Rails - how to send some information from one form to other controller

问题

Firstly, I would like to describe what I am going to do. So, my application is set of tasks (eg. exercises depend on writing computer program) which user it available to send solutions through form and server will have compiled it and return results of process. My problem is that I have model Solution which is presented below:

Solution(id: integer, exercise_id: integer, code: string, user_id: integer,
created_at: datetime, updated_at: datetime, language_id: integer)

and exercise_id, user_id, language_id are foreign keys and postgresql return error that it couldn't be null values... The form which I use to send this information looks like below:

<fieldset style="add">
  <legend>Send solution</legend>
    <%= form_for [@user, @exercise, @solution], url: exercise_solutions_path, :html => { role: "form" } do |f| %>
      <div class="form-group">
        <%= f.label "Source code" %>
        <br>
        <%= f.text_area :code %>
      </div>

      <div class="form-group">
        <%= f.label "Programming language" %>
        <br>
        <%= f.select(:language_id, available_lang) %>
      </div>

      <div class="form-group">
        <%= f.submit "Send", :class => "btn btn-default" %>
      </div>
    <% end %>
</fieldset>

Frankly speaking I don't how to include more information such as user.id or exercise.id. Params look like:

@_params    

{"utf8"=>"✓", "authenticity_token"=>"abwhTn3KrVneli0pCVccoWHyzlI7cRTFK5Wo7DdYRK+lL4GwZ8jUPqdzn8ZznCHsWTkfDAFS2RP6gTkWuk33iw==", "solution"=>{"code"=>"ds", "language_id"=>"C++"}, "commit"=>"Wyślij", "controller"=>"solutions", "action"=>"create", "exercise_id"=>"1"}

SolutionController

class SolutionsController < ApplicationController

  def index
    @solutions = Solution.last(20)
  end

  def new
    @solution = Solution.new
  end

  def create
    @solution = Solution.new(solution_params)
    if @solution.save
      redirect_to @solution
    else
      render :new
    end
  end

  def edit
    @solution = Solution.find(params[:id])
    if @solution.update(solution_params)
      redirect_to @solution
    else
      render :edit
    end
  end

  def destroy
  end

  private

  def solution_params
    params.require(:solution).permit(:language_id, :code)
  end

end

Edit:

<fieldset style="add">
  <legend>Send solution</legend>
    <%= form_for [@user, @exercise, @solution], url: exercise_solutions_path, :html => { role: "form" } do |f| %>
      <div class="form-group">
        <%= f.label "Source code" %>
        <br>
        <%= f.text_area :code %>
      </div>

      <div class="form-group">
        <%= f.label "Programming language" %>
        <br>
        <%= f.select(:language_id, available_lang) %>
      </div>

      <div class="form-group">
        <%= f.hidden_field :exercise_id, value: @exercise.id %>
        <%= f.hidden_field :user_id, value: @user.id %>
        <%= f.submit "Send", :class => "btn btn-default" %>
      </div>
    <% end %>
</fieldset>

回答1:

You could 1) add hidden_fields in your form to set the missing attributes:

<div class="form-group">
  <%= f.hidden_field :exercise_id, value: @exercise.id %>
  <%= f.hidden_field :user_id, value: @user.id %>
  <%= f.submit "Send", :class => "btn btn-default" %>
</div>

Make sure to add these attributes to the solution_params permitted parameters:

def solution_params
  params.require(:solution).permit(:language_id, :code, :exercise_id, :user_id)
end

A better idea would be to manually set the exercise and user in the controller and leave your solution_params as is. That way you're not allowing the exercise and user to be set by mass assignment, which could be spoofed.

So instead do 2) in your controller:

def create
  @solution = Solution.new(solution_params)
  @solution.exercise_id = params[:exercise_id]
  @solution.user_id = params[:user_id]

  if @solution.save
    redirect_to @solution
  else
    render :new
  end
end

I'm assuming that :exercise_id and :user_id are in the URL. If not add them as hidden_fields as needed (but this time not on the form object):

<%= hidden_field_tag :user_id, @user.id %>

Also remember to actually select a language_id from the dropdown before you submit the form.

来源：https://stackoverflow.com/questions/27551355/rails-how-to-send-some-information-from-one-form-to-other-controller