My goal is to set an instance variable using AFMotion's AFMotion::HTTP.get method.
I've set up a Post model. I would like to have something like:
class Post
...
def self.all
response = AFMotion::HTTP.get("localhost/posts.json")
objects = JSON.parse(response)
results = objects.map{|x| Post.new(x)}
end
end
But according to the docs, AFMotion requires some sort of block syntax that looks and seems to behave like an async javascript callback. I am unsure how to use that.
I would like to be able to call
#posts = Post.all in the ViewController. Is this just a Rails dream? Thanks!
yeah, the base syntax is async, so you don't have to block the UI while you're waiting for the network to respond. The syntax is simple, place all the code you want to load in your block.
class Post
...
def self.all
AFMotion::HTTP.get("localhost/posts.json") do |response|
if result.success?
p "You got JSON data"
# feel free to parse this data into an instance var
objects = JSON.parse(response)
#results = objects.map{|x| Post.new(x)}
elsif result.failure?
p result.error.localizedDescription
end
end
end
end
Since you mentioned Rails, yeah, this is a lil different logic. You'll need to place the code you want to run (on completion) inside the async block. If it's going to change often, or has nothing to do with your Model, then pass in a &block to yoru method and use that to call back when it's done.
I hope that helps!
Related
I am fairly new to ruby and would like to understand how class instance variables behave in case of multiple parallel requests.
I have a method inside my controller class which is called everytime for each request for a specific operation (create in this case)
class DeployProvision
def self.create(data)
raise "Input JSON not received." unless data
# $logger.info input_data.inspect
failure = false
response_result = ""
response_status = "200"
#validator = SchemaValidate.new
validation = #validator.validate_create_workflow(data.to_json)
end
end
This method is called as (DeployProvision.create(data))
I am a little confused on how #validator class instance variable behaves when multiple requests come. Is it shared among multiple requests. Is it a good idea to declare this as class instance variable instead of a local variable ?
I am working on an existing code base and would like to understand the intent of creating #validator as a class instance variable instead of local variable.
You can write ultra-simple script like this:
require 'sinatra'
class Foo
def self.bar
#test = Time.now
puts #test
end
end
get '/' do
Foo.bar
end
and you'll see it does nothing, because with every call, you're creating new instance of Time(SchemaValidate in your code).
If you used memoization and had something like #validator ||= SchemaValidate.new you would have one instance of SchemaValidate stored between requests.
I don't think that'd change anything in terms of performance and I don't have idea why would anyone do something like that.
You can have some fun with ultra-simple scripts with sinatra to test how it behaves.
Good luck with this code!
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
I'm trying out Rubymotion and can't seem to do figure how to accomplish what seems like a simple task.
I've set up a UITableView for a directory of people. I've created a rails back end that returns json.
Person model has a get_people class method defined:
def self.get_people
BubbleWrap::HTTP.get("http://myapp.com/api.json") do |response|
#people = BW::JSON.parse(response.body.to_str)
# p #people prints [{"id"=>10, "name"=>"Sam"}, {etc}] to the console
end
end
In the directory_controller I just want to set an instance variable for #data to the array that my endpoint returns such that I can populate the table view.
I am trying to do #data = Person.get_people in viewDidLoad, but am getting an error message that indicates the BW response object is being passed instead: undefined methodcount' for #BubbleWrap::HTTP::Query:0x8d04650 ...> (NoMethodError)`
So if I hard code my array into the get_people method after the BW response block everything works fine. But I find that I am also unable to persist an instance variable through the close of the BW respond block.
def self.get_people
BubbleWrap::HTTP.get("http://myapp.com/api.json") do |response|
#people = BW::JSON.parse(response.body.to_str)
end
p #people #prints nil to the console
# hard coding [{"id"=>10, "name"=>"Sam"}, {etc}] here puts my data in the table view correctly
end
What am I missing here? How do I get this data out of bubblewrap's response object and in to a usable form to pass to my controllers?
As explained in the BW documentation "BW::HTTP wraps NSURLRequest, NSURLConnection and friends to provide Ruby developers with a more familiar and easier to use API. The API uses async calls and blocks to stay as simple as possible."
Due to async nature of the call, in your 2nd snippet you are printing #people before you actually update it. THe right way is to pass the new data to the UI after parsing ended (say for instance #table.reloadData() if #people array is supposed to be displayed in a UITableView).
Here's an example:
def get_people
BubbleWrap::HTTP.get("http://myapp.com/api.json") do |response|
#people = BW::JSON.parse(response.body.to_str)
update_result()
end
end
def update_result()
p #people
# do stuff with the updated content in #people
end
Find a more complex use case with a more elaborate explanation at RubyMotion async programming with BubbleWrap
Personally, I'd skip BubbleWrap and go for something like this:
def self.get_people
people = []
json_string = self.get_json_from_http
json_data = json_string.dataUsingEncoding(NSUTF8StringEncoding)
e = Pointer.new(:object)
hash = NSJSONSerialization.JSONObjectWithData(json_data, options:0, error: e)
hash["person"].each do |person| # Assuming each of the people is stored in the JSON as "person"
people << person
end
people # #people is an array of hashes parsed from the JSON
end
def self.get_json_from_http
url_string = ("http://myapp.com/api.json").stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
url = NSURL.URLWithString(url_string)
request = NSURLRequest.requestWithURL(url)
response = nil
error = nil
data = NSURLConnection.sendSynchronousRequest(request, returningResponse: response, error: error)
raise "BOOM!" unless (data.length > 0 && error.nil?)
json = NSString.alloc.initWithData(data, encoding: NSUTF8StringEncoding)
end
I recently found out about ActiveSupport::Notifications. I think it's a great tool to monitor your applications.
I am currently using it outside of Rails to monitor my Sinatra app and it's working great.
However I use it a lot, to instrument custom queries and would like to somehow notify the result of a query:
my_input = "some_query"
ActiveSupport::Notifications.instrument("myapp.create", :input => my_input) do
#stuff
result = search_for my_input
#stuff
result
end
Now I can subscribe to this and can also get the query that was executed (which is available in the payload hash). But I would also like to see the result in my subscriber.
So is there a way to add any custom value to the payload while I am executing the block?
Just stumbled upon your question when I was looking for the same thing.
You can simply pass in a block variable, it will represent your payload to you, and you can fill it up while you're in the block
my_input = "some_query"
ActiveSupport::Notifications.instrument("myapp.create", :input => my_input) do |instrument|
#stuff
result = search_for my_input
instrument[:my_result] = result
#stuff
result
end
In your subscriber create a new event from the passed argument:
ActiveSupport::Notifications.subscribe("myapp.create") do |*args|
event = ActiveSupport::Notifications::Event.new(*args)
Rails.logger.info event.payload
end
I have a Sinatra based REST service app and I would like to call one of the resources from within one of the routes, effectively composing one resource from another. E.g.
get '/someresource' do
otherresource = get '/otherresource'
# do something with otherresource, return a new resource
end
get '/otherresource' do
# etc.
end
A redirect will not work since I need to do some processing on the second resource and create a new one from it. Obviously I could a) use RestClient or some other client framework or b) structure my code so all of the logic for otherresource is in a method and just call that, however, it feels like it would be much cleaner if I could just re-use my resources from within Sinatra using their DSL.
Another option (I know this isn't answering your actual question) is to put your common code (even the template render) within a helper method, for example:
helpers do
def common_code( layout = true )
#title = 'common'
erb :common, :layout => layout
end
end
get '/foo' do
#subtitle = 'foo'
common_code
end
get '/bar' do
#subtitle = 'bar'
common_code
end
get '/baz' do
#subtitle = 'baz'
#common_snippet = common_code( false )
erb :large_page_with_common_snippet_injected
end
Sinatra's documentation covers this - essentially you use the underlying rack interface's call method:
http://www.sinatrarb.com/intro.html#Triggering%20Another%20Route
Triggering Another Route
Sometimes pass is not what you want, instead
you would like to get the result of calling another route. Simply use
call to achieve this:
get '/foo' do
status, headers, body = call env.merge("PATH_INFO" => '/bar')
[status, headers, body.map(&:upcase)]
end
get '/bar' do
"bar"
end
I was able to hack something up by making a quick and dirty rack request and calling the Sinatra (a rack app) application directly. It's not pretty, but it works. Note that it would probably be better to extract the code that generates this resource into a helper method instead of doing something like this. But it is possible, and there might be better, cleaner ways of doing it than this.
#!/usr/bin/env ruby
require 'rubygems'
require 'stringio'
require 'sinatra'
get '/someresource' do
resource = self.call(
'REQUEST_METHOD' => 'GET',
'PATH_INFO' => '/otherresource',
'rack.input' => StringIO.new
)[2].join('')
resource.upcase
end
get '/otherresource' do
"test"
end
If you want to know more about what's going on behind the scenes, I've written a few articles on the basics of Rack you can read. There is What is Rack? and Using Rack.
This may or may not apply in your case, but when I’ve needed to create routes like this, I usually try something along these lines:
%w(main other).each do |uri|
get "/#{uri}" do
#res = "hello"
#res.upcase! if uri == "other"
#res
end
end
Building on AboutRuby's answer, I needed to support fetching static files in lib/public as well as query paramters and cookies (for maintaining authenticated sessions.) I also chose to raise exceptions on non-200 responses (and handle them in the calling functions).
If you trace Sinatra's self.call method in sinatra/base.rb, it takes an env parameter and builds a Rack::Request with it, so you can dig in there to see what parameters are supported.
I don't recall all the conditions of the return statements (I think there were some Ruby 2 changes), so feel free to tune to your requirements.
Here's the function I'm using:
def get_route url
fn = File.join(File.dirname(__FILE__), 'public'+url)
return File.read(fn) if (File.exist?fn)
base_url, query = url.split('?')
begin
result = self.call('REQUEST_METHOD' => 'GET',
'PATH_INFO' => base_url,
'QUERY_STRING' => query,
'rack.input' => StringIO.new,
'HTTP_COOKIE' => #env['HTTP_COOKIE'] # Pass auth credentials
)
rescue Exception=>e
puts "Exception when fetching self route: #{url}"
raise e
end
raise "Error when fetching self route: #{url}" unless result[0]==200 # status
return File.read(result[2].path) if result[2].is_a? Rack::File
return result[2].join('') rescue result[2].to_json
end