My first serious Ruby on Rails project will automatically display
information on the ETFs and mutual funds with the lowest price/book and
price/cash flow ratios and also provide other essential information for
value investors like the expense ratio, the annual portfolio turnover
rate,
and the size (in %) of the largest investment in the portfolio.
This project will be analogous to the stock screening system of Doppler
Value Investing (http://www.dopplervalueinvesting.com/screen), which
uses a
combination of Python and Drupal. Every night, the Python script
automatically scrapes data from the Smartmoney web site, calculates the
Dopeler price/book ratio for each stock, saves the information in a
*.csv
file, and copies this *.csv file to the Drupal web site so that it’s
publicly accessible. My Doppler Value Investing web site already works,
so
I’m not about to redo it. So I’ll be using Ruby on Rails for a brand
new
project instead.
Based on what I did for Doppler Value Investing, I’d be inclined to have
a
separate web site (in Ruby on Rails) and a Ruby script that produces an
output in *.csv and *.html files and copies these output files to the
Ruby
on Rails web site. However, I get the feeling that it would be better
to
integrate the web site and the number-crunching script.
Given all this, if my web site dedicated to finding the most undervalued
ETFs and mutual funds were your project instead of mine, how would you
go
about it?
On 02/16/2013 05:48 PM, Jason H., Android developer wrote:
Python script automatically scrapes data from the Smartmoney web site,
it would be better to integrate the web site and the number-crunching
script.
Given all this, if my web site dedicated to finding the most
undervalued ETFs and mutual funds were your project instead of mine,
how would you go about it?
My inclination would be to have a seperate task (cron job maybe) that
scraped the data and put it into the database. I would then have the
rails web site just calculate any needed factors from the data in the
database and sort and display the info. YMMV
On Saturday, February 16, 2013 8:52:54 PM UTC-6, Norm wrote:
My inclination would be to have a seperate task (cron job maybe) that
scraped the data and put it into the database. I would then have the
rails web site just calculate any needed factors from the data in the
database and sort and display the info. YMMV
Thanks, Norm. Yes, I use a cron job to run the
web-scraping/number-crunching Python scripts on the Doppler Value
Investing
web site, and I anticipate using a cron job to run a Ruby script every
night to run the web-scraping/number-crunching script on my ETF/mutual
fund
analysis site. Thanks for suggesting the use of a database to be
populated
by the web-scraping/number-crunching script and retrieved by the Rails
web
site.
This will be my first experience working with a web site’s database.
I would do just like I’ve done for automated tasks in several other
Rails
apps I’ve written: make a rake task for it which can be triggered via
cron
job. The rake task can simply trigger a model method to do whatever
needs
done. This keeps all code relevant to the app in the application (and
more
specifically, all code relevant to that model actually in the model),
allows you to use ActiveRecord instead of interacting directly with the
database via sql, and gives you easy access to any other functionality
you
build into your app. It also gives you the ability to more easily allow
a
user to trigger a partial update via the web site should that
functionality
ever be desired.
On Saturday, February 16, 2013 7:48:21 PM UTC-5, Jason H., Android