I am rather new to Rails, and would greatly appreciate any bit of help. I have created the following method:
def name_fix
name = self.split
mod_name = []
name.each do |n|
n.split("")
if n[0]
n.upcase
else
n.downcase
end
mod_name.push(n)
end
mod_name.join
end
I would like to use this method in my Controller as such:
def create
#patient = Patient.new(params[:patient])
#patient.name = params[:params][:name].name_fix
if #patient.save
redirect_to patients_path
else
render :new
end
end
How can I go about accomplishing this? Will this method reside within my Model or Controller? Previously, I've run into an undefined method error.
Note: I'm sure that there is a way to better write my code. I am grateful for help with that as well.
#app/models/patient.rb
class Patient < ActiveRecord::Base
protected
def name=(value)
mod_name = []
value.split.each do |n|
n.split("")
type = n[0] ? "up" : "down"
n.send("#{type}case")
mod_name.push(n)
end
#name = mod_name.join
end
end
#app/controllers/patients_controller.rb
class PatientsController < ApplicationController
def create
#patient = Patient.new patient_params
#patient.save ? redirect_to(patients_path) : render(:new)
end
private
def patient_params
params.require(:patient).permit(:name)
end
end
What you're doing is trying to override the setter method, which can be done using the above code. Much more efficient and out of the way.
I have created the following method
Since you're new, let me explain something else.
It is important to note where you're using this method.
You've currently put it in the model, which means you'll have to call it to manipulate some attribute / functionality of any object created with said model.
--
Models - in Rails - build the objects which populate your app. Ruby is an object orientated language, which means that every element of your program should revolve around data objects in some degree.
As you can see above, the method of building objects in your system is really about invoking classes. These classes contain methods which can be called, either at class level (IE invoking the class through the method), or at instance level (IE calling a method on an already invoked object).
This is where you get "class" methods (Model.method) and "instance" methods (#model.method) from:
#app/models/patient.rb
class Patient < ActiveRecord::Base
def explode
#this is an instance method
puts "Instance Explode"
end
def self.explode
#this is a class method
puts "Exploded"
end
end
Thus you can call the following:
#patient = Patient.find params[:id]
#patient.explode #-> "Instance explode"
Patient.explode #-> "Exploded"
--
This is important because it gives you a strict framework of where you should, and shouldn't use methods in your models.
It explains why you have controllers & helpers, and allows you to formulate the best way to structure your application as to get the most out of the least code.
For example...
Your use of #patient.name = params[:params][:name].name_fix is incorrect.
It's wrong because you're calling the instance method .name_fix on a piece of data totally unrelated to your model. If you wanted to use .name_fix in a general sense like this, you'd probably use a helper:
#app/helpers/patients_helper.rb
class PatientsHelper
def name_fix value
# stuff here
end
end
#app/controllers/patients_controller.rb
class PatientsController < ApplicationController
def create
#patient.name = name_fix params[:patient][:name]
end
end
Since you're using the method to populate the .name attribute of your model, it makes sense to override the name= setter. This will not only provide added functionality, but is much smoother and efficient than any other way.
Methods that are called directly are best put in the Controller (or in ApplicationController if you think more than one controller might want to use it).
These are methods like
# app/controllers/my_controller.rb
def foo(bar)
# do something here
end
def create
id = params[:id]
value = foo(id)
end
If you want a chained method that acts as a property method of whatever you're calling it on. Those are characteristic of how Models work - you have your main model and you call attributes or methods on the instance of that model.
# app/models/my_model.rb
def full_name
first_name + " " + last_name
end
# app/controller/my_controller.rb
def create
id = params[:id]
model = MyModel.find(id)
full_name = model.full_name
end
In your case, you want to call name_fix ON whatever is returned by params[:params][:name], which is (I'm guessing) a String.
You have two options
Modify the String class to define a method named name_fix. I highly recommend against this. It's call "monkeypatching" and shouldn't be done without good reason. Just letting you know you can do it in some cases.
Use a direct method in your controller or ApplicationController like the first example above.
#patient.name = name_fix(params[:params][:name])
Edit: As for your request about a better way to write your code... that's difficult to teach or convey in one answer. I'd say read some open source projects out there to see how people write Ruby and some common idioms used to clean up the code. To get you started, here's how I'd re-write your code
def create
#patient = Patient.new(params[:patient])
# 1. Be descriptive with your method names. `name_fix` is vague
# 2. Why is `:name` nested under another `[:params]` hash?
#patient.name = capitalize_name(params[:name])
if #patient.save
# 1. I think `patient_path` has to be singular
# 2. It needs a `Patient` object to know how to construct the URL
# e.g. `/patients/:id`
redirect_to patient_path(#patient)
else
render :new
end
end
def capitalize_name(full_name)
# Example: julio jones
#
# 1. `split` produces an array => ["julio", "jones"]
# 2. `map` applies a function (`capitalize`) to each element
# => ["Julio", "Jones"]
# 3. `join(" ")` rejoins it => "Julio Jones"
full_name.split.map(&:capitalize).join(" ")
end
Assuming your goal with the name_fix method is just to capitalize the first letter of each name, you could just pass name as an argument and store it as a private method on the Controller:
# app/controllers/patient_controller.rb
private
def name_fix(name)
name.split.map(&:capitalize).join(" ")
end
Then you could do
#patient.name = name_fix(params[:params][:name])
in the create method.
OR, you could store this method in the model:
# app/models/patient.rb
def self.name_fix(name)
name.split.map(&:capitalize).join(" ")
end
Then you could do this instead, in the controller:
#patient.name = Patient.name_fix(params[:params][:name])
I would also suggest renaming your name_fix method to something like capitalize_name.
update your create method as below
def create
#patient = Patient.new(params[:patient])
#patient.name = params[:params][:name]
#patient = #patient.name_fix
if #patient.save
redirect_to patients_path
else
render :new
end
end
It should work.
Related
I am trying to assign session values to model object as below.
# models/product.rb
attr_accessor :selected_currency_id, :selected_currency_rate, :selected_currency_icon
def initialize(obj = {})
selected_currency_id = obj[:currency_id]
selected_currency_rate = obj[:currency_rate]
selected_currency_icon = obj[:currency]
end
but this works only when I initialize new Product object
selected_currency = (session[:currency].present? ? session : Currency.first.attributes)
Product.new(selected_currency)
While, i need to set these setter methods on each product object automatically even if was fetched from Database.(active record object) ie. Product.all or Product.first
Earlier i was manually assigning values to each product object after retrieving it from db on controller side.
#products.each do |product|
product.selected_currency_id = session[:currency_id]
product.selected_currency_rate = session[:currency_rate]
product.selected_currency_icon = session[:currency]
end
But then i need to do it on every method where product details need to be displayed. Please suggest a better alternative to set these setter methods automatically on activerecord objects.
I don't think you really want to do this on the model layer at all. One thing you definitely don't want to do is override the initializer on your model and change its signature and not call super.
Your model should only really know about its own currency. Displaying the price in another currency should be the concern of another object such as a decorator or a helper method.
For example a really naive implementation would be:
class ProductDecorator < SimpleDelegator
attr_accessor :selected_currency
def initialize(product, **options)
# Dynamically sets the ivars if a setter exists
options.each do |k,v|
self.send "#{k}=", v if self.respond_to? "#{k}="
end
super(product) # sets up delegation
end
def price_in_selected_currency
"#{ price * selected_currency.rate } #{selected_currency.icon}"
end
end
class Product
def self.decorate(**options)
self.map { |product| product.decorate(options) }
end
def decorate(**options)
ProductDecorator.new(self, options)
end
end
You would then decorate the model instances in your controller:
class ProductsController
before_action :set_selected_currency
def index
#products = Product.all
.decorate(selected_currency: #selected_currency)
end
def show
#product = Product.find(params[:id])
.decorate(selected_currency: #selected_currency)
end
private
def set_selected_currency
#selected_currency = Currency.find(params[:selected_currency_id])
end
end
But you don't need to reinvent the wheel, there are numerous implementations of the decorator pattern like Draper and dealing with currency localization is complex and you really want to look at using a library like the money gem to handle the complexity.
If I have a controller
class MyController < ApplicationController
vals = [...]
def new
...
end
def create
if save
...
else
render 'new'
end
end
how can I make the "vals" variable accessible to both methods? In my "new" view I want to use the "vals" variable for a drop-down menu, but rails is giving me errors. Of course, I could just copy the variable twice, but this solution is inelegant.
As Sebastion mentions a before_ hook / callback is one way to go about it, however as you mentioned it is for a dropdown menu, I am guessing it is a non-changing list, if so I would suggest perhaps using a Constant to define the values, perhaps in the model they are specific to, or if it is to be used in many places a PORO would do nicely to keep things DRY. This will then also allow you to easily access it anywhere, for example in models for a validation check, or to set the options of the dropdown menu in the view, or in the controller if you so wish:
class ExampleModel
DROPDOWN_VALUES = [...].freeze
validates :some_attr, inclusion: { in: DROPDOWN_VALUES }
end
class SomeController < ApplicationController
def new
# can call ExampleModel::DROPDOWN_VALUES here
end
def create
# also here, anywhere actually
end
end
You could use a before_* callback, e.g a before_action, this way you sets your vals variable as an instance one and make it to be available for your both new and create methods, something like:
class SomeController < ApplicationController
before_action :set_vals, only: [:new, :create]
def new
...
# #vals is available here
end
def create
if save
...
# and here
else
render 'new'
end
end
private
def set_vals
#vals = [...]
end
end
A different way from the ones before (although probably just having the instance method is preferred as in Sebastian's solution) is, take advantage of the fact that functions and local variables are called in the same way in ruby and just write:
def vals
#vals ||= [...]
end
and you should be able to access it on the controllers (not the views). If you want it on your views as well you can call at the beginning of the controller
helper_method :vals
If you want to be able to modify vals using vals="some value"
def vals= vals_value
#vals = vals_value
end
Take into account that probably using the intance variable as in Sebastian's solution is preferred, but if you, for whatever reason, are settled on being able to call "vals" instead of "#vals" on the view (for example if you are using send or try), then this should be able to do it for you.
Define in corresponding model
Eg :
class User < ActiveRecord::Base
TYPES = %w{ type1 type2 type3 }
end
and use in ur form like
User::TYPES
=> ["type1", "type2", "type3"]
You can reuse this anywhere in the application.
I use a gem to manage certain attributes of a gmail api integration, and I'm pretty happy with the way it works.
I want to add some local methods to act on the Gmail::Message class that is used in that gem.
i.e. I want to do something like this.
models/GmailMessage.rb
class GmailMessage < Gmail::Message
def initialize(gmail)
#create a Gmail::Message instance as a GmailMessage instance
self = gmail
end
def something_clever
#do something clever utilising the Gmail::Message methods
end
end
I don't want to persist it. But obviously I can't define self in that way.
To clarify, I want to take an instance of Gmail::Message and create a GmailMessage instance which is a straight copy of that other message.
I can then run methods like #gmail.subject and #gmail.html, but also run #gmail.something_clever... and save local attributes if necessary.
Am I completely crazy?
You can use concept of mixin, wherein you include a Module in another class to enhance it with additional functions.
Here is how to do it. To create a complete working example, I have created modules that resemble what you may have in your code base.
# Assumed to be present in 3rd party gem, dummy implementation used for demonstration
module Gmail
class Message
def initialize
#some_var = "there"
end
def subject
"Hi"
end
end
end
# Your code
module GmailMessage
# You can code this method assuming as if it is an instance method
# of Gmail::Message. Once we include this module in that class, it
# will be able to call instance methods and access instance variables.
def something_clever
puts "Subject is #{subject} and #some_var = #{#some_var}"
end
end
# Enhance 3rd party class with your code by including your module
Gmail::Message.include(GmailMessage)
# Below gmail object will actually be obtained by reading the user inbox
# Lets create it explicitly for demonstration purposes.
gmail = Gmail::Message.new
# Method can access methods and instance variables of gmail object
p gmail.something_clever
#=> Subject is Hi and #some_var = there
# You can call the methods of original class as well on same object
p gmail.subject
#=> "Hi"
Following should work:
class GmailMessage < Gmail::Message
def initialize(extra)
super
# some additional stuff
#extra = extra
end
def something_clever
#do something clever utilising the Gmail::Message methods
end
end
GmailMessage.new # => will call first the initializer of Gmail::Message class..
Building upon what the other posters have said, you can use built-in class SimpleDelegator in ruby to wrap an existing message:
require 'delegate'
class MyMessage < SimpleDelegator
def my_clever_method
some_method_on_the_original_message + "woohoo"
end
end
class OriginalMessage
def some_method_on_the_original_message
"hey"
end
def another_original_method
"zoink"
end
end
original = OriginalMessage.new
wrapper = MyMessage.new(original)
puts wrapper.my_clever_method
# => "heywoohoo"
puts wrapper.another_original_method
# => "zoink"
As you can see, the wrapper automatically forwards method calls to the wrapped object.
I'm not sure why you can't just have a simple wrapper class...
class GmailMessage
def initialize(message)
#message = message
end
def something_clever
# do something clever here
end
def method_missing(m, *args, &block)
if #message.class.instance_methods.include?(m)
#message.send(m, *args, &block)
else
super
end
end
end
Then you can do...
#my_message = GmailMessage.new(#original_message)
#my_message will correctly respond to all the methods that were supported with #original_message and you can add your own methods to the class.
EDIT - changed thanks to #jeeper's observations in the comments
It's not the prettiest, but it works...
class GmailMessage < Gmail::Message
def initialize(message)
message.instance_variables.each do |variable|
self.instance_variable_set(
variable,
message.instance_variable_get(variable)
)
end
end
def something_clever
# do something clever here
end
end
Thanks for all your help guys.
I would like to factor a bunch of common code from subclasses into a superclass method. The superclass method must refer to a nonexistent (in the superclass) method that will be defined in the subclasses. But I can't get this to work.
This is one try out of many multiple variations I have tried:
class Superclass
def chunk_of_code
# <code...>
nonexistant_superclass_method_defined_in_subclass params
# <more code...>
end
end
class Subclass < Superclass
def nonexistant_superclass_method_defined_in_subclass params
# whatever...
end
end
Subclass.new.chunk_of_code params
This doesn't work. Other variations don't work either. Is this kind of coding possible in Ruby (I thought it was)? I did this kind of thing all the time working in Smalltalk.
Any way to achieve what I want? Please avoid advising me to use "mix-ins" or "modules," as I'd just like to just learn and use Ruby's inheritance for right now.
*Running latest version of Ruby.
Thanks.
EDIT: This is in a Rails app. The superclass is ApplicationController.
EDIT: Here is actual code from one of many iterations I've tried to do this. This particular example craps out with "undefined method `each' for nil:NilClass" in the view, apparently because the whole thing is running in the context of the super (where it isn't defined) instead of the sub, or at least that's my interpretation:
class ApplicationController < ActionController::Base
protect_from_forgery
before_filter :authenticate_registration!
# models and x defined in subclass
def index
models = x.where registration_id: current_registration.id
respond_to do |format|
format.html # index.html.erb
format.json { render json: models }
end
end
# more code here...
# ...
end
class PositionsController < ApplicationController
def x
Position
end
def models= blah
#positions = blah
end
# more code here...
# ...
end
The only error you have here is the definition of the chunk_of_code. This method has to accept some formal parameter, like:
def chunk_of_code params
And then you're free to call it:
params = 'something'
Subclass.new.chunk_of_code params
Your error is actually nothing to do with inheritance and is on this line
models = x.where registration_id: current_registration.id
This is potentially ambiguous: does this mean call the method models= or does it mean assign to a local variable called models? In this (and similar) situation ruby assumes you're trying to deal with the local variable. If you want to call the method instead you need to do
self.models = x.where registration_id: current_registration.id
Since you models= method doesn't get called, #positions is nil and I assume your view tries to use it.
You might also be interested in gems such as make_resourceful that handle this common controller stuff.
Over on the model side of Rails, I routinely use:
class GenericModel < ActiveRecord::Base
self.abstract_class = true
# define all the generic behavior methods/ model stubs you want.
# model-specific classes can override to their hearts content
# or use the inherited implementation
end
class Feature < GenericModel
# model specific methods, and/or overrides
end
and I use a
class GenericController
# basic show implementation for example
def show
#object = params[:controller].singularize.camelcase.constantize.find(params[:id])
respond_to do |format|
format.pdf { render :layout => false }
format.html # show
format.xml { render :xml => #object.to_xml }
end
end
end
If a specific model's show behavior isn't any different than generic, then that method doesn't appear in that 'model'_controller.rb.
A way to do this is to define it in the parent and raise NotImplementedError as the behavior of the method. By the way what you are trying to do is create an abstract class, which is facilitated more in certain other languages like Java.
I understand my question is a bit vague but I don't know how else to describe it. I've asked in numerous places and no one seems to understand why I want to do this. But please bear with me, and I'll explain why I want something like this.
I'm using Liquid Templates to allow users to make some dynamic pages on my site. And for those that don't know, Liquid uses a class of theirs called LiquidDrop to expose certain items to the user. Any method in the drop can be called by the Liquid template.
class PageDrop < Liquid::Drop
def initialize(page)
#page = page
end
def name
#page.name
end
def children
PagesDrop.new(#page.children)
end
end
class PagesDrop < Liquid::Drop
def initialize(pages)
#pages = pages
end
def group_by
GroupByDrop.new(#pages)
end
def all
#pages.all
end
def size
#pages.size
end
end
For example, I want to be able to do this:
#page_drop = PageDrop.new(#page)
#page_drop.children # to get an array of children
instead of
#page_drop.children.all
Why do I have a pages drop?
Because I want to be able to cleanly split up the methods I can do to an array of pages, and methods I can do to a single page. This allows me to group pages like so:
#page_drop.children.group_by.some_method_here_that_the_group_drop_contains
To make it simpler for my users, I don't want them to have to think about adding "all" or not to a drop instance to get the "default" object/s that it contains. To reiterate:
#pages_drop = PagesDrop.new(Page.all)
#pages_drop == #pages_drop.pages #I want this to be true, as well as
#pages_drop == #pages_drop.all
Where did I get this idea?
In Rails, a scope (association object) (#person.friends) seems to return the array when you do certain things to it: #person.friends.each, for person in #person.friends
This isn't really possible. When you write #instance you aren't really calling an instance as you describe, you're getting a reference to the object that #instance refers to.
The reason it seems to work with the collections for Rails' associations is that the the association objects are instances of Array that have had some of their methods overridden.
I would consider removing PagesDrop and using the group_by(&:method) syntax if you want a concise way to express groupings. If you do want to keep it then you can get some way towards what you want by implementing each and [] on PagesDrop and having them delegate to #pages. That will let you use #page_drop.children in for loops, for instance.
It looks like you want to implement has_many outside of rails. Will the following work?
class PageDrop < Liquid::Drop
attr_accessor :children
def initialize(page)
#page = page
#children = []
end
def name
#page.name
end
end
This allows you to do the following:
#page_drop = PageDrop.new(#page)
#page_drop.children.size # => 0
#page_drop.children # => []
This also gives you all the standard array functions (group_by, size, each, etc). If you want to add your own methods, create a class that inherits from Array and add your methods there.
class PageArray < Array
def my_method
self.each{|a| puts a}
end
end
class PageDrop < Liquid::Drop
attr_accessor :children
def initialize(page)
#page = page
#children = PageArray.new
end
[...]
end
#page_drop = PageDrop.new(#page)
#page_drop.children.size # => 0
#page_drop.children # => []
#page_drop.children.my_method # Prints all the children
Then any functions you don't define in PageArray fall through to the Ruby Array methods.