Ruby Sequel MySQL Insert Error - mysql

Question

I am learning Ruby and I am using the Sequel gem to handle my model. but I keep running into an error I can't seem to hunt down. The thing that doesn't make sense is that is it failing on an insert because a field doesn't exist in a table that I am inserting into. However, I am not attempting to use the field that doesn't exist.
Here is my error:
0
{:id=>5, :name=>"barcelona"} : {:id=>4, :name=>"berlin"}
/Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/mysql.rb:175:in `query': Mysql::Error: Unknown column 'name' in 'field list' (Sequel::DatabaseError)
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/mysql.rb:175:in `block in _execute'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/database/logging.rb:33:in `log_yield'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/mysql.rb:175:in `_execute'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/shared/mysql_prepared_statements.rb:34:in `block in execute'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/database/connecting.rb:250:in `block in synchronize'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/connection_pool/threaded.rb:98:in `hold'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/database/connecting.rb:250:in `synchronize'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/shared/mysql_prepared_statements.rb:34:in `execute'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/adapters/mysql.rb:160:in `execute_insert'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/dataset/actions.rb:927:in `execute_insert'
from /Users/username/.rvm/gems/ruby-2.2.0/gems/sequel-4.20.0/lib/sequel/dataset/actions.rb:336:in `insert'
from travellingAmerican.rb:70:in `addDist'
from travellingAmerican.rb:64:in `block (2 levels) in addLocations'
from travellingAmerican.rb:61:in `each'
from travellingAmerican.rb:61:in `block in addLocations'
from travellingAmerican.rb:58:in `each'
from travellingAmerican.rb:58:in `addLocations'
from travellingAmerican.rb:93:in `<main>'
Here is models.rb:
#Database
require 'sequel'
def create
DB.create_table(:locations) do
primary_key :id
String :name, :unique=>true
end
DB.create_table(:distances) do
primary_key :id
foreign_key :to, :locations
foreign_key :from, :locations
Float :miles, :default=>-1
TrueClass :valid, :default=>0
unique [:to, :from]
end
end
def drop
begin
DB.drop_table(:distances)
rescue
puts "Couldn't drop Distances"
end
begin
DB.drop_table(:locations)
rescue
puts "Couldn't drop locations"
end
end
DB = Sequel.connect(:adapter=>'mysql', :host=>'myHost', :user=>'myUser', :password=>'myPass', :database=>'myDB')
if __FILE__ == $PROGRAM_NAME
puts "Will Execute"
drop
create
puts "Done Executing"
end
Now the file the error is actually in, travellingAmerican.rb:
#Traveling American
require './models.rb'
require 'json'
def urlCreator(cities)
urls = []
rootUrl = "https://maps.googleapis.com/maps/api/distancematrix/json?"
origin = "origins="
dest = "destinations="
key = "myApiKey"
cities.each do |city|
city = city.gsub(/[" "]/, '+')
newOrigin = origin + city + "|"
newDest = dest
cities.each do |inCity|
newDest += inCity + "|"
end
newUrl = rootUrl + newOrigin + "&" + newDest + "&" + key
urls.push(newUrl)
end
urls
end
def processFile(file)
cities = []
File.readlines(file).each do |line|
line = line.strip
if line.count(",") == 1
line = line.split()
else
cities.push(line)
end
end
return cities
end
def addLocations(cities)
cities.each do |city|
begin
DB[:locations].insert(:name => city.downcase)
rescue Sequel::UniqueConstraintViolation
puts "Duplicate, not added"
end
end
allLocs = DB[:locations].where(:name => cities).order(:name).all
#if you puts allLocs it works beautifully
for i in 0...allLocs.length
puts i
toLoc = allLocs[i]
for j in (i+1)...allLocs.length
fromLoc = allLocs[j]
puts toLoc.to_s + " : " + fromLoc.to_s
#If you comment out the line below everything runs fine, minus the insertion obviously
addDist(toLoc, fromLoc)
end
end
end
def addDist(tos, froms)
#the line with the error
DB[:distances].insert(:to=>tos, :from=>froms)
end
if __FILE__ == $PROGRAM_NAME
popSize = -1
file = ""
count = 0
ARGV.each do|arg|
if count == 0
popSize = arg.to_i
else
file = arg
end
count += 1
end
if popSize == -1 or file == ""
abort("Usage: ruby travellingAmerican.rb popSize cityList")
end
cities = processFile(file)
addLocations(cities)
puts urlCreator(cities)
end
Lastly here is cities.csv if you would like to run this on your own machine:
San Diego
Munich
Paris
Berlin
Barcelona
Monte Carlo
Cinque Terre
Turin
Milan
Florence
Rome
Venice
To run this on your own machine just execute ruby travellingAmerican.rb 1000 cities.csv in a shell.
I hope I have provided enough info for everyone! Thanks for looking.

Answer 1

There are some problems I detected:
Here you add the cities with downcase:
cities.each do |city|
begin
DB[:locations].insert(:name => city.downcase)
rescue Sequel::UniqueConstraintViolation
puts "Duplicate, not added"
end
end
The you read them in a Hash:
allLocs = DB[:locations].where(:name => cities).order(:name).all
The condition is without the downcase! So you get no result.
You could do:
allLocs = DB[:locations].where(:name => cities.map(&:downcase)).order(:name).all
Later you use
addDist(toLoc, fromLoc)
toLoc and fromLoc are both Hashes, but the should be the key for the table cities.
This should work:
addDist(toLoc[:id], fromLoc[:id])
As an alternative you can adapt the insertion in addDist
DB[:distances].insert(:to=>tos[:id], :from=>froms[:id])
The usage of for is not ruby-like. I would use directly Sequel::Dataset#each:
selection = DB[:locations].where(:name => cities.map(&:downcase)).order(:name)
selection.each{|toLoc|
selection.each{|fromLoc|
puts toLoc.to_s + " : " + fromLoc.to_s
#If you comment out the line below everything runs fine, minus the insertion obviously
addDist(toLoc[:id], fromLoc[:id])
}
}
(You could discuss, if the where and order methods are really needed here)