Fix sending File objects in nested objects in sendMediaGroup

lib/telegram/bot/client.rb

@@ -1,5 +1,4 @@
 require 'active_support/core_ext/hash/keys'
-require 'json'
 require 'httpclient'
 
 module Telegram
@@ -8,7 +7,9 @@ module Telegram
       SERVER = 'https://api.telegram.org'.freeze
       URL_TEMPLATE = '%<server>s/bot%<token>s/'.freeze
 
+      autoload :RequestBodyFormatter, 'telegram/bot/client/request_body_formatter'
       autoload :TypedResponse, 'telegram/bot/client/typed_response'
+
       prepend Async
       include DebugClient
 
@@ -35,16 +36,8 @@ module Telegram
           prepend TypedResponse
         end
 
-        # Encodes nested hashes as json.
-        def prepare_body(body)
-          body = body.dup
-          body.each do |k, val|
-            body[k] = val.to_json if val.is_a?(Hash) || val.is_a?(Array)
-          end
-        end
-
         def prepare_async_args(action, body = {})
-          [action.to_s, Async.prepare_hash(prepare_body(body))]
+          [action.to_s, Async.prepare_hash(RequestBodyFormatter.format(body))]
         end
 
         def error_for_response(response)
@@ -70,7 +63,7 @@ module Telegram
       end
 
       def request(action, body = {})
-        response = http_request("#{base_uri}#{action}", self.class.prepare_body(body))
+        response = http_request("#{base_uri}#{action}", RequestBodyFormatter.format(body))
         raise self.class.error_for_response(response) if response.status >= 300
         JSON.parse(response.body)
       end

lib/telegram/bot/client/request_body_formatter.rb

@@ -0,0 +1,48 @@
+require 'json'
+
+module Telegram
+  module Bot
+    class Client
+      # Encodes nested hashes and arrays as json and extract File objects from them
+      # to the top level. Top-level File objects are handled by httpclient.
+      # More details: https://core.telegram.org/bots/api#sending-files
+      module RequestBodyFormatter
+        extend self
+
+        def format(body, action)
+          body = body.dup
+          if action.to_s == 'sendMediaGroup'
+            body = extract_files_from_array!(body, :media)
+          end
+          body.each do |key, val|
+            body[key] = val.to_json if val.is_a?(Hash) || val.is_a?(Array)
+          end
+        end
+
+        private
+
+        def extract_files_from_array!(body, field_name)
+          field_name = [field_name.to_sym, field_name.to_s].find { |x| body.key?(x) }
+          return body unless field_name && body[field_name].is_a?(Array)
+          files = {}
+          body[field_name] = body[field_name].map { |x| extract_files_from_hash(x, files) }
+          body.merge!(files)
+        end
+
+        # Replace File objects with `attach` URIs. File objects are added into `files` hash.
+        def extract_files_from_hash(hash, files)
+          return hash unless hash.is_a?(Hash)
+          hash.transform_values do |value|
+            if value.is_a?(File)
+              arg_name = "_file#{files.size}"
+              files[arg_name] = value
+              "attach://#{arg_name}"
+            else
+              value
+            end
+          end
+        end
+      end
+    end
+  end
+end