Best practice - Passing instance variables or using params in Ruby on Rails views?

Question

According to the following example, What's the best practice?

Case 1

controller.rb ...

def index
  ...
  @group = params[:group]
  @team = params[:team]
  @org = params[:org]
  ...
end

index.html.haml

= link_to @group, '#'
= link_to @team, '#'
= link_to @org, '#'

Case 2

controller.rb ...

def index
  ...

  ...
end

index.html.haml

= link_to params[:group], '#'
= link_to params[:team], '#'
= link_to params[:org], '#'

Or maybe there is another option, like passing only one instance variable of Hash type...

Thanks!

Answer 1

Generally it's a better idea to split out your parameters as instance variables, especially if you need to do some cleaning up on them. Using params directly inside a view is a bit messy, and has the effect of needlessly tying the view to the structure of the incoming parameters.

It's the controller's job to intermediate between the incoming parameters and the view itself. It should convert from one format to another so that you can make a change to the parameters without affecting the view, and to the view without changing the requirements for the parameters.

It's unusual to pass through parameters without doing some kind of processing on them. Most of the time, incoming parameters are used to fetch records from a database, or are used in routing in some capacity.

Seeing three parameters being passed in and then used literally on the page is not a common use case. Why are you passing these in instead of passing a reference to one of these things that can be used to determine the others?

For example:

@team = Team.find_by_slug(params[:team_id])
@org = @team.org
@group = @team.group

This is how most Rails applications are constructed.