XML import to PostgreSQL using Nokogiri - ruby-on-rails

Question

I would like to import an XML file from a URL using Nokogiri and save it to my PostgreSQL database.
In my schema.rb I have the following table:
create_table "centres", force: :cascade do |t|
t.string "name"
t.string "c_type"
t.text "description"
t.float "lat"
t.float "long"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
Below is a sample from the file I am importing:
<facility>
<id>CG432</id>
<facility_name>Cairncry Community Centre</facility_name>
<expiration>2099-12-31T23:59:59Z</expiration>
<type>Community Centre</type>
<brief_description/>
<lat>57.1601027</lat>
<long>-2.1441739</long>
</facility>
I created the following import.rake task in lib/tasks:
require 'rake'
require 'open-uri'
require 'Nokogiri'
namespace :db do
task :xml_parser => :environment do
doc = Nokogiri::XML(open("http://sample.xml"))
doc.css('centre').each do |node|
facility_name = node.xpath("centre").text,
type = node.xpath("centre").text,
brief_description = node.xpath("centre").text,
lat = node.xpath("centre").text,
long = node.xpath("centre").text,
Centre.create(:facility_name => name, :type => c_type, :brief_description => description, :lat => lat, :long => long)
end
end
end
I tried rake db:migrate and also rake -T | grep import.

Answer 1

Your XML does not contain a <centre> element. Also there is no need to create a bunch of variables if you only intend to use them once.
doc.css('facility').each do |f|
centre = Centre.create do |c|
c.facility_name = node.css("facility_name").first.text
c.type = node.css("type").first.text
c.brief_description = node.css("brief_description").first.text
c.lat = node.css("lat").first.text
c.long = node.css("long").first.text
end
end
A more elegant way to do this if the selectors match up with your attributes is:
KEYS = ["facility_name", "type", "brief_description", "lat", "long"]
doc.css('facility').each do |f|
values = KEYS.map { |k| node.css(k).first.text }
Centre.create(Hash[*KEYS.zip(values).flatten])
end
An explaination on how this works can be found at: http://andywenk.github.io/programming/2014/06/27/ruby-create-a-hash-from-arrays/