How to download an image file via HTTP into a temp file?

Question

I've found good examples of NET::HTTP for downloading an image file, and I've found good examples of creating a temp file. But I don't see how I can use these libraries together. I.e., how would the creation of the temp file be worked into this code for downloading a binary file?

require 'net/http'

Net::HTTP.start("somedomain.net/") do |http|
    resp = http.get("/flv/sample/sample.flv")
    open("sample.flv", "wb") do |file|
        file.write(resp.body)
    end
end
puts "Done."

Did you submit the edit correctly? I suspect not otherwise your code seems like a direct copy of your first example. — Shadwell, Aug 27 '13 at 20:14
And what happens when you replace the `open("sample.flv")...` part with the stuff you read from the Tempfile docs? — maerics, Aug 27 '13 at 20:14
Okay, so maerics' question still stands then. What have you tried so far? (I assume more than just running the code from the first example and hoping it magically works!) — Shadwell, Aug 27 '13 at 20:18

score 49 · Accepted Answer · edited Mar 29 '17 at 14:57

49

There are more api-friendly libraries than Net::HTTP, for example httparty:

require "httparty"

url = "https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/DahliaDahlstarSunsetPink.jpg/250px-DahliaDahlstarSunsetPink.jpg"

File.open("/tmp/my_file.jpg", "wb") do |f| 
  f.write HTTParty.get(url).body
end

edited Mar 29 '17 at 14:57

Benjamin Manns

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answered Aug 27 '13 at 20:18

fguillen

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Thanks; I was looking for an httparty example in binary mode like this. – Dogweather Aug 27 '13 at 20:20
3

Considering it's an image file, you might want to set `f.binmode` before starting to write to the file. – Marius Butuc Sep 10 '15 at 19:52
@MariusButuc suggestion added. – fguillen Sep 11 '15 at 13:23
add `f.close` as without it file may not get closed properly => 0B problem – equivalent8 Mar 16 '16 at 18:27
2

`f.binmode` is already covered by the file open mode `wb`. `f.close` is redundant because the `File.open` block will always close the file see http://stackoverflow.com/a/4795782/716 – roo Nov 21 '16 at 04:17

maerics · Answer 2 · 2015-09-18T19:25:54.923

17

require 'net/http'
require 'tempfile'
require 'uri'

def save_to_tempfile(url)
  uri = URI.parse(url)
  Net::HTTP.start(uri.host, uri.port) do |http|
    resp = http.get(uri.path)
    file = Tempfile.new('foo', Dir.tmpdir, 'wb+')
    file.binmode
    file.write(resp.body)
    file.flush
    file
  end
end

tf = save_to_tempfile('http://a.fsdn.com/sd/topics/transportation_64.png')
tf # => #<File:/var/folders/sj/2d7czhyn0ql5n3_2tqryq3f00000gn/T/foo20130827-58194-7a9j19>

edited Sep 18 '15 at 19:25

answered Aug 27 '13 at 20:20

maerics

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Interesting. I get an encoding error running this with ruby 2.0 inside Rails: Encoding::UndefinedConversionError: "\x89" from ASCII-8BIT to UTF-8 – Dogweather Aug 27 '13 at 20:24
@Dogweather do then `resp.body.force_encoding("ASCII-8BIT")` and try the same. – Arup Rakshit Aug 27 '13 at 20:25
5

The fix is adding "file.binmode". – Dogweather Aug 27 '13 at 20:53
Just a heads up, this won't work if the URL includes parameters, as eg. S3 authenticated urls. – fabi May 21 '19 at 08:08

score 10 · Answer 3 · edited Apr 26 '18 at 09:12

10

I like to use RestClient:

file = File.open("/tmp/image.jpg", 'wb' ) do |output|
  output.write RestClient.get("http://image_url/file.jpg")
end

edited Apr 26 '18 at 09:12

ndnenkov

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answered Jul 18 '14 at 14:50

Daniel Cukier

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score 4 · Answer 4 · answered Nov 14 '19 at 18:43

Though the answers above work totally fine, I thought I would mention that it is also possible to just use the good ol' curl command to download the file into a temporary location. This was the use case that I needed for myself. Here's a rough idea of the code:

# Set up the temp file:
file = Tempfile.new(['filename', '.jpeg'])

#Make the curl request:
url = "http://example.com/image.jpeg"
curlString = "curl --silent -X GET \"#{url}\" -o \"#{file.path}\""
curlRequest = `#{curlString}`

For my case I was trying without the ['filename', '.jpeg'] array in the new tempfile and it wasn't working. Adding it made it work. — amorimluc, Sep 06 '22 at 14:57

score 4 · Answer 5 · answered Jan 19 '21 at 10:05

If you like to download a file using HTTParty you can use the following code.

resp = HTTParty.get("https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_92x30dp.png")

file = Tempfile.new
file.binmode
file.write(resp.body)
file.rewind

Further, if you want to store the file in ActiveStorage refer below code.

object.images.attach(io: file, filename: "Test.png")

How to download an image file via HTTP into a temp file?

5 Answers5