padrino Controller you can use define_method instead of def.
For your example, do something like this:
Admin.controllers :dummy do
define_method :find_the_user_by_oauth do |request|
request.params["username"]
# ...
end
define_method :store_user_in_session do
session[:user_id] = #user
end
get :test do
#user = find_the_user_by_oauth(request)
create_user unless #user
store_user_in_session()
session.inspect
end
end
Padrino runs the block sent to Admin.controllers using instance_eval.
See this answer for the differences https://stackoverflow.com/a/3171649 between define_method and def
possible offtopic, but would you consider to use Espresso Framework instead.
then you'll can solve your issue as simple as:
class App < E
def index provider, action = 'callback'
#user = find_the_user_by_oauth
create_user unless #user
store_user_in_session
end
private
def find_the_user_by_oauth
# provider, action are accessed via `action_params`
# action_params[:provider]
# action_params[:action]
end
def store_user_in_session
session[:user_id] = #user.id
end
end

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