Week 11 lesson

lesson.markdown

Lecture Notes

Helpers

View helpers are useful files that contain reusable code in an attempt to keep your views DRY and clean. They can be found in the /app/helpers directory. You can simply add methods here that you intend to reuse in your views.

Let's say you want to method to format a date object a specific way all the time (January 1, 2019). You could create a method here called mint_date(date) and place your logic inside. This method then can be used anywhere in any view.

In /app/helpers/application_helper.rb:

module ApplicationHelper
  def mint_date(date)
    date.strftime('%B %e, %Y')
  end
end

In /app/views/months/show.html.erb:

Summary for <%= mint_date(@report.start_date) %>

Model Scopes

So you might've noticed that we always probably want our transactions to be order by date and not by ID. There is a simple way to ensure that our records always get returned by date by adding a model scope to our transaction model. https://guides.rubyonrails.org/active_record_querying.html#scopes

in /app/models/transaction.rb add:

scope :by_date, -> { order(date: :desc) }

this is literally the same as writing

def self.by_date
  order(date: :desc)
end

Just a bit more concise

Now in /app/controllers/transactions_controller.rb you can replace @transactions = Transaction.order(date: :desc).all with @transactions = Transaction.by_date.all.

before_action

We've used when implementing out clearance authentication in our /app/controllers/backend_controller.rb

before_action :require_login

helper_method

Take a look at /app/controllers/transactions_controller.rb and notice how many times we are doing Transaction.find(params[:id]) we can make this much more DRY by using helper_method https://api.rubyonrails.org/classes/AbstractController/Helpers/ClassMethods.html#method-i-helper_method

In the private area of our controller let's add:

def transaction
  @transaction ||= Transaction.find(params[:id])
end

This method says to set the variable @transaction to be Transaction.find(params[:id]) ONLY if it's not already set whenever transaction is called. This means it gives us the ability to explicitly set @transaction if we need to.

Next add as the first line in your controller class:

helper_method :transaction

Now the method transaction will now be available in your view

You can update your actions to remove @transactions wherever necessary like in show, edit, update, destroy. And explicitly set it for new and create.

class TransactionsController < BackendController
  helper_method :transaction

  def index
    @transactions = Transaction.order(date: :desc).all
  end

  def show; end

  def new
    @transaction = Transaction.new
  end

  def create
    @transaction = Transaction.new(transaction_params)
    if @transaction.save
      redirect_to transaction_path(@transaction)
    else
      render :new
    end
  end

  def edit; end

  def update
    if transaction.update(transaction_params)
      redirect_to transaction_path(@transaction)
    else
      render :edit
    end
  end

  def destroy
    transaction.destroy
    redirect_to transactions_path
  end

  private

  def transaction
    @transaction ||= Transaction.find(params[:id])
  end

  def transaction_params
    params.require(:transaction).permit(:name, :amount, :date, :transaction_type, :notes, :category_id)
  end
end

Next we should replace @transaction (calls the variable) with transaction (calls your new method, which returns the variable) in the transaction views