Ruby parsing XML: no implicit conversion of String into Integer - ruby

Question

I'm working on a Sinatra application that pulls in a list of dates through an XML file and then creates an hash of all the dates.
I'm running into a strange issue that's happening when I'm pulling the id and assigning it to a variable.
The error I'm getting is:
no implicit conversion of String into Integer and it's being thrown on the event_date_id = event_date["date_id"] line. I have almost identical method in my code and it's working just fine. When I puts event_date['date_id'] it gives me the correct numerical date_id.
Just in case it helps, the class of the event_date['date_id'] is REXMLUtiliyNodeString, same as the id field in the other method. If I try to event_date['date_id'].to_i it gives breaks at that point.
def get_dates(event_id)
url = "some_url_to_some_xml"
puts '==================='
puts "Pulling in #{url}"
puts '==================='
date_xml = Crack::XML.parse(open(url))
dates = {}
date_xml['document']['date'].each do | event_date |
event_date_id = event_date['date_id']
single_date = {
'date_id' => event_date_id,
'date_start' => event_date['datestart'],
'date_end' => event_date['dateend'],
'date_live' => event_date['live'],
'time_start' => event_date['timestart'],
'time_end' => event_date['timestart'],
'date_available' => event_date['date_available']
}
dates.merge!( event_date_id => single_date )
end
return dates
end
Here is the xml format:
<document>
<date>
<date_id>881908</date_id>
<live>y</live>
<datestart>2017-08-14</datestart>
<dateend>2017-08-15</dateend>
<timestart>13:00</timestart>
<timeend>0:00</timeend>
<date_available>10000</date_available>
</date>
<document>
I have a feeling this is something really simple but I'm wracking my brains trying to figure it out. If anyone could shed some light on this, I'd definitely appreciate it.
Edit 1: When I run the code in irb, it does indeed work without error. Somewhere, somehow it seems Sinatra, Rack or Shotgun are getting in the way.

Answer 1

I have found the cause of my issue. It only occurs when I'm parsing an xml file with one entry for date/event whatever.
This question explains the exact issue I was having and the answer includes a work around that worked for me.
if(!date_xml['document']['date'].is_a?(Array))
date_xml['document']['date'] = [ date_xml['document']['date'] ]
end

Answer 2

This message occurs when you try to use a string index to look up a value in an array.
2.0.0p353 :001 > results = [""]
=> [""]
2.0.0p353 :002 > results["x"]
TypeError: no implicit conversion of String into Integer
from (irb):2:in `[]'
from (irb):2
from /home/jeff/.rvm/rubies/ruby-2.0.0-p353/bin/irb:12:in `<main>'
Since arrays can only be accessed by integer indexes, Ruby attempts to transform your key name into an integer, and fails because it doesn't know what number should be used to represent arbitrary string data. Hence the message "no implicit conversion of String into Integer".
If you're experiencing this, the answer is to fix your code so that it doesn't try to access an array like a hash. If you're importing from XML or JSON data on the assumption that the key desired is always there and will always be imported, but you're still getting this, your assumption is wrong; the data is not formatted as expected. Either fix the data or fix the code to handle the differing format.

Answer 3

I randomly stumbled upon what may be a better answer to this question, although I am very inexperienced so I think it needs to be verified.
I had an identical issue and saw that much of the trouble seems to be because I was returning a somewhat confusing array of one object.
Once I added ".first" to my query, I was able to retrieve my intended attribute.
response = File.open('ncaa_bb_schedule.xml')
doc = Nokogiri::XML(response)
doc.remove_namespaces!
doc.xpath('//game').each do |game|
h = game.xpath('home').first
p h['id']
end
But my original query, shown here
response = File.open('ncaa_bb_schedule.xml')
doc = Nokogiri::XML(response)
doc.remove_namespaces!
doc.xpath('//game').each do |game|
h = game.xpath('home')
p h['id']
end
end
was giving me the same error: "TypeError: no implicit conversion of String into Integer." Hope that helps somebody as it is much shorter than the aforementioned workaround.