Ruby On Rails Error 204 generate an image into a new view from controller

Question

I have in my controller a method to create a custom qr

def generate_qrcode()
require 'rqrcode'
qrcode = RQRCode::QRCode.new('ejemplo')
image = qrcode.as_png(
        resize_gte_to: false,
        resize_exactly_to: false,
        fill: 'white',
        color: 'black',
        size: 120,
        border_modules: 4,
        module_px_size: 6,
        file: nil # path to write
        )
 return image.resize(150, 150)
end

and in my main view, i edit a li, to redirect to my generate_qrcode()

index.html.erb

<p id="notice"><%= notice %></p>

<h1>Beneficios</h1>

<table>
  <thead>
    <tr>
      <th>Id sucursal</th>
      <th>Nombre</th>
      <th>Estado</th>
      <th>Descripcion</th>
      <th>Tipo</th>
      <th colspan="3"></th>
    </tr>
  </thead>

  <tbody>
    <% @beneficios.each do |beneficio| %>
      <tr>
        <td><%= beneficio.Id_sucursal %></td>
        <td><%= beneficio.Nombre %></td>
        <td><%= beneficio.Estado %></td>
        <td><%= beneficio.Descripcion %></td>
        <td><%= beneficio.Tipo %></td>
        <td><%= link_to 'Show', beneficio %></td>
        <td><%= link_to 'Edit', edit_beneficio_path(beneficio) %></td>
        <td><%= link_to 'Destroy', beneficio, method: :delete, data: { confirm: 'Are you sure?' } %></td>
        <td><%= link_to 'Qr', :controller => :beneficios, :action => :generate_qrcode %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

<%= link_to 'New Beneficio', new_beneficio_path %>

and in my routes

resources :beneficios do
    collection do
      get :generate_qrcode
    end
  end

however when i try to generate the qr, i keep receiving this error message

i search for answers but i cannot find something that can help me to figure out this.

Answer 1

That's because the controller is expecing you to return a html template with the same name as the action.

What you can do is create a new view with the same name as the action ( views/generate_qrcode.html.erb ).

Save the qr code image in an instance variable:

def generate_qrcode()
require 'rqrcode'
qrcode = RQRCode::QRCode.new('ejemplo')
image = qrcode.as_png(
        resize_gte_to: false,
        resize_exactly_to: false,
        fill: 'white',
        color: 'black',
        size: 120,
        border_modules: 4,
        module_px_size: 6,
        file: nil # path to write
        )
 @qr_code_img = image.resize(150, 150)
end

Then populate the view you created in order to show the qr code image:

<%= image_tag @qr_code_img %>

Answer 2

To render raw binary data (such as an image) from a controller, use send_data :

send_data(image.to_s, type: 'image/png', disposition: 'inline')

I recommend generating your QR code in a private method, then rendering that from your controller action:

class BeneficiosController < ApplicationController
  require 'rqrcode'

  def generate_qrcode
    qrcode = make_qrcode
    send_data qrcode.to_s, type: 'image/png', disposition: 'inline'
  end

  private

  def make_qrcode
    qrcode = RQRCode::QRCode.new('ejemplo')
    image = qrcode.as_png(
        resize_gte_to: false,
        resize_exactly_to: false,
        fill: 'white',
        color: 'black',
        size: 120,
        border_modules: 4,
        module_px_size: 6,
        file: nil # path to write
        )
    image.resize(150, 150)
  end
end

Answer 3

You can't return an image object in controller to render it. You need to call a view template. In your case, you can make your qrcode or image an instance variable and pass it to a template named 'template_qrcode'.

Since you want to show qr code, it might be more user friendly to show it in a popup like a modal window rather than redirect user to a different page. You can generating all your qr code modals in your index action, or use Ajax to generate it on demand.