Optional fields do not generate correct defaults in Pydantic

[calclavia]

Describe the bug
A clear and concise description of what the bug is.
Using proto v3

Marking a field as optional in Proto doesn't seem to change anything in the generated Pydantic model.

To Reproduce
.proto

syntax = "proto3";

message A {
    string a = 1;
}
message B {
    optional A a = 1;
}

Output:

class A(BaseModel):
    a: str = Field(default="")

class B(BaseModel):
    a: typing.Optional[A] = Field()

Expected behavior
This is the expected output:

class A(BaseModel):
    a: str = Field(default="")


class B(BaseModel):
    a: typing.Optional[A] = Field(default=None)

Note that without setting default = None in Pydantic, it's impossible to construct B() with no args. You have to construct it via B(a=None).

[so1n]

Thanks for the feedback, I will fix this in version 0.2.0.1.

[calclavia]

@so1n There's another bug created that's caused by the fix.

For fields such as:

repeated string a = 1;

It now generates this:

a: typing.Optional[typing.List[str]] = Field(default_factory=list, default=None)

which is not allowed in Pydantic. You cannot have default_factory and a default.

[so1n]

@so1n There's another bug created that's caused by the fix.

For fields such as:

repeated string a = 1;

It now generates this:

a: typing.Optional[typing.List[str]] = Field(default_factory=list, default=None)

which is not allowed in Pydantic. You cannot have default_factory and a default.

Please provide the Protobuf file or Message, I can't reproduce the problem at the moment

[calclavia]

@so1n Here it is:

syntax = "proto3";

message A {
    optional string a = 2;
    repeated string b = 3;
}

Output:

# This is an automatically generated file, please do not change
# gen by protobuf_to_pydantic[v0.2.0.1](https://github.com/so1n/protobuf_to_pydantic)
# Protobuf Version: 4.24.3
# Pydantic Version: 1.10.12
from google.protobuf.message import Message  # type: ignore
from pydantic import BaseModel
from pydantic import Field
import typing


class A(BaseModel):
    a: typing.Optional[str] = Field(default="")
    b: typing.Optional[typing.List[str]] = Field(default_factory=list, default=None)

It doesn't happen if you only have a single repeated field b.