Generate proper multipart body

lib/httparty/request/body.rb

@@ -17,9 +17,27 @@ module HTTParty
         end
       end
 
+      def boundary
+        @boundary ||= "------------------------c772861a5109d5ef"
+      end
+
       private
 
       def generate_multipart
+        normalized_params = params.flat_map { |key, value| HashConversions.normalize_keys(key, value) }
+
+        multipart = normalized_params.inject('') do |memo, (key, value)|
+          memo += "--#{boundary}\n"
+          memo += "Content-Disposition: form-data; name='#{key}'"
+          memo += "; filename='#{File.basename(value)}'" if file?(value)
+          memo += "\n"
+          memo += "Content-Type: application/octet-stream\n" if file?(value)
+          memo += "\n"
+          memo += file?(value) ? value.read : value
+          memo += "\n"
+        end
+
+        multipart += "--#{boundary}--\n"
       end
 
       def multipart?
@@ -39,7 +57,7 @@ module HTTParty
       end
 
       def file?(object)
-        object.respond_to?(:path) && object.respond_to?(:read)
+        object.respond_to?(:path) && object.respond_to?(:read) # add memoization
       end
 
       def includes_hash?(object)
@@ -54,10 +72,6 @@ module HTTParty
         end
       end
 
-      def boundary
-        @boundary ||= "--------------------------#{SecureRandom.urlsafe_base64(12)}"
-      end
-
       attr_reader :params, :query_string_normalizer, :options
     end
   end

spec/httparty/request/body_spec.rb

@@ -0,0 +1,50 @@
+require_relative '../../spec_helper'
+
+RSpec.describe HTTParty::Request::Body do
+  describe '#call' do
+    subject { described_class.new(params).call }
+
+    context 'when params is string' do
+      let(:params) { 'name=Bob%20Jones' }
+
+      it { is_expected.to eq params }
+    end
+
+    context 'when params is hash' do
+      let(:params) { { people: ["Bob Jones", "Mike Smith"] } }
+      let(:converted_params) { "people[]=Bob%20Jones&people[]=Mike%20Smith"}
+
+      it { is_expected.to eq converted_params }
+
+      context 'when params has file' do
+        let(:params) do
+          {
+            user: {
+              avatar: File.open('spec/fixtures/tiny.gif'),
+              first_name: 'John',
+              last_name: 'Doe'
+            }
+          }
+        end
+        let(:multipart_params) do
+          "--------------------------c772861a5109d5ef\n" \
+          "Content-Disposition: form-data; name='user[avatar]'; filename='tiny.gif'\n" \
+          "Content-Type: application/octet-stream\n" \
+          "\n" \
+          "GIF89a\u0001\u0000\u0001\u0000\u0000\xFF\u0000,\u0000\u0000\u0000\u0000\u0001\u0000\u0001\u0000\u0000\u0002\u0000;\n" \
+          "--------------------------c772861a5109d5ef\n" \
+          "Content-Disposition: form-data; name='user[first_name]'\n" \
+          "\n" \
+          "John\n" \
+          "--------------------------c772861a5109d5ef\n" \
+          "Content-Disposition: form-data; name='user[last_name]'\n" \
+          "\n" \
+          "Doe\n" \
+          "--------------------------c772861a5109d5ef--\n"
+        end
+
+        it { is_expected.to eq multipart_params }
+      end
+    end
+  end
+end