I'm getting an error when trying to call a method in my controller. Following tutorials on how to get this to work but just a bit stuck in the mud and need some help.
NoMethodError in CatalogController#index
undefined method `art' for #<Class:0x007fbe8c338310>
My model
require 'httparty'
require 'json'
class Feed < ActiveRecord::Base
include HTTParty
base_uri 'https://www.parsehub.com/api/v2/runs'
# GET /feeds
# GET /feeds.json
def art
response = self.class.get("/tnZ4F47Do9a7QeDnI6_8EKea/data?&format=json")
#elements = response.parsed_response["image"]
#parsed = #elements.collect { |e| e['url'] }
end
end
My controller
class CatalogController < ApplicationController
def index
#images = Feed.art
end
end
I'm guessing it's something fairly simple I'm forgetting.
def art defines an instance method, not a class method.
You have two options to fix this problem:
1) Make the method a class method by adding self. to the definition:
def self.art
# ...
2) Or create a Feed instance in your controller before calling art:
def index
#images = Feed.new.art
end
Related
How can I create an app in Rails that will let me input search parameters, which are then passed to an external API to perform the search, and then display those results in my app. I'm trying to use HTTParty to achieve this but I'm a bit lost. I've tried creating a class method in app/services and accessing it in my controller, and then calling the instance variable in my view. At the moment it's throwing a Routing Error uninitialized constant ResultsController::Api. Would be super grateful for some help.
services/Api.rb
class Api
include HTTParty
base_uri "search.example.com"
attr_accessor :name
def initialize(name)
self.name = name
end
def self.find(name)
response = get("/results&q=#{name}")
self.new(response["name"])
end
results_controller.rb
class ResultsController < ApplicationController
include Api
def index
#results = Api.find('test')
end
end
Routes:
Rails.application.routes.draw do
resources :results
root 'results#index'
end
You're almost right, just need some changes here. At first, rename Api.rb to api.rb - by convention, all files should be named in lower snake_case
class Api
include HTTParty
base_uri "http://search.spoonflower.com/searchv2"
def find(name)
self.class.get("/designs", query: { q: name }).parsed_response
end
end
class ResultsController < ApplicationController
def index
# here you get some json structure that you can display in the view
#results = Api.new.find('test')['results']
end
end
I have the following class
class EvaluateService
def initialize
end
def get_url
end
def self.evaluate_service
#instance ||= new
end
end
class CheckController < ApplicationController
def index
get_url = EvaluateService.get_url
end
end
The problem here is that i know that i can do evaluate_service = EvaluateService.new and use the object evaluate_service.get_url and it will work fine but i also know that some frown upon the idea of initializing the service object this way and rather there is a way of initializing it via a call, send method in the service class.
Just wondering how do i do this?
I think what you're looking for is something like:
class Evaluate
def initialize(foo)
#foo = foo
end
def self.call(foo)
new(foo).call
end
def call
url
end
private
def url
# Implement me
end
end
Now you can do this in your controller:
class CheckController < ApplicationController
def index
#url = Evaluate.call(params)
end
end
The reason some prefer #call as the entry point is that it's polymorphic with lambdas. That is, anywhere you could use a lambda, you can substitute it for an instance of Evaluate, and vice versa.
There are various ways to approach this.
If the methods in EvaluateService don't need state, you could just use class methods, e.g.:
class EvaluateService
def self.get_url
# ...
end
end
class CheckController < ApplicationController
def index
#url = EvaluateService.get_url
end
end
In this scenario, EvaluateService should probably be a module.
If you want a single global EvaluateService instance, there's Singleton:
class EvaluateService
include Singleton
def get_url
# ...
end
end
class CheckController < ApplicationController
def index
#url = EvaluateService.instance.get_url
end
end
But global objects can be tricky.
Or you could use a helper method in your controller that creates a service instance (as needed) and memoizes it:
class EvaluateService
def get_url
# ...
end
end
class CheckController < ApplicationController
def index
#url = evaluate_service.get_url
end
private
def evaluate_service
#evaluate_service ||= EvaluateService.new
end
end
Maybe even move it up to your ApplicationController.
I am trying to access helper method in my controller using helpers like below:
class MyController < ApplicationController
def index
#foo = 'bar'
helpers.my_helper_method
end
end
Inside Helper method, I am trying to access an instance variable of controller
module MyHelper
def my_helper_method
#some manipulation on foo
#foo.to_i
end
end
But in above scenario #foo is nil. When I call the same method from view, #foo is available. So the instance variable can be passed to helper method only through UI or some other way is there?
Thanks in advance.
UPDATE:
view_context
seems like reasonable solution https://apidock.com/rails/AbstractController/Rendering/view_context
class MyController < ApplicationController
def index
#foo = 'bar'
helpers.my_helper_method(#foo)
end
end
module MyHelper
def my_helper_method(foo)
#some manipulation on foo
foo.to_i
end
end
pass it as argument.
You can access instance variables that you set in a controller in your helpers. If the value is nil, then you need to deal with it in your helper:
module SomeHelper
def do_something
return 0 if !#value
value * 3
end
end
class SomeController
def index
#value = 1
helpers.do_something
end
def show
#value = nil
helpers.do_something
end
end
I have the following helper
module AvatarHelper
# Todo: set a defatul profile-image-path
DEFAULT_PROFILE_IMAGE_PATH = "http://image_here"
def avatar_path(user, size = 24)
..
end
def get_facebook_profile_pic user, size
..
end
def get_gravatar_path user, size
..
end
end
When I try to call the helper method in controller, it results in the following error:
undefined method `avatar_path' for AvatarHelper:Module
Here is my controller for reference:
class DashboardController < ApplicationController
before_action :authenticate_user!
def index
#dashboard = Dashboard.new(current_user)
puts AvatarHelper.avatar_path(current_user)
end
end
When I reference other helpers, I see they don't need to reference the helper elsewhere.
module TitleHelper
SITE_TITLE = 'My Site'
TITLE_SEPARATOR = ' ยท '
DESCRIPTION_CHARACTER_LIMIT = 140
def title(*parts)
parts << SITE_TITLE
provide(:title, parts.compact.join(TITLE_SEPARATOR))
end
end
I can then just add the title method directly in the view.
<% title 'myPage' %>
Module methods cannot be invoked directly. They should be included in the class to invoke. That's why they are called mixins(they can be mixed with others).
Here you can include the module in your controller.
class DashboardController < ApplicationController
include AvatarHelper
def index
#dashboard = Dashboard.new(current_user)
puts avatar_path(current_user)
end
end
def self.avatar_path(user, size = 24)
..
end
you are calling instance method add self before mthod will work for you.
Add the following code in your helper.
module AvatarHelper
extend ActiveSupport::Concern
Now you can directly call your method by name like
puts avatar_path(current_user)
Here's the code:
class SyncController < ApplicationController
def get_sync
#passed_ids = params[:ids].split(',')
#users = #passed_ids.collect{|id| User.find(id)}
#add the current user to the list
#users << current_user
#recommendations = get_recommendations(#users)
end
end
module SyncHelper
def get_recommendations(users)
users
end
end
I'm getting a can't find get_recommendations method error...
Your SyncHelper module needs to be included into your SyncController class. You can either add the line
include SyncHelper
in your class definition, or, if SyncHelper lives in the expected app/helpers file, you can use the rails helper method.