TypeError：没有将String隐式转换为Integer

Question

I am trying to parse an open data XML file from the internet into my rails database. Following is the code which should parse it:

require 'rake' 
require 'open-uri' 
namespace :db do 
  task :xml_parser => :environment do 
    doc = Nokogiri::XML(open("https://dl.dropboxusercontent.com/u/21695507/openplaques/gb_20151004.xml")) 
    doc.css('plaque').each do |node| 
      children = node.children 
      Plaque.create(
        :title => children.css('title').inner_text,
        :subject => children.css('subjects').inner_text,
        :colour => children.css('colour').inner_text,
        :inscription => children.css('inscription raw').inner_text,
        :latitude => children.css('geo')["latitude"].text,
        :longitude => children.css('geo')["longitude"].text,
        :address => children.css('address').inner_text,
        :organisation => children.css('organisation').inner_text,
        :date_erected => children.css('date_erected').inner_text
      )
    end
  end
end

And here is the schema:

create_table "plaques", force: :cascade do |t|
  t.string   "title"
  t.string   "subject"
  t.string   "colour"
  t.text     "inscription"
  t.string   "latitude"
  t.string   "longitude"
  t.text     "address"
  t.text     "organisation"
  t.string   "date_erected"
  t.datetime "created_at",   null: false
  t.datetime "updated_at",   null: false
end

I run rake db:xml_parser and I get the following error:

TypeError: no implicit conversion of String into Integer

Below is a sample from the XML file I am trying to parse.

<plaque uri="http://openplaques.org/plaques/4856" machine_tag="openplaques:id=4856" created_at="2010-11-26T13:58:23+00:00" updated_at="2011-06-28T17:00:01+01:00">
  <title>Arthur Linton blue plaque</title>
  <subjects>Arthur Linton</subjects>
  <colour>blue</colour>
  <inscription>
    <raw>
      World Champion Cyclist 1895 lived here Arthur Linton 1872-1896
    </raw>
    <linked>
      World Champion Cyclist 1895 lived here <a href="/people/2934">Arthur Linton</a> 1872-1896
    </linked>
  </inscription>
  <geo reference_system="WGS84" latitude="51.7005" longitude="-3.4251" is_accurate="true" />
  <location>
    <address>Sheppard's Pharmacy, 218 Cardiff Road</address>
    <locality uri="http://0.0.0.0:3000/places/gb/areas/aberaman/plaques">Aberaman</locality>
    <country uri="http://0.0.0.0:3000/places/gb">United Kingdom</country>
  </location>
  <organisation uri="http://0.0.0.0:3000/organisations/rhondda_cynon_taf_council">Rhondda Cynon Taf Council</organisation>
  <date_erected>2009-10-26</date_erected>
  <person uri="http://0.0.0.0:3000/people/2934">Arthur Linton</person>
</plaque>

Answer 1

I don't think the error is in the schema or the Place.create(...) content . I think it's the way you are fetching data out of Nokogiri. some_node.css("some-selector") is going to return a set of multiple nodes that match the criteria. It may so happen that the number of nodes is 1 (or 0), so your .inner_text call works.

I believe your issue is on the two lines for fetching latitude and longitude:

:latitude => children.css('geo')["latitude"].text,
:longitude => children.css('geo')["longitude"].text,

children.css('geo') will return a set of nodes, in this case it's similar to a single element array [geo] . However, your call to ["latitude"] is like asking an array for it's latitude -th element... which doesn't make sense. Concretely,

a = ["a", "b", "c", "d"]
a[1] # => "b"
a["longitude"] # => what?!?, or TypeError: no implicit conversion of String into Integer

What I would do to get your lat and long values, is first pull out the first element from the css("geo") search. Then, call attributes to get the attributes hash. Then , you can fetch via string for "latitude" and "longitude" , and finally, you need to call .value to get the text value. In full,

:latitude => children.css('geo').first.attributes["latitude"].value,
:longitude => children.css('geo').first.attributes["longitude"].value,

Answer 2

There was a simpler solution, which worked perfectly!

require 'rake' 
require 'open-uri'

namespace :db do 
    task :xml_parser => :environment do 
        doc = Nokogiri::XML(open("https://dl.dropboxusercontent.com/u/21695507/openplaques/gb_20151004.xml")) 
        doc.css('plaque').each do |node| 
                title = node.xpath("plaque").text,
                subject = node.xpath("plaque").text,
                colour = node.xpath("plaque").text,
                inscription = node.xpath("plaque").text,
                latitude = node.xpath("plaque").text,
                longitude = node.xpath("plaque").text,
                address = node.xpath("plaque").text,
                organisation = node.xpath("plaque").text,
                date_erected = node.xpath("plaque").text

                Plaque.create(:title => title, :subject => subject, :colour => colour, :inscription => inscription, :latitude => latitude, :longitude => longitude, :address => address, :organisation => organisation, :date_erected => date_erected)
            end
        end
    end