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File Upload

File uploads can be accessed from request params like env.params.files["filename"].

It has 5 useful methods to get the job done!

  • tmpfile: This is the temporary file for file upload. Useful for saving or manipulating the upload file.
  • tmpfile_path: File path of tmpfile.
  • filename: File name of the file upload. (logo.png, images.zip e.g)
  • meta: Meta information for the file upload.
  • headers: Request headers for the file upload.

Here’s a fully working sample for reading an image file upload with key image1 and saving it under public/uploads.

post "/upload" do |env|
  file = env.params.files["image1"].tmpfile
  file_path = ::File.join [Kemal.config.public_folder, "uploads/", file.filename]
  File.open(file_path, "w") do |f|
    IO.copy(file, f)
  end
  "Upload ok"
end

You can test this with below curl command.

curl -F "image1=@/Users/serdar/Downloads/kemal.png" http://localhost:3000/upload