Upload File parameter not coming through to controller

Question

I am fairly new to Rails and have been making steady progress on a Mobile Web App I am working on for our local high school but have run into an issue which I am stumped on. I am hoping the collective knowledge here will point me in the right direction.

I have a model for the school athletes (first name, last name, height, weight, graduation years, - standard stuff) which is working (CRUD via standard scaffold generation) and now I want to add the ability to import records via CSV upload.

In an effort to not reinvent the wheel, I am following this example from Rich on Rails. To get familiar with it, I created a separate Rail project and followed the example and it all works as expected. Great. Now to integrate into my existing project.

Everything seems to integrate fine with one exception - the CSV file is never passed to my model in the params I cannot figure out why. I am sure it is something obvious but I have stared at this problem for several hours and am unable to see what I am doing wrong.

Here is a portion of my Athletes controller:

class AthletesController < ApplicationController
  before_action :set_athlete, only: [:show, :edit, :update, :destroy]

  # GET /athletes
  # GET /athletes.json
  def index
    @athletes = Athlete.all.order(:lastname, :firstname)
  end

  # POST /athletes/import
  # POST /athletes/import.json
  def import
    logger.info(params.to_yaml)
    begin
      Athlete.import(params[:file])
      redirect_to page_path('admin'), notice: "Athletes imported."
    rescue
      redirect_to page_path('admin'), notice: "Invalid CSV file format."
    end
  end

  # GET /athletes/1
  # GET /athletes/1.json
  def show
  end

  # GET /athletes/new
  def new
    @athlete = Athlete.new
  end

  # GET /athletes/1/edit
  def edit
  end

My model looks like this:

class Athlete < ActiveRecord::Base
  # an athlete can be on more than one team
  has_and_belongs_to_many :teams, through: :athletes

  require 'csv'

  ##  CSV import
  def self.import(file)
    CSV.foreach(file.path, headers: true) do |row|

      athlete_hash = row.to_hash # exclude the ? field
      athlete = Athlete.where(id: athlete_hash["id"])

      if athlete.count == 1
        athlete.first.update_attributes
      else
        Athlete.create!(athlete_hash)
      end # end if !athlete.nil?
    end # end CSV.foreach
  end # end self.import(file)

I've added this onto my index view for testing, later on it will be in an admin area:

<div>
<h3>Import a CSV File</h3>
  <%= form_tag import_athletes_path, multipart: true do %>
    <%= file_field_tag :file %>
    <%= submit_tag "Import CSV" %>
  <% end %>
</div>

No matter what I do, I never get the value of the file_field_tag to come through to the controller. If I add other fields using text_field_tag they come through as expected but the file_field_tag value never does.

--- !ruby/hash:ActionController::Parameters
utf8: "✓"
authenticity_token: it3yBxBnzA4UQ/NILP5GNoYJeO5dyg+Z+VfhE/C6p7k=
commit: Import CSV
action: import
controller: athletes

Redirected to http://localhost:3000/
Completed 302 Found in 8ms (ActiveRecord: 0.0ms)

I am stumped - if anyone has any ideas as to what I might be doing wrong, I would be grateful. I have about 300 athletes which I want to import and have no desire to type them in.

Answer 1

It turns out because I am using jQuery Mobile for my framework, I need to add "data-ajax=false" to my form tag. This change to my form allowed the file parameter to be visible in the controller:

<h3>Import a CSV File</h3>
  <%= form_tag(import_athletes_path, { :multipart => true, :'data-ajax' => false }) do %>
    <%= file_field_tag :file %>
    <%= submit_tag "Import CSV" %>
  <% end %>
</div>

A short while ago I recalled reading something about file uploads and jQuery Mobile not working by default. It is due to the standard AJAX navigation employed by jQM.