Rails how to render partial with data form database-CodePudding

i have a view called week.haml and a controller action called def week in which I get all my todos for this week. I want to render a partial called _events.haml inside week.haml which displays all events that week.

I did it like this:

inside week.haml:

= render partial: 'events`

inside _events.haml

%p= 'Events this week:'

@events.each do |event|
# stuff to show events
end

inside the todo controller:

def events
  @events = Event.where(some query)
end

But i always get the error message @events not defined. How can i load events into the event partial? and i don't want to do it inside def week if possible...

I also created a route:

resources :todo do
  get 'events', action: :events, as: :events
end

The week.haml file works fine, just the partial doesn't work.

CodePudding user response：

It is bad practice to use instance variables in partials, pass locals instead. Instance variables are for views

In your week view

= render partial: 'events`, events: week.events

And in partial _events

events.each do |event|
  # stuff to show events
end

CodePudding user response：

If you're in the controller action week, you'll need to get the events there or share @events between the different controller actions. If you're in the same scope (same controller in this case), you could create a private method for getting data that's similar between different views.

class TodoController < ApplicationController
  before_action :get_events, only: [:week, :events]

  def week
    # Stuff for the week view
  end

  def events
    # Stuff for the events view
  end

  private
  
  def get_events
    @events = Event.where(...)
  end
end

In this example, the @events variable is available for both actions week and events. The before_action at the top runs get_events to load the @events variable before executing any other code in the controller action. Since it's an instance variable, it can be shared between different methods in the same class. Calling get_events at the top of both week and events would achieve the same result, but a before_action is usually cleaner IMO.

And just to be clear, all of this is assuming that you have separate views events.haml and week.haml. If not, creating a route and a controller method with the name of the partial does nothing. Just load the events in the week controller action and you're good to go! You could essentially think of a controller method as corresponding to a single view (of the same name usually), and a partial is just an extension of that view (and any other views that use the same partial). You load any data you might need for the view or any of its partials in the controller action, and then share whatever's needed with the partial. Instance variables (starting with "@") are shared automatically, but anything else you would need to pass to the partial explicitly.

Partials are meant for things you need to render multiple times (and/or in multiple places). The Rails docs have a pretty thorough section about them. If you're only rendering events for a single week in week.haml, you probably don't even need the partial, unless you want to use it in other views.