Module: VisionAPI::Multipart

Defined in:
lib/vision_api/multipart.rb

Overview

multipart/form-data encoding, written out rather than pulled in.

The gem depends on nothing but the standard library, and this is the only piece net/http does not already give us.

Constant Summary collapse

CONTENT_TYPES = 
{
  ".pdf" => "application/pdf",
  ".png" => "image/png",
  ".jpg" => "image/jpeg",
  ".jpeg" => "image/jpeg",
  ".webp" => "image/webp",
  ".tif" => "image/tiff",
  ".tiff" => "image/tiff"
}.freeze

Class Method Summary collapse

Class Method Details

.content_type_for(name) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/vision_api/multipart.rb', line 102

def content_type_for(name)
  CONTENT_TYPES.fetch(File.extname(name.to_s).downcase, "application/octet-stream")
end

.encode(fields, file) ⇒ Object

Encodes a multipart body. Returns [body, content_type].

An array value becomes repeated parts, which is how questions is meant to arrive over multipart; a hash is JSON-encoded, which is how schema arrives.



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# File 'lib/vision_api/multipart.rb', line 60

def encode(fields, file)
  boundary = "----visionapi#{SecureRandom.hex(16)}"
  body = +""

  fields.each do |name, value|
    next if value.nil?

    Array(wrap(value)).each do |item|
      body << "--#{boundary}\r\n"
      body << "Content-Disposition: form-data; name=\"#{name}\"\r\n\r\n"
      body << item
      body << "\r\n"
    end
  end

  if file
    filename, data, content_type = file
    body = body.b
    body << "--#{boundary}\r\n"
    body << "Content-Disposition: form-data; name=\"file\"; filename=\"#{filename}\"\r\n"
    body << "Content-Type: #{content_type}\r\n\r\n"
    body << data.b
    body << "\r\n"
  end

  body << "--#{boundary}--\r\n"
  [body, "multipart/form-data; boundary=#{boundary}"]
end

.resolve(file) ⇒ Object

Turns whatever the caller passed into [filename, bytes, content_type].

Accepts a path, a Pathname, an open binary IO, raw bytes, or an explicit [filename, bytes] pair. The filename is cosmetic — the server detects the type from magic bytes and ignores what we declare — but a sensible one makes multipart logs readable.



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# File 'lib/vision_api/multipart.rb', line 30

def resolve(file)
  case file
  when Array
    name, data = file
    [name.to_s, data.to_s, content_type_for(name.to_s)]
  when ->(f) { f.respond_to?(:read) }
    name = file.respond_to?(:path) ? File.basename(file.path.to_s) : "upload"
    [name, file.read, content_type_for(name)]
  when String, ->(f) { f.respond_to?(:to_path) }
    path = file.respond_to?(:to_path) ? file.to_path : file
    if path.match?(%r{\Ahttps?://}i)
      raise UsageError, "Pass a URL as file_url:, not as file:. " \
                        "file: is a path on disk, an open IO, or the bytes themselves."
    end
    return [File.basename(path), File.binread(path), content_type_for(path)] if File.file?(path)

    # Not a path on disk, so treat it as the bytes themselves — which is what a caller
    # who read the file already has in hand.
    ["upload", file, "application/octet-stream"]
  else
    raise UsageError, "file: must be a path, an open IO, bytes, or [filename, bytes]."
  end
rescue Errno::ENOENT, Errno::EACCES => e
  raise UsageError, "Could not read file: #{e.message}"
end

.wrap(value) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/vision_api/multipart.rb', line 90

def wrap(value)
  case value
  when Array then value.map { |item| item.is_a?(String) ? item : JSON.generate(item) }
  when Hash then JSON.generate(value)
  # Booleans go out as "true"/"false", not as JSON. Same body as the else branch, kept
  # separate because it is the one case a reader is likely to expect JSON encoding for.
  when true, false then value.to_s
  else value.to_s # rubocop:disable Lint/DuplicateBranch
  end
end