Ruby: Object not instantiated by new method with an initialize method - ruby-on-rails

Question

Use case: Upload and process a csv file and record the upload session in the database.
Approach: Create a model to hold data about the upload session and a controller with a new method that collects the csv file and a create method that creates, populates and saves an upload object.
Problem: The model includes an initialize method (see Model code) that seems to have the necessary information to initialize the object (see debug output), but, when the controller attempts to use the model's new method, the attempt does not result in a useful object (see controller code and debug output).
Question: What do I need to change to create the call_history_upload object?
Ruby 1.9.3 on Rails 3.2.13 on Windows 8.1
Model Code:
class CallHistoryUpload < ActiveRecord::Base
attr_accessible :file_name, :user_id, :record_count, :international_call_count, :unknown_client_count
has_many :call_histories, dependent: :destroy
require 'csv'
def initialize( file_name, user_id )
logger.debug( "CallHistoryUpload.initialize start")
logger.debug( " call_history_file = " + file_name )
logger.debug( " user_id = " + user_id )
#file_name = file_name
#user_id = user_id
#record_count = 0
#international_call_count = 0
#unknown_client_count = 0
logger.debug( "CallHistoryUpload.initialize end")
end
end
Controller code:
class CallHistoryUploadsController < ApplicationController
def get_client_id
-1
end
# GET /call_history_uploads/new
# GET /call_history_uploads/new.json
def new
#call_history_upload = CallHistoryUpload.new( "Unknown", session[:user_id] ) # Needed to suppoprt json
respond_to do |format|
format.html # new.html.erb
format.json { render json: #call_history_upload }
end
end
# POST /call_history_uploads
# POST /call_history_uploads.json
def create
logger.debug( "CallHistoryUploadsController start")
#call_history_upload = CallHistoryUpload.new( params[:call_history_file].original_filename, session[:user_id] )
logger.debug( "CallHistoryUploadsController after instantiation")
<<This is line 24>>logger.debug( "call_history_upload.file_name = " + #call_history_upload.file_name )
respond_to do |format|
if #call_history_upload.save
format.html { redirect_to #call_history_upload, notice: 'Call history upload was successful.' }
format.json { render json: #call_history_upload, status: :created, location: #call_history_upload }
else
format.html { render action: "new" }
format.json { render json: #call_history_upload.errors, status: :unprocessable_entity }
end
end
end
end
log output:
Started POST "/call_history_uploads" for 127.0.0.1 at 2014-11-30 08:40:27 -0500
Processing by CallHistoryUploadsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"iDugtKa8b/U9q71Gk86sJMK6hnX1gvgQt496PX2q4Oo=", "call_history_file"=>#<ActionDispatch::Http::UploadedFile:0x4717788 #original_filename="Test_kiyvivzokpysxilfoftavyuftot.csv", #content_type="application/vnd.ms-excel", #headers="Content-Disposition: form-data; name=\"call_history_file\"; filename=\"Test_kiyvivzokpysxilfoftavyuftot.csv\"\r\nContent-Type: application/vnd.ms-excel\r\n", #tempfile=#<File:C:/Users/Gene/AppData/Local/Temp/RackMultipart20141130-5144-yn8i9>>, "commit"=>"Submit"}
CallHistoryUploadsController start
CallHistoryUpload.initialize start
call_history_file = Test_kiyvivzokpysxilfoftavyuftot.csv
user_id = KinteraAdmin
CallHistoryUpload.initialize end
CallHistoryUploadsController after instantiation
Completed 500 Internal Server Error in 0ms
NoMethodError (undefined method `has_key?' for nil:NilClass):
app/controllers/call_history_uploads_controller.rb:24:in `create'
Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_trace.erb (0.0ms)
Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.0ms)
Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.13/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (0.0ms)

Answer 1

Oh god, what a mess... You should use composition instead of inheritance. A first refactoring could be:
class CallHistoryUpload < SimpleDelegator
class Model < ActiveRecord::Base
has_many :call_histories, dependent: :destroy
end
def initialize(file_name, user_id)
logger.debug( 'CallHistoryUpload.initialize start')
logger.debug( " call_history_file = #{file_name}" )
logger.debug( " user_id = #{user_id}" )
super( new_model(file_name, user_id) )
logger.debug( "CallHistoryUpload.initialize end")
end
def model
__getobj__
end
def self.create(file_name, user_id)
logger.debug('CallHistoryUploadsController start')
chu = self.new(file_name, user_id)
logger.debug( 'CallHistoryUploadsController after instantiation')
logger.debug( "call_history_upload.file_name = #{chu.file_name}")
return chu
end
private
def new_model(file_name, user_id)
self.class::Model.new({
file_name: file_name,
user_id: user_id,
record_count: 0,
international_call_count: 0,
unknown_client_count: 0,
})
end
end
In the controller we change only the creation:
# POST /call_history_uploads
# POST /call_history_uploads.json
def create
#call_history_upload = CallHistoryUpload.create( params[:call_history_file].original_filename, session[:user_id] )
# rest of the code
If you use something like form_for you may want to pass the #call_history_upload.model to it.
Always try to put as little logic as possible in the controller and to encapsulate it in some object :)

Answer 2

Part of the problem seems to be that you're overriding the normal behavior of ActiveRecord::Base on initialize. An active record object allows you to populate an object's properties like so MyObject.new(property: 'value')
Either remove the initialize method from your object and instantiate your object using
file_name = params[:call_history_file].original_filename
user_id = session[:user_id]
CallHistoryUpload.new(file_name: file_name, user_id: user_id)
or
Call super from within your initialize method to allow ActiveRecord::Base to do its thing like so
def initialize(file_name, user_id)
logger.debug( "CallHistoryUpload.initialize start")
logger.debug( " call_history_file = " + file_name )
logger.debug( " user_id = " + user_id )
#record_count = 0
#international_call_count = 0
#unknown_client_count = 0
super(file_name: file_name, user_id: user_id)
logger.debug( "CallHistoryUpload.initialize end")
end
I'd recommend the first approach as it cleans up your model. If you need to assign default values on the instance of the model, I'd recommend creating a class method with a descriptive name which sets this values on the call to new doing the same assignment as on the first approach. Using an after_initialize call back would also be another option to set defaults but be aware of the consequences of it.
I'd really recommend reading the Getting Started guide to Rails if you're new and are trying to get used to Rails conventions.