ruby - Download an image from a URL? -

i trying use http::get download image of google chart url created.

this first attempt:

failures_url  = [title, type, data, size, colors, labels].join("&")  require 'net/http'  net::http.start("http://chart.googleapis.com") { |http|   resp = http.get("/chart?#{failures_url")   open("pie.png" ,"wb") { |file|     file.write(resp.body)   } } 

which produced empty png file.

for second attempt used value stored inside failure_url inside http.get() call.

require 'net/http'  net::http.start("http://chart.googleapis.com") { |http|   resp = http.get("/chart?chtt=builds+in+the+last+12+months&cht=bvg&chd=t:296,1058,1217,1615,1200,611,2055,1663,1746,1950,2044,2781,1553&chs=800x375&chco=4466aa&chxl=0:|jul-2010|aug-2010|sep-2010|oct-2010|nov-2010|dec-2010|jan-2011|feb-2011|mar-2011|apr-2011|may-2011|jun-2011|jul-2011|2:|months|3:|builds&chxt=x,y,x,y&chg=0,6.6666666666666666666666666666667,5,5,0,0&chxp=3,50|2,50&chbh=23,5,30&chxr=1,0,3000&chds=0,3000")   open("pie.png" ,"wb") { |file|     file.write(resp.body)   } } 

and, reason, version works though first attempt had same data inside http.get() call. know why is?

solution:

after trying figure why happening found "how download binary file on http?".

one of comments mentions removing http:// in net::http.start(...) call otherwise won't succeed. sure enough after did this:

failures_url  = [title, type, data, size, colors, labels].join("&")  require 'net/http'  net::http.start("chart.googleapis.com") { |http|   resp = http.get("/chart?#{failures_url")   open("pie.png" ,"wb") { |file|     file.write(resp.body)   } } 

it worked.

i'd go after file using ruby's open::uri:

require "open-uri"  file.open('pie.png', 'wb') |fo|   fo.write open("http://chart.googleapis.com/chart?#{failures_url}").read  end 

the reason prefer open::uri handles redirects automatically, when google makes change back-end , tries redirect url, code handle magically. handles timeouts , retries more gracefully if remember right.

if must have lower level control i'd @ 1 of many other http clients ruby; net::http fine creating new services or when client doesn't exist, i'd use open::uri or besides net::http until need presents itself.

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the url:

http://chart.googleapis.com/chart?chtt=builds+in+the+last+12+months&cht=bvg&chd=t:296,1058,1217,1615,1200,611,2055,1663,1746,1950,2044,2781,1553&chs=800x375&chco=4466aa&chxl=0:|jul-2010|aug-2010|sep-2010|oct-2010|nov-2010|dec-2010|jan-2011|feb-2011|mar-2011|apr-2011|may-2011|jun-2011|jul-2011|2:|months|3:|builds&chxt=x,y,x,y&chg=0,6.6666666666666666666666666666667,5,5,0,0&chxp=3,50|2,50&chbh=23,5,30&chxr=1,0,3000&chds=0,3000 

makes uri upset. suspect seeing characters should encoded in urls.

for documentation purposes, here uri says when trying parse url as-is:

uri::invalidurierror: bad uri(is not uri?) 

if encode uri first, successful parse. testing further using open::uri shows able retrieve document @ point , returns 23701 bytes.

i think appropriate fix problem if of characters not acceptable uri and out of rfc.

just information, addressable::uri gem great replacement built-in uri.