Querying and linking to from join tables - ruby-on-rails

Question

Two Questions:
1) I have a retreats/:id view where I can display the team names that are affixed to a specific retreat. I can view the team names with the following query in the view:
<p>Teams: <%= #retreat.teams.pluck(:name).to_sentence %></p>
However, instead of just displaying the name, how would I both display the name of the team and link to the team team/:id
2) In this retreats/:id view, I would also like to display the users that are part of a team, but I am really stuck trying to go through sql joins, etc.
models
retreat.rb
class Retreat < ApplicationRecord
belongs_to :user
delegate :name, to: :user, prefix: true
belongs_to :account
validates :name, presence: true
has_many :retreat_teams
has_many :teams, through: :retreat_teams
accepts_nested_attributes_for :retreat_teams
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: :retreat_teams
end
team_members.rb
class TeamMember < ApplicationRecord
belongs_to :team
belongs_to :user
end

Answer 1

First part can be done this way
<% retreat.teams.each do |team| %>
<%= link_to(team.name, team_path(team.id)) %> # or whatever the path helper is
<% end %>
Second part, you can run this query instead
#teams = Team.where(retreat_id: #retreat.id).includes(:users)
Then in UI you can show like this
<% #teams.each do |team| %>
Team: <%= link_to(team.name, team_path(team.id)) %> # or whatever the path helper is
Team Users: <%= team.users.pluck(:name).to_sentence %>
<% end %>
Hope that helps!

Answer 2

1) I have a retreats/:id view where I can display the team names that
are affixed to a specific retreat. ...However, instead of just
displaying the name, how would I both display the name of the team and
link to the team team/:id
Don't use .pluck unless you actually want just a single column as an array or the raw data from several columns without instantiating model instances. .pluck is both overused and misused. It makes zero sense to pluck something if you then need to fetch the rest of the columns later anyways.
Instead just iterate though the model instances:
<% #resort.teams.each do |team| %>
<%= link_to team.name, team %>
<% end %>
If you have declared the route with resources :teams. Rails will figure out the route all by itself - that's the power of convention over configuration.
2) In this retreats/:id view, I would also like to display the users
that are part of a team, but I am really stuck trying to go through
sql joins, etc.
You don't really have to do any work joining. Just eager_load the association to avoid n+1 queries:
def show
#resort = Resort.eager_load(teams: :users).find(params[:id])
end
<% #resort.teams.each do |team| %>
<div class="team">
<h3><%= link_to team.name, team %></h3>
<h4>Members:</h4>
<% if team.users.any? %>
<ul>
<%= team.users.each do |user| %>
<li><%= link_to user.name, user %></li>
<% end %>
<ul>
<% end %>
</div>
<% end %>
Another note about naming
The name TeamMember is unfortunate as it implies that its the actual person that's a member and not just a join model.
Membership or Position are better name choices.
class Team
has_many :memberships
has_many :members, through: :memberships
end
class Membership
belongs_to :team
belongs_to :member, class_name: 'User'
end
class User
has_many :memberships, foreign_key: :member_id
has_many :teams, through: :memberships
end
This will let you iterate through team.members and actually get the users instead of some join model. The above example would read after refactoring:
def show
#resort = Resort.eager_load(teams: :members).find(params[:id])
end
<% #resort.teams.each do |team| %>
<div class="team">
<h3><%= link_to team.name, team %></h3>
<h4>Members:</h4>
<% if team.members.any? %>
<ul>
<%= team.members.each do |member| %>
<li><%= link_to member.name, member %></li>
<% end %>
<ul>
<% end %>
</div>
<% end %>