Rails 4 - How to Access Params

Question

I am uploading images which POSTs the following params:

Parameters: {"url"=>"https://bucket.s3.amazonaws.com/image014.jpg",
"filepath"=>"/uploads%2F1381509934146-1t5a44loikwhr529-1d68490743e05a1287fea45ed4ed9e59%2Fslide0005_image014.jpg",
"filename"=>"slide0005_image014.jpg", 
"filesize"=>"30807", 
 "filetype"=>"image/jpeg", 
 "unique_id"=>"1t5a44loikwhr529", 
 "choice"=>["https://bucket.s3.amazonaws.com/image014.jpg"]}

And here is my form:

<%= s3_uploader_form callback_url: choices_url, callback_param: "choice[]", id: "s3-uploader" do %>
  <%= file_field_tag :file, multiple: true %>
   <button type="submit" class="btn btn-primary start"> 
<% end %>

And in my controller I have:

#app/controllers/choices_controller

def create
@choice = Choice.create!(choice_params)
  if @choice.persisted?
    respond_to do |format|
      format.html { redirect_to choices_path }
      format.json { head :no_content }
    end
  end
end

def choice_params
  params.require(:choice).permit(:url, :filepath, :filename, :filesize, :filetype)
end

But, it returns the error:

 NoMethodError (undefined method `permit' for #<Array:0x007f903e380060>):
  app/controllers/choices_controller.rb:49:in `choice_params'
  app/controllers/choices_controller.rb:24:in `create'

Can you tell me what I am doing wrong here? All I would like to do is:

1) Add the "url" param to the DB 2) Titlelize the "filename" param and then submit that to the DB.

Thanks very much!

Answer 1

why ?

require works like params[:some_key], except it raises ActionController::ParameterMissing when the value returned is blank.

This is handy because it allows, using rescue_from, to render a 400: bad request error in this case.

what to do ?

So you have to wrap your params so that when you call require(:choice) you get a hash.

Unfortunately s3_upload_form does not seem to support the same builder syntax as form_for, that would allow you to do :

<%= form_for :s3_upload do |f| %>
    <% f.file_field :file %>
<% end %>

resulting in a params hash like this :

 { s3_upload: {file: <SomeFile ...>} }

So my advice would simply be to drop the require call, and to put :choice along the other arguments passed to permit.

If you want to still have the benefits of the require method (that is, checking if a param is missing), you can always do something along the lines of :

def choice_params
  params.permit(:foo, :bar, :baz).tap do |p| 
    p.each_key{ |k| p.require k }
  end
end

this would raise an exception if any of the permitted parameters is missing.