rails send_data can't handle large file (2G+) - ruby-on-rails

My env:
Mac: 10.12.4
Memory: 16G
ruby: 2.1.4
rails: 3.2.22.5
web server: thin 1.7.0
When the file size is under 2G, everything goes well.
class ItemListsController < ApplicationController
...
send_data IO.read(zip_path), :type => 'application/zip',
:disposition => 'attachment',
:filename => file_name
However, when file size is larger than 2G, exception raised:
Errno::EINVAL: Invalid argument # io_fread
I tried to use rubyzip to output stream instead:
compressed_filestream = Zip::OutputStream.write_buffer do |zos|
files.each do |file|
zos.put_next_entry file[1]
zos.write File.open(file[0], 'r').read
end
end
compressed_filestream.rewind
send_data compressed_filestream.read, :type => 'application/zip',
:disposition => 'attachment',
:filename => file_name
Exception raised with further detail:
Unexpected error while processing request: integer 2206004964 too big to convert to `int'
/Users/karl/.rvm/gems/ruby-2.1.4#hcsvlab/gems/eventmachine-1.0.3/lib/em/connection.rb:328:in `send_data'
Seems send_data would read the whole file into memory then send data back.
My original plan is to find some way to provide "buffer" so send_data would read from buffer instead reading the whole file, but can't find such options in API
https://apidock.com/rails/ActionController/DataStreaming/send_data
Any idea would be greatly appreciated.
Thanks.

You might want to use send_file instead. According to the documentation:
Sends the file, by default streaming it 4096 bytes at a time. This way
the whole file doesn’t need to be read into memory at once. This makes
it feasible to send even large files. You can optionally turn off
streaming and send the whole file at once.

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I'm trying to stream a large Amazon S3 file to the browser using the Rails send_data method, however because the file is so large, the server runs out of memory and cannot complete the request.
The code looks something like this:
def download
s3_obj.read
end
def download_file
send_data(file.download, :filename => filename, :type => 'application/gzip', :disposition => 'attachment')
end
Is there a way to stream the chunks of the file with send_data so that it's a single file in the browser? the way I understand it is that send_data has to load the entire file into memory, then send all of that at once.
You should use send_file instead of send_data as it allow you to set the buffer and more option.
More information here.
UPDATE
If you want to download from S3, you can do this:
def download
data = open("S3_OBJECT_URL")
send_file data.read, filename: filename, type: "application/gzip", disposition: 'attachment', stream: 'true', buffer_size: '4096'
end
or
redirect_to s3_object.file.url

Firefox does not Show PDF File Extension on Download

I'm using rails to send a pdf back to the client and in Firefox the file extension is not showing:
My rails code looks like this:
send_data(
pdf,
:type => "application/pdf",
:disposition => "attachment; filename=transcript_#{Time.zone.now.strftime('%m-%d-%Y %H:%M')}.pdf",
# :filename => "transcript_#{Time.zone.now.strftime('%m-%d-%Y %H:%M')}.pdf"
)
I've been trying to set the file name with a combination of the :filename and :disposition key to display the correct filename in the browser. The :filename key doesn't seem to work in Firefox and the :disposition key gives me the picture above.
What do I need to change to get the pdf file extension to be shown in Firefox?
The space (inside of the time format) is throwing off the file name. You need to surround the file name in quotes.
Try this:
:disposition => "attachment; filename=\"transcript_#{Time.zone.now.strftime('%m-%d-%Y %H:%M')}.pdf\"",
^^ ^^
This behavior is explained here: http://kb.mozillazine.org/Filenames_with_spaces_are_truncated_upon_download.
The key point being that
[The space] creates an ambiguity when parsing the header for the filename when the browser has to consider the possibility of internationalized filenames. As Internet Explorer does not have to worry about this, it will parse the filename until the end of the line. Mozilla will not.
this will definitely work
send_data pdf.render, filename: 'transcript_#{Time.zone.now.strftime('%m-%d-%Y %H:%M')}.pdf',
type: 'application/pdf',
disposition: "attachment"

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First of all, allow me to wish you all happy reading this question, happy and productive new year.
Here comes the issue: I am unable to change file charset via Rails 3 send_data
I have some content generated via
xml_data = ''
x = Builder::XmlMarkup.new(:target => xml_data, :indent => 1)
which i fill then with all sort of data.
When I attempt to send this file for download using this command
send_data xml_data.encode('cp1251'),
:type => 'text/xml; charset=utf-8; header=present',
:filename => "data.xml"
it downloads just fine, but for some reason, when in Linux I request file encoding using
> file -bi data.xml
text/plain; charset=iso-8859-1
I need charset of this file to be utf-8. How can I automatically set it through Rails send_data?
Any help regarding this issue will be highly appreciated.
Thank you.
It appears that for the third party system the XML is used, all UTF-8 encoding is just fine.
In result i ended up with
send_data xml_data.encode('utf-8'),
:type => 'text/xml; charset=utf-8; header=present',
:filename => "data.xml"

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I'm trying to send a pdf back to the user but I'm having serious problem getting send_file and send_data to work. I created the pdf file as follows:
tmp = Tempfile.new('filled')
new_tmp_path = PDFPrint.fill_form_using_pdftk(template_path, tmp.path)
send_file (new_tmp_path, :filename => 'filled.pdf')
The browser prompts for a download, but the downloaded filled.pdf file has zero byte.
I have verified that new_tmp_path does contain a valid pdf (good, filled content)
I have tried this:
File.open(new_tmp_path, 'r') do |f|
send_data(f.read, :filename => "filled.pdf")
end
But this also gives me the same download->zero-byte problem, while the file on server (new_tmp_path) has perfect content.
Regards,
Try sending a simple file to see if it works
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Read this thread, I think it has everything you need.

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I'm using Rails to generate a PDF with the executable wkhtmltopdf and then using send_data to send the result back to the user as a PDF file.
view = ActionView::Base.new(ActionController::Base.view_paths, {})
html = "<h1>A heading</h1>"
pdfdata = `echo '#{html}' | #{RAILS_ROOT}/lib/pdf/wkhtmltopdf-i386 - -`
send_data pdfdata, :filename => 'readthis.pdf', :disposition => 'attachment', :type => "application/pdf"
The PDF is generated properly, but Rails complains ArgumentError (invalid byte sequence in UTF-8) from the send_data method. Changing it to send "foobar" as :type => text/html makes it work, so it's definitely got a problem with pdfdata.
I don't understand. Isn't send_data supposed to send binary data? Of course it's not valid UTF-8. Or am I missing something?
Thanks
Rails assumes UTF-8. Telling it explicitly that it is binary data solves the problem. Thanks for your help.
pdfdata.force_encoding('BINARY')
Did you inspect the variable pdfdata and check whether it is proper or not?

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