问#<UsersController:0x007fda4c2c5208>的未定义方法`user_url

EN

TaskManager::Application.routes.draw do
    get "welcome/index"
    root 'welcome#index'

    get 'users/new' => 'users#new'
    post 'users/' => 'users#create'
    post 'users/:first_name' => 'users#show'
end

class UsersController < ApplicationController    
def new
  @user = User.new
end

def create
  @user = User.new(user_params)
  @user.save

  if @user.save
    redirect_to @user
  else

  end
end

def show
  @user = User.find(params[:first_name])
end

private
  def user_params
    params.require(:user).permit(:first_name, :last_name, :email)
  end
end