rails 4重定向到最近创建的记录？

Question

Building a simple messaging app, using this tutorial , and wanted to know if it's possible for me to redirect to the most recent updated record in the database?

application.html.haml :

= link_to 'Messages', :conversations

I want to be able to change this to localhost:3000/messages and then it'll automatically gets redirected to the most recent message recorded.

routes.rb

resources :conversations do
  resources :messages
end

conversation.rb

class Conversation < ActiveRecord::Base
  belongs_to :sender, :foreign_key => :sender_id, class_name: 'User'
  belongs_to :recipient, :foreign_key => :recipient_id, class_name: 'User'

  has_many :messages, dependent: :destroy

  validates_uniqueness_of :sender_id, :scope => :recipient_id

  scope :between, -> (sender_id,recipient_id) do
    where("(conversations.sender_id = ? AND conversations.recipient_id =?) OR (conversations.sender_id = ? AND conversations.recipient_id =?)", sender_id,recipient_id, recipient_id, sender_id)
  end

end

messange.rb

class Message < ActiveRecord::Base
  belongs_to :conversation
  belongs_to :user
  validates_presence_of :body, :conversation_id, :user_id

  def message_time
    created_at.strftime("%m/%d/%y at %l:%M %p")
  end
end

messages_controller.rb

def index
  @conversations = Conversation.all
  @messages = @conversation.messages
  if @messages.length > 10
    @over_ten = true
    @messages = @messages[-10..-1]
  end
  if params[:m]
    @over_ten = false
    @messages = @conversation.messages
  end
  if @messages.last
    if @messages.last.user_id != current_user.id
      @messages.last.read = true;
    end
  end

  @message = @conversation.messages.new
end

Not sure what information is needed, but just wanted to see if this was possible.

Answer 1

I would do the following:

routes.rb

get 'messages', to: 'messages#most_recent'

message.rb

class Message < ActiveRecord::Base
  belongs_to :conversation
  belongs_to :user
  #Create a scope for get the most recent record
  scope :most_recent, :order => "created_at DESC", :limit => 1
  validates_presence_of :body, :conversation_id, :user_id

  def message_time
    created_at.strftime("%m/%d/%y at %l:%M %p")
  end
end

messages_controller.rb

def most_recent
  @message = Message.most_recent.first
end

Then you can use @message for display the most recent message in a messages/most_recent.html.erb view.

But if you still want to keep your index controller action working, then you will need to add a condition.

You will need to add a separate route for most_recent controller action

routes.rb

get 'messages/most_recent' #In this case is not necessary to specify controller action with to:

Then in your index controller action

messages_controller.rb

def index
  if SOME CONDITION HERE
    redirect_to messages_most_recent_path
  else
    @conversations = Conversation.all
    @messages = @conversation.messages
    if @messages.length > 10
      @over_ten = true
      @messages = @messages[-10..-1]
    end
    if params[:m]
      @over_ten = false
      @messages = @conversation.messages
    end
    if @messages.last
      if @messages.last.user_id != current_user.id
        @messages.last.read = true;
      end
    end

    @message = @conversation.messages.new
  end
end

def most_recent
  @message = Message.most_recent.first
end