Object api strings return bytes instead of str [Python] #5997
Description
Given the following generated Python object api class:
class LoginInputT(object):
# LoginInputT
def __init__(self):
self.username = None # type: str
self.password = None # type: str
@classmethod
def InitFromBuf(cls, buf, pos):
loginInput = LoginInput()
loginInput.Init(buf, pos)
return cls.InitFromObj(loginInput)
@classmethod
def InitFromObj(cls, loginInput):
x = LoginInputT()
x._UnPack(loginInput)
return x
# LoginInputT
def _UnPack(self, loginInput):
if loginInput is None:
return
self.username = loginInput.Username()
self.password = loginInput.Password()
# LoginInputT
def Pack(self, builder):
if self.username is not None:
username = builder.CreateString(self.username)
if self.password is not None:
password = builder.CreateString(self.password)
LoginInputStart(builder)
if self.username is not None:
LoginInputAddUsername(builder, username)
if self.password is not None:
LoginInputAddPassword(builder, password)
loginInput = LoginInputEnd(builder)
return loginInputAnd schema:
table LoginInput {
username:string;
password:string;
}
I would expect that self.username and self.password would be of type str after a call to InitFromObj, but instead it is of type bytes. Examples in the documentation indicate that CreateString always accept a str parameter, so if the Pack function does builder.CreateString(self.username) then the opposite action in UnPack should result in str type for self.username.
Since flatbuffers schema supports string, [byte], and [ubyte] fields, I would expect that the generated Python code also honours that distinction. A library such as jsons (that generates JSON from any Python object) can not know that some fields that have type bytes should be interpreted as strings and others of type bytes are actually bytes.
The following code snippet using the jsons package, allows me to generate JSON data with the expected output types:
import os
import sys
import jsons
import flatbuffers
import MyTest.MyTest
myTest= MyTest.MyTest.MyTest.GetRootAsMyTest(buf, offs)
myTestT= MyTest.MyTest.MyTestT.InitFromObj(myTest)
def bytes_serializer(obj: bytes, detect_str: bool = False, **kwargs):
if detect_str:
try:
return obj.decode('utf-8')
except UnicodeError:
return obj
return obj
jsons.set_serializer(bytes_serializer, bytes)
return jsons.dumps(myTestT, key_transformer=jsons.KEY_TRANSFORMER_SNAKECASE, strip_privates=True, strip_nulls=True, strip_class_variables=True, strict=True, detect_str=True)