ConJobs: Part 1 - Program your receipt printer

Transcription

1 ConJobs: Part 1 - Program your receipt printer Step 1: Prepare thermal printer Cut wires and connect the power to the printer. Screw the wires down from the power adapter. Check that the green light flashes, then place paper inside. Step 2: Connect thermal printer to Raspberry Pi For connecting the Pi to the printer, use this guide: Then plug in printer wires to Raspberry Pi GPIO pins Step 3: Set up Raspberry Pi to control thermal printer a. Install the necessary libraries: sudo apt-get install python-serial sudo apt-get install python-imaging-tk b. Give the serial port permission to dialout output: sudo usermod -a -G dialout pi c. Edit sudo nano /boot/cmdline.txt Replace dwc_otg.lpm_enable=0 console=ttyama0, kgdboc=ttyama0, console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait with dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait d. Remove last line of /etc/inittab and reboot pi e. Download python files needed to control printer from the pi sudo apt-get install git-core clone into a directory git clone git://github.com/luopio/py-thermal-printer.git f. Edit printer.py file sudo nano printer.py add #!/usr/bin/env python to top g. point to correct port /dev/ttyama0 h. Run printer.py to verify the printer prints! Step 4: Use Indeed.com API to fetch job data a. Register for indeed.com API. This will allow access to query indeed s database of jobs. b. Make queries using the Job Search API. For example, at the following URL: &q=political&l=san+francisco%2C+ca&sort=&radius=&st=&jt=&start=&limit=5&fr

2 omage=&filter=&latlong=1&co=us&chnl=&userip= &useragent=mozilla/%2f4.0%2 8Firefox%29&v=2 c. Alter the publisher query parameter value with the key granted to you. d. Alter the q query parameter value with any keyword desired. e. To further customize a search, consult the API documentation at for information about the other query parameters. f. This service will output XML data. Step 5: Set up Ruby on Rails web application to serve json data a. Create a new rails project rails new conjobs b. Heroku only uses postgresql for production, so change depencies from SQLite to PostgresQL. In Gemfile, replace gem sqlite with gem pg. In database.yml change adapter s value to postgresql c. Set up the main MVC (Model View Controller) i. rails generate controller main ii. Rails handles routes by naming conventions, so add method to main_controller.rb def new_jobs iii. Create a view of the same name - new_jobs.html.erb (erb is a ruby templating format, to easily input data to views) iv. Go to config/routes.rb to add the route: get main#newl_jobs v. Go to the gemfile and add gem http, gem crack, and gem json. These will help parse the XML, and convert the data to JSON. vi. Go to the new_jobs method and make a request to the indeed.com api, and format the data as json using the imported libraries def = = = {'jobs' rer json: JSON.pretty_generate(@output_json) def get_json_jobs url = " er= &q=political&l=san+franci sco%2c+ca&sort=&radius=&st=&jt=&start=" + get_start_value.to_s + "&limit=5&fromage=&filter=&latlong=1&co=us&c hnl=&userip= &useragent=mozilla/%2f4.0 = HTTP[:accept => = Crack::XML.parse(@job_search_xml)

3 def = [] json_jobs.each do job new_obj = {} new_obj['jobtitle'] = job['jobtitle'] new_obj['company'] = job['company'] new_obj['formattedlocation'] = job['formattedlocation'] new_obj['date'] = job['date'] new_obj['url'] = vii. End Make sure the json is being served by running a local server and testing the url /new_jobs (rails s and visit localhost:3000/new_jobs) Step 6: Set up web app for viewing all job listings a. Create the necessary model to store job data, including its attributes rails generate model job title:string company:string formattedlocation:string date:string url:string b. run rake db:reset. This drops all db files, setups the db, and adds the migrations. c. add a path to config/routes.rb. root main#all_jobs d. define a method of the same name in your routes file: def all_jobs. This is going to be the url to serve all the job postings def = Job.all def save_job(job) Job.create!(:title => job['jobtitle'], :company => job['company'], :formattedlocation => job['formattedlocation'], :date => job['date'], :url => job['url'], ) def get_start_value master_index_object = Index.first

4 master_index_object.start_index def update_index_position master_index_object = Index.first master_index_object.start_index += 5 master_index_object.save e. Create a view file of the same name: all_jobs.html.erb. Set up the view to display all the objects in variable the method is holding on too. The variables in the controller are accessible from the views, and can be referenced using html.erb templating techniques <div> do job %> <ul><%= job.title %> <li><%= job.company %></li> <li><%= job.formattedlocation %></li> <li><%= job.date %></li> <a href="<%= job.url %>" target='_blank'><li>more info</li></a> </ul> <% %> </div> f. run a local server, go to the root path and see if all_jobs are posted (rails s). If nothing is there, visit /new_jobs, which is the url that maps to the controller method that is making the request for new data, and saving the data to the Jobs database. Step 7: Set up web app for resetting database a. Go to config/routes.rb and add a route get reset => main#reset b. Go to controllers/main_controller.rb and add a new method, reset def reset clear_job_database reset_index def clear_job_database Job.destroy_all def reset_index master_job_index = Index.first master_job_index.start_index = 1 master_job_index.save c. Add a new view of the same name, to make sure the url wont error. In views/main/reset.html.erb, signal to the user the database is being wiped clean.

5 <p>database reset. Job index to 1, and all jobs destroyed.</p> d. Run a local server and visit /reset and then /all_jobs to test! (rails s) Step 8: Fetch data onto Raspberry Pi a. Create new file - conjobs.py import urllib import json import printer import requests import time NUMBER_OF_JOBS = 5 p = printer.thermalprinter(serialport= /dev/ttyama0 ) p.justify( C ) While True: result = urllib.urlopen( jobs ).read() data = json.loads(result) p.print_text( \n\n\n\n\n\n\n\n ) p.print_text( CONJOBS\n ) p.print_text( Today s hot 5 jobs\n\n\n\n ) time.sleep(2) for i in range(number_of_jobs): job = data( jobs )[i] title = %s\n % job[u jobtitle ] company = %s\n % job[u company ] formatted_location = %s\n % job[u formattedlocation ] posting_date = %s\n % job[u date ] p.print_text(title) p.print_text(company) p.print_text(formatted_location) p.print_text(posting_date) p.print_text( \n\n\n ) p.print_text( \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n ) time.sleep(86400) Step 9: Double check the programming

6 Run the file, see that it prints, check conjobs.herokuapp.com for the same jobs, with more information, including an link to apply. Enclose in box and voilà! Conjobs!