Skip to main content

From FastAPI

This page explains how to convert an existing FastAPI application to an ODP Python Package, without changing any code.

All that's required is defining the entry point in pyproject.toml, directed to an instance of either, fastapi.FastAPI or fastapi.APIRouter.

tip

If you are already familiar with FastAPI, this is an excellent way to get started making OpenBB Python Package extensions.

Each API route (GET or POST) will be added to the obb Python package under the assigned name - i.e, obb.my_app.some_function - and will be an equivalent to the REST API endpoint. The resulting app will be an independent module that does not require a server. They will combine and operate like any other ODP router.

Add Dependency​

Add openbb-core (version pinning is not recommended, use the latest or >=1.5.5) to the project's dependencies.

info

If not already in your environment, this will introduce Numpy, Pandas, and Uvicorn.

Entry Point​

In, pyproject.toml, add a section where the object to the right of the colon is the configured instance of FastAPI or APIRouter.

ODP Python uses Poetry as the build tool, but you can use any PEP 517-compliant build backend.

Poetry​

[tool.poetry.plugins."openbb_core_extension"]
my_app = "my_package.app:app"

Standard​

[project.entry-points."openbb_core_extension"]
my_app = "my_package.app.some_router:router"
note

Factory functions are not supported. A configured instance must exist on package initialization.

Install​

The extension must be installed for it to be recognized, use your preferred method of installation. Installing as editable is recommended for development and testing.

pip install -e .

Build​

The API can be started immediately; but, to use as a Python package, the static assets must be built.

From the command line, enter:

openbb-build

Import​

Upon completion, it is ready to use. Import the package with:

from openbb import obb

print(obb.my_app)

Known Limitations​

The Python interface will be nearly identical to its REST equivalent, with some notable differences and technical limitations.

Primarily, the client/server relationship does not exist within the Python interface.

Auth Hooks​

  • Authorization hooks will not be injected into the Python static assets, functions are expected to operate without authorization.

Dependency Injections​

  • Request-bound dependnecies, or those returning None, will not be injected.

  • Command execution may fail where endpoints require access to the Request or Headers.

    • Additional handling may be required if endpoint code explicitly accesses these objects as locals.

  • All other dependencies are injected into the static assets as locals.

Streaming Endpoints​

  • Websockets are not currently supported. They will still be part of the REST API, but no Swagger docs will be generated, and they will be excluded from the Python interface.

  • Streaming responses (one-way communication) will work, but are not officially supported and may have unexpected outcomes.

Multi-Method API Routes​

  • API routes with multiple methods (e.g., /my_app/some_function has both GET and POST operations) may not generate correctly.
    • Consider implementing the methods as API path parameters.

Tips & Workarounds​

If you are having trouble building the static assets for a full application, consider targeting individual routers or wrapping functions in an instance of fastapi.APIRouter. This will help isolate and identify any problematic endpoints.

Rich metadata for each function will be generated and stored under obb.reference. Parameters and Returns sections of docstrings will be automatically generated from model definitions and annotations. For best results, use descriptive Pydantic models.

Troubleshooting​

Some issues may be resolved by installing the latest version of openbb-core.

If openbb-build results in an error and does not complete, check the error message for clues. For a verbose output, set the environment variable, OPENBB_DEBUG_MODE='1' and run it again.

Encountered errors may be related to module imports, function signatures, docstrings, or type annotations.

If openbb-build succeeds, and you encounter an import error, after from openbb import obb, the static assets may have been corrupted. Enable debug mode, run openbb-build again and inspect the final result.

If build and import were successful but an error occurs on accessing the application property, there may have been a linting error. Try, pip install -U ruff black, and then run openbb-build again. If it persists, make note of the complete error and inspect the static assets. Adjust function annotations and types to further diagnose.

Static Assets Location​

You can inspect the resulting files, which are found in the site-packages folder of the environment. The relative path is:

/site-packages/openbb/package/

If the issue cannot be resolved with changes to your code, please open an issue on GitHub with the full error messages, original vs. generated snippets, along with any other environment and platform context.

On this page