How to return a pdf file from a rest api?

Question

I have setup a rest API inside a ruby on rails application, I now have a requirement to generate a PDF and return this PDF from a get request. I am looking for some advice on how to implement this feature.

Some of the requirements that I have are as follows: I can't save the file and give the end user a link to the file because the data in the file can be updated at any time. I am using the application as microservice so there isn't a front end that I can use to display the file.

So here is my thinking I would love some advice on how to implement this feature.

I would like to make a get request to a specific endpoint in the application. I expect a PDF file to be returned which I can then display to the end user.

I am currently using WickedPdf gem to generate a temporary PDF file, but I am really struggling with how the response should look.

Any advice would be much appreciated.

Do you want to force download the pdf when that get request is called? — Sajin, Mar 15 '17 at 10:47
take a look at send_data - http://apidock.com/rails/ActionController/Streaming/send_data. Is this what you are looking for? — Sajin, Mar 15 '17 at 10:52

score 5 · Answer 1 · answered Mar 15 '17 at 12:51

One way is to create a PDF file in memory and stream it to the client. I prefer this way, maybe later you will have to send PDF files via email, or just save them to some backup disk etc...

def get_pdf
  pdf = WickedPdf.new.pdf_from_string('<h1>Hello There!</h1>')
  send_data pdf, filename: 'file_name.pdf'
end

You can put the PDF generation to a different service and just call it in the controller. This provides isolation and you can test it separately.

Also you can debug the endpoint response with HTTPie http get http://localhost:3000/invoices/1/get_pdf

Rails will set all the necessary HTTP response headers:

Content-Disposition: attachment; filename="file_name.pdf"
Content-Length: 5995
Content-Transfer-Encoding: binary
Content-Type: application/pdf

So when the user clicks on a link that points to the endpoint, most probably the download dialog will pop up because of the Content-Disposition: attachment; header

Other solution is to render the get_pdf.html as PDF and send back to the client:

def get_pdf
  render pdf: "file_name"
end

But in this case the Content-Disposition header will be inline, which means the browser will open the pdf (if it can read PDF format) instead of offering to download it.

score 0 · Answer 2 · answered Mar 15 '17 at 10:06

0

Upload pdf to Amazon s3 and generate link then get pdf link in apis.

answered Mar 15 '17 at 10:06

puneet18

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This is the easiest but we don't want to save it rather generate when called – Andrew_tainton Mar 15 '17 at 12:29
create route, call controller action and generate pdf using wickedpdf and pass that url or route in api. – puneet18 Mar 15 '17 at 12:42

score 0 · Answer 3 · answered May 18 '17 at 19:54

I don't know if you still need this, but for anyone in the future I found a nice solution:

pdf = WickedPdf.new.pdf_from_string(render_to_string "entradas/entradaspdf.pdf.erb")
send_data pdf, filename: "bergha.pdf", disposition: "inline"

I'm loading my pdf-html-view based template through "render_to_string" ruby method which returns the view contents in string. Then WickedPdf converts it to a pdf binary, and finally save that to "pdf" var.

Finally instead of "render" I use the "send_data" method, where first parameter is the output data (my pdf var), second is the filename of the output data, and third (optional) is to change Content-Disposition header to tell browser whether to load the file (inline) or just download it (attachment).
Hope it works, it does just fine for me

How to return a pdf file from a rest api?

3 Answers3