What route to use to link to resource creator? - ruby-on-rails

Question

My goal is to link the <%= #thing.user.username %> to the user's profile. I know it's something like:
<%= link_to #thing.user.username, %>
But what goes after the comma?
I can currently navigate to a user by going to "localhost:3000/users/UserNameHere". How do I link to that page dynamically?
Each of my Things has a line showing what user posted it. Here is how Things are displayed:
<div class='row'>
<div class='col-md-offset-2 col-md-8'>
<div class='panel panel-default'>
<div class='panel-heading text-center'>
<%= image_tag #thing.image.url(:medium) %>
</div>
<div class='panel-body'>
<p>
<strong><%= #thing.title %></strong>
</p>
<p>
<%= #thing.description %>
</p>
<p>
<%= #thing.user.username %>
</p>
<% if #thing.user == current_user %>
<%= link_to edit_thing_path(#thing) do %>
<span class='glyphicon glyphicon-edit'></span>
<% end %>
<% end %>
</div>
</div>
</div>
Here is my UsersController:
class UsersController < ApplicationController
def show
#user = User.find_by_id(params[:id])
end
end
Here are my routes:
Stynyl::Application.routes.draw do
resources :things
devise_for :users
get '/about', to: 'pages#about'
root 'things#index'
get 'users/:username' => "users#show"
end
Here is my rake routes output:
Prefix Verb URI Pattern Controller#Action
things GET /things(.:format) things#index
POST /things(.:format) things#create
new_thing GET /things/new(.:format) things#new
edit_thing GET /things/:id/edit(.:format) things#edit
thing GET /things/:id(.:format) things#show
PATCH /things/:id(.:format) things#update
PUT /things/:id(.:format) things#update
DELETE /things/:id(.:format) things#destroy
new_user_session GET /users/sign_in(.:format) devise/sessions#new
user_session POST /users/sign_in(.:format) devise/sessions#create
destroy_user_session DELETE /users/sign_out(.:format) devise/sessions#destroy
user_password POST /users/password(.:format) devise/passwords#create
new_user_password GET /users/password/new(.:format) devise/passwords#new
edit_user_password GET /users/password/edit(.:format) devise/passwords#edit
PATCH /users/password(.:format) devise/passwords#update
PUT /users/password(.:format) devise/passwords#update
cancel_user_registration GET /users/cancel(.:format) devise/registrations#cancel
user_registration POST /users(.:format) devise/registrations#create
new_user_registration GET /users/sign_up(.:format) devise/registrations#new
edit_user_registration GET /users/edit(.:format) devise/registrations#edit
PATCH /users(.:format) devise/registrations#update
PUT /users(.:format) devise/registrations#update
DELETE /users(.:format) devise/registrations#destroy
about GET /about(.:format) pages#about
root GET / things#index
GET /users/:username(.:format) users#show

Answer 1

You should stick to REST conventions in Rails, so use resources.
Replace:
get 'users/:username' => "users#show"
with:
resources :users, only: [:show]
then:
<%= link_to #thing.user.username, user_path(#thing.user.username) %>
or:
<%= link_to #thing.user.username, #thing.user %>
#and in model
def to_param
username
end
And replace params[:username] with params[:id] in your action.