Ruby on Rails编辑/更新方法正在创建一个新对象，而不是更新

Question

I'm having a very similar problem (not quite sure if it's exactly the same) as this post:

Edit method is creating new records, instead of just updating existing ones

^^As you may notice, there is no solution posted.

I have a map set up for our building's network. It's setup as floors=>switches, switches=>jacks. Each are only nested once.

The problem is in my switch edit/update methode. When I click on the edit button for a switch, it redirects me to the correct url (.../switch/1/edit), but I notice right away the form is incorrect. Instead of the button saying "update switch", it says "create switch", and that's exactly what happens. A new switch is created instead of the switch I wanted to update being updated.

Here is relevant code. If you want to see anything else, let me know.

...app/views/switches/_form.html.erb:

<%= form_for([@floor, @switch]) do |f| %>
  <% if @switch.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@switch.errors.count, "error") %> prohibited this switch from being saved:</h2>

      <ul>
      <% @switch.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

...app/controllers/switches_controller.rb:

class SwitchesController < ApplicationController

  def create
    @floor = Floor.find(params[:floor_id])
    @switch = @floor.switches.create(params[:switch])
    redirect_to(@floor)
  end

  def destroy
    @floor = Floor.find(params[:floor_id])
    @switch = @floor.switches.find(params[:id])
    @switch.destroy
    redirect_to(@floor)
  end

  def show
    @floor = Floor.find(params[:floor_id])
    @switch = @floor.switches.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render :json => @switch }
    end
  end

  def edit
    @floor = Floor.find(params[:floor_id])
    @switch = @floor.switches.find(params[:id])
  end

  def update
    @floor = Floor.find(params[:id])
    @switch = @floor.switches.find(params[:id])

    respond_to do |format|
      if @switch.update_attributes(params[:switch])
        format.html { redirect_to @switch, :notice => 'Floor was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render :action => "edit" }
        format.json { render :json => @switch.errors, :status => :unprocessable_entity }
      end
    end
  end

end

Can anyone help figure out why it's going to the create method instead of the update? Thanks!

Answer 1

The error is here, form is always built for new switch

<%= form_for([@floor, @floor.switches.build]) do |f| %>
  <% @switch = @floor.switches.find(params[:id]) %>

Change it to

<%= form_for([@floor, @switch]) do |f| %>

( and remove line )

<% @switch = @floor.switches.find(params[:id]) %>

I don't see new action in the controller, it can looks like

def new
  @floor = Floor.find(params[:floor_id])
  @switch = @floor.switches.build
end