Querying a join table? - ruby-on-rails

Question

I am trying to do two things:
query an attribute from an inner join table in Rails' Console.
query and displaying the attribute in a view.
These are my Models:
retreat.rb:
class Retreat < ApplicationRecord
belongs_to :user
belongs_to :account
validates :name, presence: true
has_many :retreats_teams
has_many :teams, through: :retreats_teams
accepts_nested_attributes_for :retreats_teams
end
retreats_team.rb:
class RetreatsTeam < ApplicationRecord
belongs_to :team
belongs_to :retreat
end
team.rb:
class Team < ApplicationRecord
belongs_to :account
has_many :team_members
has_many :users, through: :team_members
accepts_nested_attributes_for :team_members
has_many :retreats
has_many :retreats, through: :retreats_teams
end
In Rails' console, if I type:
Retreat.last.teams
I get the output:
irb(main):008:0> Retreat.last.teams
Retreat Load (0.9ms) SELECT "retreats".* FROM "retreats" ORDER BY "retreats"."id" DESC LIMIT $1 [["LIMIT", 1]]
Team Load (0.9ms) SELECT "teams".* FROM "teams" INNER JOIN "retreats_teams" ON "teams"."id" = "retreats_teams"."team_id" WHERE "retreats_teams"."retreat_id" = $1 LIMIT $2 [["retreat_id", 38], ["LIMIT", 11]]
=> #<ActiveRecord::Associations::CollectionProxy [#<Team id: 56, name: "My house", account_id: 2, created_at: "2020-02-10 15:57:25", updated_at: "2020-02-10 15:57:25">]>
irb(main):009:0>
How do I retrieve the team name: "My house"?
Also, there might be many teams that display here, too.

Answer 1

#teams returns a collection of team objects. The simplest solution is to call first on the teams to get the first team in the collection:
Retreat.last.teams.first.name
=> "My house"
But if you want all the names in teams you might use pluck. This will allow you to do this:
retreat = Retreat.last
foo = Team.create(name: 'Foo')
bar = Team.create(name: 'Bar')
retreat.teams << foo
retreat.teams << bar
retreat.teams.pluck(:name).to_sentence
=> "My house, Foo, and Bar"

Answer 2

A word on naming
The naming convention for join models is SingularSingular. The table should be named singular_plural. has_and_belongs_to_many is the only part of Rails that actually uses the oddball plural_plural naming scheme.
RetreatsTeam # bad
RetreatTeam # better
Even better though is to actually give your join tables meaningful names instead of just placeholder names.
1) querying an attribute from an inner join table in Rails Console.
Since the association between Retreat and RetreatsTeams in one to many you can actually only fetch aggregates. Otherwise which attribute should it fetch, from the first row, the last row or all the rows?
So for example you can do:
Retreat.joins(:retreats_teams)
.select('retreats.*', 'COUNT(retreats_teams.*) AS retreats_teams_count')
If you are storing more data on the join table that you want to display you want to iterate through the join table:
#retreat = Retreat.eager_load(retreats_teams: :teams).first
#retreat.retreats_teams.each do |rt|
puts rt.foo
puts rt.team.name
end
2) querying and displaying the attribute in a view.
In Rails you're usually just fetching records in the controller and then iterating through them in the view:
class ResortsController < ApplicationController
def show
#resort = Resort.includes(:teams).find(params[:id])
end
end
# app/views/resorts/show.html.erb
<h1><%= #resort.name %></h1>
<h2>Teams</h2>
<% if #resort.teams.any? %>
<ul>
<% #resort.teams.each do |team| %>
<li><%= team.name %></li>
<% end %>
</ul>
<% else %>
<p>This resort has no teams</p>
<% end %>