Foxglove Schemas Protobuf

Common errors

• ModuleNotFoundError: No module named 'foxglove_schemas_protobuf.SomeSchema_pb2'

  cause The specific schema's `_pb2` file does not exist, or the schema name is misspelled.
  fix Verify the exact schema name from the Foxglove schemas repository. The Python module structure is `foxglove_schemas_protobuf.<SchemaName>_pb2` (e.g., `ImageAnnotation_pb2`). Ensure the package is correctly installed.

• google.protobuf.message.DecodeError: Truncated message

  cause Attempting to deserialize an incomplete, corrupted, or incompatible (e.g., non-protobuf or wrong schema type) byte string.
  fix Ensure the input byte string is a complete and valid serialized Protobuf message for the target schema. Check the source of the data for corruption or mismatch. Verify that both sender and receiver are using compatible schema versions.

• AttributeError: 'FrameTransform' object has no attribute 'old_field_name'

  cause You are attempting to access a field that no longer exists or has been renamed in the version of `foxglove-schemas-protobuf` you are using, or you are trying to parse data from a newer schema version with an older client.
  fix Update your code to reflect the current schema definition by consulting the Foxglove schema documentation or upgrading your `foxglove-schemas-protobuf` package and re-evaluating the available fields. Alternatively, ensure the data being deserialized matches the expected schema version.

Warnings

• gotcha The `foxglove-schemas-protobuf` Python package may lag behind schema updates in other Foxglove SDK languages (TypeScript, C++, Rust). If you're working with the latest schema definitions in other environments, ensure your Python package version is compatible or sufficiently recent.
  Fix: Regularly check PyPI for new versions of `foxglove-schemas-protobuf` and update your `requirements.txt`. Consult the Foxglove schemas GitHub repository for the latest schema definitions across all languages.
• gotcha Incompatibility with the `protobuf` library version. Protobuf generated code is sensitive to the version of the `protobuf` runtime library installed. Mismatched versions can lead to serialization/deserialization errors or unexpected behavior.
  Fix: Ensure your installed `protobuf` library version is compatible with the `foxglove-schemas-protobuf` package. Typically, `pip install foxglove-schemas-protobuf` will install a compatible `protobuf` version, but if you have existing protobuf installations, check for conflicts (`pip check`).
• gotcha Schema definition changes between `foxglove-schemas-protobuf` versions. While Protobuf is designed for backward compatibility, changes like renaming fields, altering field types, or modifying enum values can lead to `AttributeError` during access or `DecodeError` during deserialization if an older client tries to parse data from a newer schema (or vice-versa).
  Fix: Always pin exact versions for `foxglove-schemas-protobuf` in your project. When upgrading, test thoroughly and review the Foxglove schema changelog for breaking or compatibility-affecting changes. Use default values for optional fields to enhance robustness.

Install

• pip install foxglove-schemas-protobuf Install latest version

Imports

• FrameTransform
  wrong:

  import foxglove_schemas_protobuf.FrameTransform

  correct:

  from foxglove_schemas_protobuf.FrameTransform_pb2 import FrameTransform

  Generated protobuf messages are typically within a `_pb2` module.
• Timestamp
  wrong:

  from protobuf.timestamp_pb2 import Timestamp

  correct:

  from google.protobuf.timestamp_pb2 import Timestamp

  Common protobuf types like Timestamp are part of the `google.protobuf` package, not directly from `foxglove_schemas_protobuf`.

Quickstart

This example demonstrates how to create, serialize, and deserialize a `FrameTransform` message using the `foxglove-schemas-protobuf` library. It includes importing the specific message class and a common Google Protobuf type like `Timestamp`.

from foxglove_schemas_protobuf.FrameTransform_pb2 import FrameTransform
from google.protobuf.timestamp_pb2 import Timestamp

# Create a Timestamp
ts = Timestamp()
ts.seconds = 1678886400  # Example: March 15, 2023 12:00:00 PM UTC
ts.nanos = 123456789

# Create a FrameTransform message
transform = FrameTransform(
    timestamp=ts,
    parent_frame_id="base_link",
    child_frame_id="tool0",
    translation_x=1.0,
    translation_y=0.5,
    translation_z=0.2,
    rotation_x=0.0,
    rotation_y=0.0,
    rotation_z=0.0,
    rotation_w=1.0
)

# Serialize to bytes
serialized_data = transform.SerializeToString()
print(f"Serialized FrameTransform data length: {len(serialized_data)} bytes")

# Deserialize from bytes
deserialized_transform = FrameTransform()
deserialized_transform.ParseFromString(serialized_data)

print(f"\nDeserialized Parent frame: {deserialized_transform.parent_frame_id}")
print(f"Deserialized Child frame: {deserialized_transform.child_frame_id}")
print(f"Deserialized Timestamp: {deserialized_transform.timestamp.seconds}.{deserialized_transform.timestamp.nanos}")

assert deserialized_transform.parent_frame_id == "base_link"
assert deserialized_transform.translation_x == 1.0