Ruby on Rails控制器语法

Question

I am new to Rails, and just working my way through my first solo project, but I seem to be running into a syntax error with a constant not being initialized (Ive gotten several of these, but each seems to have a different cause.....not quite sure how i keep getting the same error with different causes :)):

uninitialized constant DatastringsController::Datastrings

DatastringsController:

class DatastringsController < ApplicationController

  def new

  end

  def create
    @datastrings = Datastrings.new(datastrings_params) #ERROR returned on this line
    @datastrings.save
    redirect_to @datastrings
  end

  def show
    @datastrings = Datastrings.find(params[:id])
  end

  private

  def datastrings_params
    params.require(:datastrings).permit(:title, :text)
  end

end

I believe my form is correct:

<%= form_for :datastrings, url: datastrings_path do |f| %>
  <p>
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </p>

  <p>
    <%= f.label :text %><br>
    <%= f.text_area :text %>
  </p>

  <p>
    <%= f.submit %>
  </p>
<% end %>

Answer 1

The main problem you have is here:

<%= form_for :datastrings, url: datastrings_path do |f| %>

form_for really should be populated with an ActiveRecord object, as this allows Rails to build the relative paths it requires correctly.

Although I don't know why this is the case, your current setup is basically trying to render DatastringsController::Datastrings -- primarily because you've not set up your form_for correctly

--

Fix

If you want to create a datastring object, I'd follow convention and do this:

#config/routes.rb
resources :datastrings

#app/controllers/datastrings_controller.rb
Class DatastringsController < ApplicationController
   def new
      @datastring = Datastring.new
   end

   def create
      @datastring = Datastring.new(datastring_params)
      @datastring.save
   end

   private

   def datastring_params
      params.require(:datastring).permit(:title, :text)
   end
end

#app/views/datastrings/new.html.erb
<%= form_for @datastring do |f| %>
   <%= f.text_field :name %>
   <%= f.submit %>
<% end %>

--

YOU ALSO NEED TO NAME YOUR MODELS IN SINGULAR

Looking at it now, it seems that your main issue is likely that you've named your model as a plural .

The reason this will be bad is that when you load Rails, it will load all your models, and consequently, allow you to call them by referencing their class name. If a model is plural, I don't think it will load it correctly, causing the error you've highlighted

If you name your model to the following, it should be better:

#app/models/datastring.rb
Class Datastring < ActiveRecord::Base
end