fastapi-voyager 0.15.2

Visualize FastAPI application's routing tree and dependencies

Visualize your FastAPI endpoints, and explore them interactively.

Its vision is to make code easier to read and understand, serving as an ideal documentation tool.

This repo is still in early stage, it supports pydantic v2 only

visit live demo source code:composition oriented development pattern

with simple configuration it can be embedded into FastAPI.

app.mount('/voyager', 
          create_voyager(
            app, 
            module_color={'src.services': 'tomato'}, 
            module_prefix='src.services', 
            swagger_url="/docs",
            ga_id="G-XXXXXXXXVL",
            initial_page_policy='first',
            online_repo_url='https://github.com/allmonday/composition-oriented-development-pattern/blob/master',
            enable_pydantic_resolve_meta=True))

https://github.com/allmonday/composition-oriented-development-pattern/blob/master/src/main.py#L48

Plan & Raodmap

• ideas
• changelog & roadmap

Installation

pip install fastapi-voyager
# or
uv add fastapi-voyager

run with cli:

voyager -m path.to.your.app.module --server

Sub-Application mounts are not supported yet, but you can specify the name of the FastAPI application used with --app. Only a single application (default: 'app') can be selected, but in a scenario where api is attached through app.mount("/api", api), you can select api like this:

voyager -m path.to.your.app.module --server --app api

Features

For scenarios of using FastAPI as internal API integration endpoints, fastapi-voyager helps to visualize the dependencies.

It is also an architecture tool that can identify issues inside implementation, finding out wrong relationships, overfetchs, or anything else.

If the process of building the view model follows the ER model, the full potential of fastapi-voyager can be realized. It allows for quick identification of APIs that use entities, as well as which entities are used by a specific API

Given ErDiagram defined by pydantic-resolve, application level entity relationship diagram can be visualized too.

highlight nodes and links

click a node to highlight it's upperstream and downstream nodes. figure out the related models of one page, or homw many pages are related with one model.

view source code

double click a node or route to show source code or open file in vscode.

quick search

seach schemas by name and dispaly it's upstream and downstreams.

shift + click can quickly search current one

display ER diagram

ER diagram is a new feature from pydantic-resolve which provide a solid expression for business descritpions.

diagram = ErDiagram(
    configs=[
        Entity(
            kls=Team,
            relationships=[
                Relationship( field='id', target_kls=list[Sprint], loader=sprint_loader.team_to_sprint_loader),
                Relationship( field='id', target_kls=list[User], loader=user_loader.team_to_user_loader)
            ]
        ),
        Entity(
            kls=Sprint,
            relationships=[
                Relationship( field='id', target_kls=list[Story], loader=story_loader.sprint_to_story_loader)
            ]
        ),
        Entity(
            kls=Story,
            relationships=[
                Relationship( field='id', target_kls=list[Task], loader=task_loader.story_to_task_loader),
                Relationship( field='owner_id', target_kls=User, loader=user_loader.user_batch_loader)
            ]
        ),
        Entity(
            kls=Task,
            relationships=[
                Relationship( field='owner_id', target_kls=User, loader=user_loader.user_batch_loader)
            ]
        )
    ]
)

# display in voyager
app.mount('/voyager', 
          create_voyager(
            app,
            er_diagram=diagram)

Show pydantic resolve meta info

setting enable_pydantic_resolve_meta=True in create_voyager, toggle pydantic resolve meta.

Command Line Usage

open in browser

# open in browser
voyager -m tests.demo --server  

voyager -m tests.demo --server --port=8002

generate the dot file

# generate .dot file
voyager -m tests.demo  

voyager -m tests.demo --app my_app

voyager -m tests.demo --schema Task

voyager -m tests.demo --show_fields all

voyager -m tests.demo --module_color=tests.demo:red --module_color=tests.service:tomato

voyager -m tests.demo -o my_visualization.dot

voyager --version

voyager --help

About pydantic-resolve

pydantic-resolve is a lightweight tool designed to build complex, nested data in a simple, declarative way. In v2 it introduced an important feature: ER Diagram, and fastapi-voyager has supported this feature, allowing for a clearer understanding of the business relationships.

pydantic-resolve's @ensure_subset decorator DefineSubset metaclass helps safely pick fields from the 'source class' while indicating the reference from the current class to the base class.

Developers can use fastapi-voyager without needing to know anything about pydantic-resolve, but I still highly recommend everyone to give it a try.

Dependencies

• FastAPI
• pydantic-resolve
• Quasar

Credits

• https://apis.guru/graphql-voyager/, thanks for inspiration.
• https://github.com/tintinweb/vscode-interactive-graphviz, thanks for web visualization.

How to develop & contribute?

fork, clone.

install uv.

uv venv
source .venv/bin/activate
uv pip install ".[dev]"
uvicorn tests.programatic:app  --reload

Setup Git Hooks (Optional)

Enable automatic code formatting before commits:

./setup-hooks.sh
# or manually:
git config core.hooksPath .githooks

This will run Prettier automatically before each commit. See .githooks/README.md for details.

open localhost:8000/voyager

frontend:

• src/fastapi_voyager/web/vue-main.js: main js

backend:

• voyager.py: main entry
• render.py: generate dot file
• server.py: serve mode