un-deprecate stream-like objects

- deprecate file and replace with sendfile
- update stream to not deprecate stream-like objects

Author: urkle

CHANGELOG.md

@@ -1,7 +1,8 @@
-### 1.3.4 (Next)
+### 1.4.0 (Next)
 
 #### Features
 
+* [#1520](https://github.com/ruby-grape/grape/pull/1520): Un-deprecate stream-like objects - [@urkle](https://github.com/urkle).
 * [#2060](https://github.com/ruby-grape/grape/pull/2060): Drop support for Ruby 2.4 - [@dblock](https://github.com/dblock).
 * [#2060](https://github.com/ruby-grape/grape/pull/2060): Upgraded Rubocop to 0.84.0 - [@dblock](https://github.com/dblock).
 * Your contribution here.

README.md

@@ -3168,17 +3168,19 @@ end
 
 Use `body false` to return `204 No Content` without any data or content-type.
 
-You can also set the response to a file with `file`.
+You can also set the response to a file with `sendfile`. This works with the
+[Rack::Sendfile](https://www.rubydoc.info/gems/rack/Rack/Sendfile) middleware to optimally send
+the file through your web server software.
 
 ```ruby
 class API < Grape::API
   get '/' do
-    file '/path/to/file'
+    sendfile '/path/to/file'
   end
 end
 ```
 
-If you want a file to be streamed using Rack::Chunked, use `stream`.
+To stream a file in chunks use `stream`
 
 ```ruby
 class API < Grape::API
@@ -3188,6 +3190,26 @@ class API < Grape::API
 end
 ```
 
+If you want to stream non-file data use the `stream` method and a `Stream` object.
+This is an object that responds to `each` and yields for each chunk to send to the client.
+Each chunk will be sent as it is yielded instead of waiting for all of the content to be available.
+
+```ruby
+class MyStream
+  def each
+    yield 'part 1'
+    yield 'part 2'
+    yield 'part 3'
+  end
+end
+
+class API < Grape::API
+  get '/' do
+    stream MyStream.new
+  end
+end
+```
+
 ## Authentication
 
 ### Basic and Digest Auth

UPGRADING.md

@@ -1,6 +1,70 @@
 Upgrading Grape
 ===============
 
+### Upgrading to >= 1.4.0
+
+#### Reworking stream and file and un-deprecating stream like-objects
+
+Previously in 0.16 stream-like objects were deprecated. This release restores their functionality for use-cases other than file streaming.
+
+This release deprecated `file` in favor of `sendfile` to better document its purpose.
+
+To deliver a file via the Sendfile support in your web server and have the Rack::Sendfile middleware enabled. See [`Rack::Sendfile`](https://www.rubydoc.info/gems/rack/Rack/Sendfile).
+```ruby
+class API < Grape::API
+  get '/' do
+    sendfile '/path/to/file'
+  end
+end
+```
+
+Use `stream` to stream file content in chunks.
+
+```ruby
+class API < Grape::API
+  get '/' do
+    stream '/path/to/file'
+  end
+end
+```
+
+Or use `stream` to stream other kinds of content. In the following example a streamer class 
+streams paginated data from a database.
+
+```ruby
+class MyObject     
+  attr_accessor :result
+
+  def initialize(query)
+    @result = query
+  end
+  
+  def each
+    yield '['
+    # Do paginated DB fetches and return each page formatted
+    first = false
+    result.find_in_batches do |records|
+      yield process_records(records, first)
+      first = false
+    end
+    yield ']'  
+  end
+
+  def process_records(records, first)
+    buffer = +''
+    buffer << ',' unless first
+    buffer << records.map(&:to_json).join(',')
+    buffer
+  end
+end
+
+class API < Grape::API
+  get '/' do
+    stream MyObject.new(Sprocket.all)
+  end
+end
+```
+
 ### Upgrading to >= 1.3.3
 
 #### Nil values for structures

lib/grape.rb

@@ -206,12 +206,12 @@ module Presenters
     end
   end
 
-  module ServeFile
+  module ServeStream
     extend ::ActiveSupport::Autoload
     eager_autoload do
-      autoload :FileResponse
       autoload :FileBody
       autoload :SendfileResponse
+      autoload :StreamResponse
     end
   end
 end

lib/grape/dsl/inside_route.rb

@@ -279,23 +279,36 @@ def return_no_content
         body false
       end
 
-      # Allows you to define the response as a file-like object.
+      # Deprecated method to send files to the client. Use `sendfile` or `stream`
+      def file(value = nil)
+        if value.is_a?(String)
+          warn '[DEPRECATION] Use sendfile or stream to send files.'
+          sendfile(value)
+        elsif !value.is_a?(NilClass)
+          warn '[DEPRECATION] Use stream to use a Stream object.'
+          stream(value)
+        else
+          warn '[DEPRECATION] Use sendfile or stream to send files.'
+          sendfile
+        end
+      end
+
+      # Allows you to send a file to the client via sendfile.
       #
       # @example
       #   get '/file' do
-      #     file FileStreamer.new(...)
+      #     sendfile FileStreamer.new(...)
       #   end
       #
       #   GET /file # => "contents of file"
-      def file(value = nil)
+      def sendfile(value = nil)
         if value.is_a?(String)
-          file_body = Grape::ServeFile::FileBody.new(value)
-          @file = Grape::ServeFile::FileResponse.new(file_body)
+          file_body = Grape::ServeStream::FileBody.new(value)
+          @stream = Grape::ServeStream::StreamResponse.new(file_body)
         elsif !value.is_a?(NilClass)
-          warn '[DEPRECATION] Argument as FileStreamer-like object is deprecated. Use path to file instead.'
-          @file = Grape::ServeFile::FileResponse.new(value)
+          raise ArgumentError, 'Argument must be a file path'
         else
-          instance_variable_defined?(:@file) ? @file : nil
+          stream
         end
       end
 
@@ -318,7 +331,16 @@ def stream(value = nil)
         header 'Content-Length', nil
         header 'Transfer-Encoding', nil
         header 'Cache-Control', 'no-cache' # Skips ETag generation (reading the response up front)
-        file(value)
+        if value.is_a?(String)
+          file_body = Grape::ServeStream::FileBody.new(value)
+          @stream = Grape::ServeStream::StreamResponse.new(file_body)
+        elsif value.respond_to?(:each)
+          @stream = Grape::ServeStream::StreamResponse.new(value)
+        elsif !value.is_a?(NilClass)
+          raise ArgumentError, 'Stream object must respond to :each.'
+        else
+          instance_variable_defined?(:@stream) ? @stream : nil
+        end
       end
 
       # Allows you to make use of Grape Entities by setting

lib/grape/endpoint.rb

@@ -99,7 +99,7 @@ def initialize(new_settings, options = {}, &block)
       @block = nil
 
       @status = nil
-      @file = nil
+      @stream = nil
       @body = nil
       @proc = nil
 
@@ -271,8 +271,8 @@ def run
           # status verifies body presence when DELETE
           @body ||= response_object
 
-          # The body commonly is an Array of Strings, the application instance itself, or a File-like object
-          response_object = file || [body]
+          # The body commonly is an Array of Strings, the application instance itself, or a Stream-like object
+          response_object = stream || [body]
 
           [status, header, response_object]
         ensure

lib/grape/middleware/formatter.rb

@@ -36,9 +36,9 @@ def after
       def build_formatted_response(status, headers, bodies)
         headers = ensure_content_type(headers)
 
-        if bodies.is_a?(Grape::ServeFile::FileResponse)
-          Grape::ServeFile::SendfileResponse.new([], status, headers) do |resp|
-            resp.body = bodies.file
+        if bodies.is_a?(Grape::ServeStream::StreamResponse)
+          Grape::ServeStream::SendfileResponse.new([], status, headers) do |resp|
+            resp.body = bodies.stream
           end
         else
           # Allow content-type to be explicitly overwritten

lib/grape/serve_file/file_body.rb renamed to lib/grape/serve_stream/file_body.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Grape
-  module ServeFile
+  module ServeStream
     CHUNK_SIZE = 16_384
 
     # Class helps send file through API

lib/grape/serve_file/sendfile_response.rb renamed to lib/grape/serve_stream/sendfile_response.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module Grape
-  module ServeFile
+  module ServeStream
     # Response should respond to to_path method
     # for using Rack::SendFile middleware
     class SendfileResponse < Rack::Response

lib/grape/serve_file/file_response.rb renamed to lib/grape/serve_stream/stream_response.rb

@@ -1,22 +1,22 @@
 # frozen_string_literal: true
 
 module Grape
-  module ServeFile
-    # A simple class used to identify responses which represent files and do not
+  module ServeStream
+    # A simple class used to identify responses which represent streams (or files) and do not
     # need to be formatted or pre-read by Rack::Response
-    class FileResponse
-      attr_reader :file
+    class StreamResponse
+      attr_reader :stream
 
-      # @param file [Object]
-      def initialize(file)
-        @file = file
+      # @param stream [Object]
+      def initialize(stream)
+        @stream = stream
       end
 
       # Equality provided mostly for tests.
       #
       # @return [Boolean]
       def ==(other)
-        file == other.file
+        stream == other.stream
       end
     end
   end

lib/grape/version.rb

@@ -2,5 +2,5 @@
 
 module Grape
   # The current version of Grape.
-  VERSION = '1.3.4'
+  VERSION = '1.4.0'
 end