Fixed JSON encoding and decoding for lists, added empty() method

The new empty() method retrieves an empty instance of the
given object, with all the attributes set to None

telethon/utils/binary_reader.py

@@ -117,14 +117,8 @@ class BinaryReader:
             # If there was still no luck, give up
             raise TypeNotFoundError(constructor_id)
 
-        # Now we need to determine the number of parameters of the class, so we can
+        # Create an empty instance of the class, and read its values
-        # instantiate it with all of them set to None, and still, no need to write
+        result = clazz.empty()
-        # the default =None in all the classes, thus forcing the user to provide a real value
-        sig = inspect.signature(clazz.__init__)
-        params = [None] * (len(sig.parameters) - 1)  # Subtract 1 (self)
-        result = clazz(*params)  # https://docs.python.org/3/tutorial/controlflow.html#unpacking-argument-lists
-
-        # Finally, read the object and return the result
         result.on_response(self)
         return result
 

telethon_generator/tl_generator.py

@@ -133,6 +133,17 @@ class TLGenerator:
                         TLGenerator.write_onsend_code(builder, arg, tlobject.args)
                     builder.end_block()
 
+                    # Generate the empty() function, which returns an "empty"
+                    # instance, in which all attributes are set to None
+                    builder.writeln('@staticmethod')
+                    builder.writeln('def empty():')
+                    builder.writeln('"""Returns an "empty" instance (all attributes are None)"""')
+                    builder.writeln('return {}({})'.format(
+                        TLGenerator.get_class_name(tlobject),
+                        ', '.join('None' for _ in range(len(args)))
+                    ))
+                    builder.end_block()
+
                     # Write the on_response(self, reader) function
                     builder.writeln('def on_response(self, reader):')
                     # Do not read constructor's ID, since that's already been read somewhere else
@@ -163,6 +174,10 @@ class TLGenerator:
 
                     for arg in args:
                         if TLGenerator.is_tlobject(arg.type):
+                            if arg.is_vector:
+                                builder.writeln("'{0}': [{0}_item.json_encode() "
+                                                "for {0}_item in self.{0}],".format(arg.name))
+                            else:
                                 builder.writeln("'{0}': self.{0}.json_encode(),".format(arg.name))
                         else:
                             builder.writeln("'{0}': self.{0},".format(arg.name))
@@ -175,14 +190,15 @@ class TLGenerator:
                     builder.writeln('@staticmethod')
                     builder.writeln('def json_decode(json_string):')
                     builder.writeln('# Create an empty instance which will be filled with the JSON values')
-                    builder.writeln('instance = {}({})'.format(
+                    builder.writeln('instance = {}.empty()'.format(TLGenerator.get_class_name(tlobject)))
-                        TLGenerator.get_class_name(tlobject),
-                        ', '.join('None' for _ in range(len(args)))
-                    ))
                     builder.writeln('dictionary = json.loads(json_string)')
                     builder.writeln()
                     for arg in args:
                         if TLGenerator.is_tlobject(arg.type):
+                            if arg.is_vector:
+                                builder.writeln("instance.{0} = [{0}_item.json_decode() "
+                                                "for {0}_item in dictionary['{0}']]".format(arg.name))
+                            else:
                                 builder.writeln("instance.{0} = dictionary['{0}'].json_decode() if '{0}' in dictionary "
                                                 "and dictionary['{0}'] is not None else None".format(arg.name))
                         else: