AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
This skill provides a systematic approach to instrumenting FastAPI applications with PostHog. It covers the full lifecycle of integration, from initial setup and configuration to advanced implementation patterns like user identification, custom event tracking, feature flags, and error reporting. The skill emphasizes best practices such as using environment variables for sensitive keys, leveraging FastAPI's dependency injection, and maintaining a clean separation between event properties and user identification data to ensure privacy.
What it does
- Provides a step-by-step workflow for PostHog integration.
- Demonstrates how to initialize PostHog within FastAPI's lifespan context manager.
- Shows how to implement user identification and property tracking.
- Explains how to capture custom events and manage feature flags.
- Guides the implementation of manual exception tracking for critical API operations.
- Enforces security best practices regarding PII and environment variable usage.
When to use it
- When you need to add analytics to a new or existing FastAPI project.
- When you want to track user behavior, conversion funnels, or churn.
- When you need to implement feature flags to control application functionality.
- When you need to improve observability through automated and manual error tracking.
Advantages
- Follows established patterns for FastAPI dependency injection and configuration.
- Ensures consistent event tracking across server-side business logic.
- Promotes secure handling of sensitive data and API keys.
- Includes clear examples for complex tasks like user correlation between frontend and backend.
Usage examples
- “How do I initialize PostHog in my FastAPI app?”
- The skill guides you to use the lifespan context manager, configuring the Posthog() constructor with your project token and host, and ensuring proper shutdown with atexit.
- “How should I track user signups in FastAPI?”
- The skill demonstrates using the context-based API to identify the user via email and capture the 'user_signed_up' event with relevant properties.
- “How do I track errors in my API routes?”
- The skill provides a pattern for wrapping critical operations in a try-except block and using posthog.capture_exception(e) to report failures.
Install
Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/posthog/integration-fastapi/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip integration-fastapi.zip -d .agents/skills
Documentation by PostHog
PostHog integration for FastAPI
This skill helps you add PostHog analytics to FastAPI applications.
Workflow
Follow these steps in order to complete the integration:
basic-integration-1.0-begin.md- PostHog Setup - Begin ← Start herebasic-integration-1.1-edit.md- PostHog Setup - Editbasic-integration-1.2-revise.md- PostHog Setup - Revisebasic-integration-1.3-conclude.md- PostHog Setup - Conclusion
Reference files
references/EXAMPLE.md- FastAPI example project codereferences/python.md- Python - docsreferences/identify-users.md- Identify users - docsreferences/basic-integration-1.0-begin.md- PostHog setup - beginreferences/basic-integration-1.1-edit.md- PostHog setup - editreferences/basic-integration-1.2-revise.md- PostHog setup - revisereferences/basic-integration-1.3-conclude.md- PostHog setup - conclusion
The example project shows the target implementation pattern. Consult the documentation for API details.
Key principles
Environment variables: Always use environment variables for PostHog keys. Never hardcode them.
Minimal changes: Add PostHog code alongside existing integrations. Don't replace or restructure existing code.
Match the example: Your implementation should follow the example project's patterns as closely as possible.
Framework guidelines
Initialize PostHog in the lifespan context manager on startup using posthog.api_key and posthog.host
Call posthog.flush() in the lifespan shutdown to ensure all events are sent before the app exits
Use Pydantic Settings with @lru_cache decorator on get_settings() for caching and easy test overrides
Use FastAPI dependency injection (Depends) for accessing current_user and settings in route handlers
Use the same context API pattern as Flask/Django (with new_context(), identify_context(user_id), then capture())
Remember that source code is available in the venv/site-packages directory
posthog is the Python SDK package name
Install dependencies with
pip install posthogorpip install -r requirements.txtand do NOT use unquoted version specifiers like>=directly in shell commandsIn CLIs and scripts: MUST call posthog.shutdown() before exit or all events are lost
Always use the Posthog() class constructor (instance-based API) instead of module-level posthog.api_key config
Always include enable_exception_autocapture=True in the Posthog() constructor to automatically track exceptions
NEVER send PII in capture() event properties — no emails, full names, phone numbers, physical addresses, IP addresses, or user-generated content
PII belongs in identify() person properties, NOT in capture() event properties. Safe event properties are metadata like message_length, form_type, boolean flags.
Register posthog_client.shutdown with atexit.register() to ensure all events are flushed on exit
The Python SDK has NO identify() method — use posthog_client.set(distinct_id=user_id, properties={...}) to set person properties, or use identify_context(user_id) within a context
Identifying users
Identify users during login and signup events. Refer to the example code and documentation for the correct identify pattern for this framework. If both frontend and backend code exist, pass the client-side session and distinct ID using X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID headers to maintain correlation.
Error tracking
Add PostHog error tracking to relevant files, particularly around critical user flows and API boundaries.
Files
- ATTRIBUTION.mdAdded by AutoGineer957 B
- LICENSELicence file added by AutoGineer1.0 KiB
- SKILL.md3.6 KiB
- references/EXAMPLE.md40.9 KiB
- references/basic-integration-1.0-begin.md2.1 KiB
- references/basic-integration-1.1-edit.md2.5 KiB
- references/basic-integration-1.2-revise.md937 B
- references/basic-integration-1.3-conclude.md1.6 KiB
- references/identify-users.md8.1 KiB
- references/python.md31.1 KiB
references/EXAMPLE.md
PostHog FastAPI Example Project
Repository: https://github.com/PostHog/context-mill Path: basics/fastapi
README.md
PostHog FastAPI Example
A FastAPI application demonstrating PostHog integration for analytics, feature flags, and error tracking.
Features
User registration and authentication with cookie-based sessions
SQLite database persistence with SQLAlchemy
User identification and property tracking
Custom event tracking
Feature flags with payload support
Error tracking with manual exception capture
Quick Start
Create and activate a virtual environment:
python -m venv venv source venv/bin/activate # On Windows: venv\Scripts\activateInstall dependencies:
pip install -r requirements.txtCopy the environment file and configure:
cp .env.example .env # Edit .env with your PostHog project keyRun the application:
python run.pyOpen http://localhost:5002 and either:
Login with default credentials:
[email protected]/adminOr click "Sign up here" to create a new account
PostHog Integration Points
User Registration
New users are identified and tracked on signup using the context-based API:
with new_context():
identify_context(user.email)
tag('email', user.email)
tag('is_staff', user.is_staff)
capture('user_signed_up', properties={'signup_method': 'form'})User Identification
Users are identified on login with their properties:
with new_context():
identify_context(user.email)
tag('email', user.email)
tag('is_staff', user.is_staff)
capture('user_logged_in', properties={'login_method': 'password'})Event Tracking
Custom events are captured throughout the app:
with new_context():
identify_context(current_user.email)
capture('burrito_considered', properties={'total_considerations': count})Feature Flags
The dashboard demonstrates feature flag checking:
show_new_feature = posthog.feature_enabled(
'new-dashboard-feature',
current_user.email,
person_properties={'email': current_user.email, 'is_staff': current_user.is_staff}
)
feature_config = posthog.get_feature_flag_payload('new-dashboard-feature', current_user.email)Error Tracking
The example demonstrates two approaches to error tracking:
Manual capture for specific critical operations** (app/routers/api.py).
try:
# Critical operation that might fail
result = process_payment()
except Exception as e:
# Manually capture this specific exception
with new_context():
identify_context(current_user.email)
event_id = posthog.capture_exception(e)
return JSONResponse({
"error": "Operation failed",
"error_id": event_id,
"message": f"Error captured in PostHog. Reference ID: {event_id}"
}, status_code=500)The /api/test-error endpoint demonstrates manual exception capture. Use ?capture=true to capture in PostHog, or ?capture=false to skip tracking.
Project Structure
basics/fastapi/
├── app/
│ ├── __init__.py # Package marker
│ ├── config.py # Pydantic Settings configuration
│ ├── database.py # SQLAlchemy setup
│ ├── dependencies.py # FastAPI dependency injection
│ ├── main.py # Application factory and lifespan
│ ├── models.py # User model (SQLAlchemy)
│ ├── routers/
│ │ ├── __init__.py # Routers package
│ │ ├── main.py # Page routes (HTML)
│ │ └── api.py # API endpoints (JSON)
│ └── templates/ # Jinja2 templates
├── .env.example
├── .gitignore
├── requirements.txt
├── README.md
└── run.py # Entry point (uvicorn).env.example
POSTHOG_PROJECT_TOKEN=<ph_project_token>
POSTHOG_HOST=https://us.i.posthog.com
SECRET_KEY=your-secret-key-here
DEBUG=True
POSTHOG_DISABLED=False
app/init.py
"""FastAPI PostHog example application."""
app/config.py
"""FastAPI application configuration using Pydantic Settings."""
from functools import lru_cache
from pydantic_settings import BaseSettings, SettingsConfigDict
class Settings(BaseSettings):
"""Application settings loaded from environment variables."""
model_config = SettingsConfigDict(
env_file=".env",
env_file_encoding="utf-8",
extra="ignore",
)
# Application
secret_key: str = "dev-secret-key-change-in-production"
debug: bool = True
# Database (SQLite like Flask example)
database_url: str = "sqlite:///./db.sqlite3"
# PostHog
posthog_project_token: str = "<ph_project_token>"
posthog_host: str = "https://us.i.posthog.com"
posthog_disabled: bool = False
@lru_cache
def get_settings() -> Settings:
"""Get cached settings instance."""
return Settings()
app/database.py
"""Database configuration with SQLAlchemy."""
from sqlalchemy import create_engine
from sqlalchemy.orm import DeclarativeBase, sessionmaker
from app.config import get_settings
settings = get_settings()
engine = create_engine(
settings.database_url,
connect_args={"check_same_thread": False}, # Required for SQLite
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
class Base(DeclarativeBase):
"""Base class for SQLAlchemy models."""
pass
def get_db():
"""Dependency that provides a database session."""
db = SessionLocal()
try:
yield db
finally:
db.close()
def init_db():
"""Create all database tables."""
Base.metadata.create_all(bind=engine)
app/dependencies.py
"""Authentication dependencies for FastAPI."""
from typing import Annotated, Optional
from fastapi import Cookie, Depends, HTTPException, status
from itsdangerous import BadSignature, URLSafeSerializer
from sqlalchemy.orm import Session
from app.config import get_settings
from app.database import get_db
from app.models import User
settings = get_settings()
serializer = URLSafeSerializer(settings.secret_key)
def get_session_user_id(session_token: Annotated[Optional[str], Cookie()] = None) -> Optional[int]:
"""Extract user ID from session cookie."""
if not session_token:
return None
try:
data = serializer.loads(session_token)
return data.get("user_id")
except BadSignature:
return None
def get_current_user(
db: Annotated[Session, Depends(get_db)],
user_id: Annotated[Optional[int], Depends(get_session_user_id)],
) -> Optional[User]:
"""Get the current authenticated user, or None if not authenticated."""
if user_id is None:
return None
return User.get_by_id(db, user_id)
def require_auth(
current_user: Annotated[Optional[User], Depends(get_current_user)],
) -> User:
"""Require authentication - raises 401 if not authenticated."""
if current_user is None:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Authentication required",
)
return current_user
def create_session_token(user_id: int) -> str:
"""Create a signed session token for the user."""
return serializer.dumps({"user_id": user_id})
# Type aliases for cleaner dependency injection
CurrentUser = Annotated[Optional[User], Depends(get_current_user)]
RequiredUser = Annotated[User, Depends(require_auth)]
DbSession = Annotated[Session, Depends(get_db)]
app/main.py
"""FastAPI application with PostHog integration."""
from contextlib import asynccontextmanager
from pathlib import Path
import posthog
from fastapi import FastAPI, Request
from fastapi.responses import HTMLResponse, JSONResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates
from app.config import get_settings
from app.database import SessionLocal, init_db
from app.middleware import PostHogMiddleware
from app.models import User
from app.routers import api, main
settings = get_settings()
# Setup templates
templates_dir = Path(__file__).parent / "templates"
templates = Jinja2Templates(directory=str(templates_dir))
@asynccontextmanager
async def lifespan(app: FastAPI):
"""Application lifespan events for startup/shutdown."""
# Startup: Initialize PostHog
if not settings.posthog_disabled:
posthog.api_key = settings.posthog_project_token
posthog.host = settings.posthog_host
posthog.debug = settings.debug
# Initialize database and seed default user
init_db()
db = SessionLocal()
try:
if not User.get_by_email(db, "[email protected]"):
User.create_user(
db,
email="[email protected]",
password="admin",
is_staff=True,
)
finally:
db.close()
yield
# Shutdown: Flush PostHog events
if not settings.posthog_disabled:
posthog.flush()
app = FastAPI(
title="PostHog FastAPI Example",
description="Example application demonstrating PostHog integration with FastAPI",
lifespan=lifespan,
)
app.add_middleware(PostHogMiddleware)
# Include routers
app.include_router(main.router)
app.include_router(api.router, prefix="/api")
# Error handlers
@app.exception_handler(404)
async def not_found_handler(request: Request, exc):
"""Handle 404 errors."""
if request.url.path.startswith("/api/"):
return JSONResponse({"error": "Not found"}, status_code=404)
return templates.TemplateResponse(
request, "errors/404.html", status_code=404
)
@app.exception_handler(500)
async def internal_error_handler(request: Request, exc):
"""Handle 500 errors."""
if request.url.path.startswith("/api/"):
return JSONResponse({"error": "Internal server error"}, status_code=500)
return templates.TemplateResponse(
request, "errors/500.html", status_code=500
)
app/middleware.py
"""PostHog middleware for automatic context and user identification.
Uses pure ASGI middleware instead of BaseHTTPMiddleware for better performance/best practices.
"""
from http.cookies import SimpleCookie
from typing import Callable, Optional
from posthog import identify_context, new_context, tag
from app.config import get_settings
from app.database import SessionLocal
from app.dependencies import serializer
from app.models import User
class PostHogMiddleware:
"""Pure ASGI middleware that wraps each request in a PostHog context.
If the user is authenticated, identifies them in the context so routes
can just call capture() without needing to set up context each time.
Uses pure ASGI interface for better performance than BaseHTTPMiddleware.
"""
def __init__(self, app):
self.app = app
self.settings = get_settings()
async def __call__(self, scope, receive, send):
if scope["type"] != "http" or self.settings.posthog_disabled:
await self.app(scope, receive, send)
return
user = self._get_user_from_scope(scope)
with new_context():
if user:
identify_context(user.email)
tag("email", user.email)
tag("is_staff", user.is_staff)
await self.app(scope, receive, send)
def _get_user_from_scope(self, scope) -> Optional[User]:
"""Extract authenticated user from session cookie in ASGI scope."""
headers = dict(scope.get("headers", []))
cookie_header = headers.get(b"cookie", b"").decode("utf-8")
if not cookie_header:
return None
cookies = SimpleCookie()
cookies.load(cookie_header)
session_cookie = cookies.get("session_token")
if not session_cookie:
return None
session_token = session_cookie.value
try:
data = serializer.loads(session_token)
user_id = data.get("user_id")
except Exception:
return None
if not user_id:
return None
db = SessionLocal()
try:
return User.get_by_id(db, user_id)
finally:
db.close()
app/models.py
"""User model with SQLite persistence (similar to Flask example)."""
from datetime import datetime, timezone
from typing import Optional
from sqlalchemy import Boolean, DateTime, Integer, String
from sqlalchemy.orm import Mapped, Session, mapped_column
from werkzeug.security import check_password_hash, generate_password_hash
from app.database import Base
class User(Base):
"""User model with SQLite persistence."""
__tablename__ = "users"
id: Mapped[int] = mapped_column(Integer, primary_key=True)
email: Mapped[str] = mapped_column(String(254), unique=True, nullable=False)
password_hash: Mapped[str] = mapped_column(String(256), nullable=False)
name: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
is_staff: Mapped[bool] = mapped_column(Boolean, default=False)
is_active: Mapped[bool] = mapped_column(Boolean, default=True)
login_count: Mapped[int] = mapped_column(Integer, default=0)
date_joined: Mapped[datetime] = mapped_column(
DateTime, default=lambda: datetime.now(timezone.utc)
)
def set_password(self, password: str) -> None:
"""Hash and set the user's password."""
self.password_hash = generate_password_hash(password, method="pbkdf2:sha256")
def check_password(self, password: str) -> bool:
"""Verify the password against the hash."""
return check_password_hash(self.password_hash, password)
@classmethod
def create_user(
cls, db: Session, email: str, password: str, is_staff: bool = False
) -> "User":
"""Create and save a new user."""
user = cls(email=email, is_staff=is_staff)
# nosemgrep: python.django.security.audit.unvalidated-password.unvalidated-password
user.set_password(password)
db.add(user)
db.commit()
db.refresh(user)
return user
@classmethod
def get_by_id(cls, db: Session, user_id: int) -> Optional["User"]:
"""Get user by ID."""
return db.query(cls).filter(cls.id == user_id).first()
@classmethod
def get_by_email(cls, db: Session, email: str) -> Optional["User"]:
"""Get user by email."""
return db.query(cls).filter(cls.email == email).first()
@classmethod
def authenticate(cls, db: Session, email: str, password: str) -> Optional["User"]:
"""Authenticate user with email and password."""
user = cls.get_by_email(db, email)
if user and user.check_password(password):
return user
return None
def record_login(self, db: Session) -> bool:
"""Record a login and return whether this is the user's first login."""
is_first_login = self.login_count == 0
self.login_count += 1
db.commit()
return is_first_login
def update_profile(self, db: Session, name: Optional[str] = None) -> list:
"""Update user profile and return list of changed fields."""
changed_fields = []
if name is not None and name != self.name:
self.name = name
changed_fields.append("name")
if changed_fields:
db.commit()
return changed_fields
def __repr__(self) -> str:
return f"<User {self.email}>"
app/routers/init.py
"""FastAPI routers package."""
app/routers/api.py
"""API endpoints demonstrating PostHog integration patterns."""
from typing import Annotated
import posthog
from fastapi import APIRouter, Cookie, Form, Query
from fastapi.responses import JSONResponse
from posthog import capture
from app.dependencies import RequiredUser
router = APIRouter()
MAX_BURRITO_COUNT = 10000
@router.post("/burrito/consider")
async def consider_burrito(
current_user: RequiredUser,
burrito_count: Annotated[int, Cookie()] = 0,
):
"""Track burrito consideration event."""
safe_count = max(0, min(burrito_count, MAX_BURRITO_COUNT))
new_count = safe_count + 1
capture("burrito_considered", properties={"total_considerations": new_count})
response = JSONResponse({"success": True, "count": new_count})
response.set_cookie(
key="burrito_count",
value=str(new_count),
httponly=True,
samesite="lax",
)
return response
@router.post("/test-error")
async def test_error(
current_user: RequiredUser,
capture_param: Annotated[str, Query(alias="capture")] = "true",
):
"""Test endpoint demonstrating manual exception capture in PostHog."""
should_capture = capture_param.lower() == "true"
try:
raise Exception("Test exception from critical operation")
except Exception as e:
if should_capture:
event_id = posthog.capture_exception(e)
return JSONResponse(
{
"error": "Operation failed",
"error_id": event_id,
"message": f"Error captured in PostHog. Reference ID: {event_id}",
},
status_code=500,
)
else:
return JSONResponse({"error": "Operation failed"}, status_code=500)
@router.post("/trigger-error")
async def trigger_error(
current_user: RequiredUser,
error_type: Annotated[str, Form()] = "generic",
):
"""Trigger different error types for testing error tracking."""
error_messages = {
"value": "Invalid value provided",
"key": "Missing required key",
"generic": "Generic test error",
}
safe_error_type = error_type if error_type in error_messages else "generic"
error_message = error_messages[safe_error_type]
try:
if safe_error_type == "value":
raise ValueError(error_message)
elif safe_error_type == "key":
raise KeyError("missing_key")
else:
raise Exception(error_message)
except Exception as e:
posthog.capture_exception(e)
capture(
"error_triggered",
properties={"error_type": safe_error_type, "error_message": error_message},
)
return JSONResponse(
{
"success": True,
"message": "Error captured in PostHog",
"error": error_message,
}
)
@router.post("/reports/activity")
async def generate_activity_report(
current_user: RequiredUser,
report_type: Annotated[str, Form()] = "summary",
):
"""Generate user activity report."""
valid_report_types = {"summary", "detailed", "export"}
safe_report_type = report_type if report_type in valid_report_types else "summary"
report_data = {
"user": current_user.email,
"name": current_user.name,
"date_joined": current_user.date_joined.isoformat(),
"login_count": current_user.login_count,
"is_staff": current_user.is_staff,
}
if safe_report_type == "detailed":
report_data["account_age_days"] = (
__import__("datetime").datetime.now(__import__("datetime").timezone.utc)
- current_user.date_joined
).days
row_count = len(report_data)
capture(
"report_generated",
properties={
"report_type": safe_report_type,
"row_count": row_count,
"username": current_user.email,
},
)
return JSONResponse(
{
"success": True,
"report_type": safe_report_type,
"row_count": row_count,
"data": report_data,
}
)
app/routers/main.py
"""Main routes demonstrating PostHog integration patterns."""
from pathlib import Path
from typing import Annotated
import posthog
from fastapi import APIRouter, Cookie, Depends, Form, Request
from fastapi.responses import HTMLResponse, RedirectResponse
from fastapi.templating import Jinja2Templates
from posthog import capture
from app.dependencies import (
CurrentUser,
DbSession,
RequiredUser,
create_session_token,
)
from app.models import User
router = APIRouter()
# Setup templates
templates_dir = Path(__file__).parent.parent / "templates"
templates = Jinja2Templates(directory=str(templates_dir))
@router.get("/", response_class=HTMLResponse)
async def home(request: Request, current_user: CurrentUser, db: DbSession):
"""Home/login page."""
if current_user:
return RedirectResponse(url="/dashboard", status_code=302)
return templates.TemplateResponse(
request, "home.html", {"current_user": current_user}
)
@router.post("/", response_class=HTMLResponse)
async def login(
request: Request,
db: DbSession,
email: Annotated[str, Form()],
password: Annotated[str, Form()],
):
"""Handle login form submission."""
user = User.authenticate(db, email, password)
if user:
is_new_user = user.record_login(db)
posthog.identify(user.email, {"email": user.email, "is_staff": user.is_staff})
posthog.capture(
user.email,
"user_logged_in",
properties={
"username": user.email,
"is_new_user": is_new_user,
},
)
# Create session and redirect
response = RedirectResponse(url="/dashboard", status_code=302)
response.set_cookie(
key="session_token",
value=create_session_token(user.id),
httponly=True,
samesite="lax",
)
return response
# Login failed
return templates.TemplateResponse(
request,
"home.html",
{"current_user": None, "error": "Invalid email or password"},
)
@router.get("/signup", response_class=HTMLResponse)
async def signup_page(request: Request, current_user: CurrentUser):
"""User registration page."""
if current_user:
return RedirectResponse(url="/dashboard", status_code=302)
return templates.TemplateResponse(
request, "signup.html", {"current_user": current_user}
)
@router.post("/signup", response_class=HTMLResponse)
async def signup(
request: Request,
db: DbSession,
email: Annotated[str, Form()],
password: Annotated[str, Form()],
password_confirm: Annotated[str, Form()],
):
"""Handle signup form submission."""
error = None
if not email or not password:
error = "Email and password are required"
elif password != password_confirm:
error = "Passwords do not match"
elif User.get_by_email(db, email):
error = "Email already registered"
if error:
return templates.TemplateResponse(
request, "signup.html", {"current_user": None, "error": error}
)
# Create new user
user = User.create_user(db, email=email, password=password, is_staff=False)
posthog.identify(user.email, {"email": user.email, "is_staff": user.is_staff})
posthog.capture(
user.email,
"user_signed_up",
properties={
"username": user.email,
"signup_method": "form",
},
)
# Create session and redirect
response = RedirectResponse(url="/dashboard", status_code=302)
response.set_cookie(
key="session_token",
value=create_session_token(user.id),
httponly=True,
samesite="lax",
)
return response
@router.get("/logout")
async def logout(current_user: RequiredUser):
"""Logout and capture event."""
capture("user_logged_out")
response = RedirectResponse(url="/", status_code=302)
response.delete_cookie(key="session_token")
return response
@router.get("/dashboard", response_class=HTMLResponse)
async def dashboard(
request: Request,
current_user: RequiredUser,
):
"""Dashboard with feature flag demonstration."""
capture("dashboard_viewed", properties={"is_staff": current_user.is_staff})
# Check feature flag
show_new_feature = posthog.feature_enabled(
"new-dashboard-feature",
current_user.email,
person_properties={
"email": current_user.email,
"is_staff": current_user.is_staff,
},
)
# Get feature flag payload
feature_config = posthog.get_feature_flag_payload(
"new-dashboard-feature", current_user.email
)
return templates.TemplateResponse(
request,
"dashboard.html",
{
"current_user": current_user,
"show_new_feature": show_new_feature,
"feature_config": feature_config,
},
)
@router.get("/burrito", response_class=HTMLResponse)
async def burrito(
request: Request,
current_user: RequiredUser,
burrito_count: Annotated[int, Cookie()] = 0,
):
"""Burrito consideration tracker page."""
return templates.TemplateResponse(
request,
"burrito.html",
{"current_user": current_user, "burrito_count": burrito_count},
)
@router.get("/profile", response_class=HTMLResponse)
async def profile(request: Request, current_user: RequiredUser):
"""User profile page."""
capture("profile_viewed")
return templates.TemplateResponse(
request, "profile.html", {"current_user": current_user}
)
@router.post("/profile", response_class=HTMLResponse)
async def update_profile(
request: Request,
db: DbSession,
current_user: RequiredUser,
name: Annotated[str, Form()],
):
"""Handle profile update."""
fields_changed = current_user.update_profile(db, name=name)
if fields_changed:
capture(
"profile_updated",
properties={
"username": current_user.email,
"fields_changed": fields_changed,
},
)
return templates.TemplateResponse(
request,
"profile.html",
{
"current_user": current_user,
"success": "Profile updated" if fields_changed else None,
},
)
app/templates/base.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>{% block title %}PostHog FastAPI Example{% endblock %}</title>
<style>
* {
box-sizing: border-box;
margin: 0;
padding: 0;
}
body {
font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
line-height: 1.6;
background-color: #f5f5f5;
color: #333;
}
.container {
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
nav {
background: #1d4ed8;
padding: 15px 20px;
margin-bottom: 30px;
}
nav a {
color: white;
text-decoration: none;
margin-right: 20px;
}
nav a:hover {
text-decoration: underline;
}
.card {
background: white;
border-radius: 8px;
padding: 20px;
margin-bottom: 20px;
box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
h1, h2, h3 {
margin-bottom: 15px;
color: #1d4ed8;
}
button, .btn {
background: #1d4ed8;
color: white;
border: none;
padding: 10px 20px;
border-radius: 5px;
cursor: pointer;
font-size: 14px;
display: inline-block;
text-decoration: none;
}
button:hover, .btn:hover {
background: #1e40af;
}
button.danger {
background: #dc2626;
}
button.danger:hover {
background: #b91c1c;
}
input {
width: 100%;
padding: 10px;
margin-bottom: 15px;
border: 1px solid #ddd;
border-radius: 5px;
font-size: 14px;
}
.messages {
margin-bottom: 20px;
}
.message {
padding: 10px 15px;
border-radius: 5px;
margin-bottom: 10px;
}
.message.error {
background: #fee2e2;
color: #dc2626;
}
.message.success {
background: #d1fae5;
color: #059669;
}
.feature-flag {
background: #fef3c7;
border: 2px dashed #f59e0b;
padding: 15px;
border-radius: 8px;
margin: 20px 0;
}
code {
background: #f3f4f6;
padding: 2px 6px;
border-radius: 3px;
font-family: monospace;
}
pre {
background: #1e293b;
color: #e2e8f0;
padding: 16px;
border-radius: 8px;
overflow-x: auto;
font-size: 13px;
}
.count {
font-size: 48px;
font-weight: bold;
color: #1d4ed8;
text-align: center;
padding: 20px;
}
table {
width: 100%;
border-collapse: collapse;
margin: 16px 0;
}
th, td {
padding: 12px;
text-align: left;
border-bottom: 1px solid #eee;
}
th {
background: #f8fafc;
font-weight: 600;
}
</style>
</head>
<body>
{% if current_user %}
<nav>
<a href="/dashboard">Dashboard</a>
<a href="/burrito">Burrito</a>
<a href="/profile">Profile</a>
<a href="/logout" style="float: right;">Logout ({{ current_user.email }})</a>
</nav>
{% endif %}
<div class="container">
{% if error %}
<div class="messages">
<div class="message error">{{ error }}</div>
</div>
{% endif %}
{% if success %}
<div class="messages">
<div class="message success">{{ success }}</div>
</div>
{% endif %}
{% block content %}{% endblock %}
</div>
{% block scripts %}{% endblock %}
</body>
</html>
app/templates/burrito.html
{% extends "base.html" %}
{% block title %}Burrito - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>Burrito Consideration Tracker</h1>
<p>This page demonstrates custom event tracking with PostHog.</p>
<div class="count" id="burrito-count">{{ burrito_count }}</div>
<p style="text-align: center; color: #666;">Times you've considered a burrito</p>
<div style="text-align: center; margin-top: 20px;">
<button onclick="considerBurrito()">Consider a Burrito</button>
</div>
</div>
<div class="card">
<h3>Code Example</h3>
<pre>
# API endpoint captures the event
with new_context():
identify_context(current_user.email)
capture('burrito_considered', properties={
'total_considerations': burrito_count
})</pre>
</div>
{% endblock %}
{% block scripts %}
<script>
async function considerBurrito() {
try {
const response = await fetch('/api/burrito/consider', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
}
});
const data = await response.json();
if (data.success) {
document.getElementById('burrito-count').textContent = data.count;
}
} catch (error) {
console.error('Error:', error);
}
}
</script>
{% endblock %}
app/templates/dashboard.html
{% extends "base.html" %}
{% block title %}Dashboard - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>Dashboard</h1>
<p>Welcome back, {{ current_user.email }}!</p>
</div>
<div class="card">
<h2>Feature Flags</h2>
{% if show_new_feature %}
<div class="feature-flag">
<strong>New Feature Enabled!</strong>
<p>You're seeing this because the <code>new-dashboard-feature</code> flag is enabled for you.</p>
{% if feature_config %}
<p><strong>Feature Configuration:</strong></p>
<pre>{{ feature_config | tojson(indent=2) }}</pre>
{% endif %}
</div>
{% else %}
<p>The <code>new-dashboard-feature</code> flag is not enabled for your account.</p>
{% endif %}
<h3 style="margin-top: 20px;">Code Example</h3>
<pre>
# Check if feature flag is enabled
show_new_feature = posthog.feature_enabled(
'new-dashboard-feature',
user_id,
person_properties={
'email': current_user.email,
'is_staff': current_user.is_staff
}
)
# Get feature flag payload
feature_config = posthog.get_feature_flag_payload(
'new-dashboard-feature',
user_id
)</pre>
</div>
{% endblock %}
app/templates/errors/404.html
{% extends "base.html" %}
{% block title %}Page Not Found - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>404 - Page Not Found</h1>
<p>The page you're looking for doesn't exist.</p>
<a href="/" class="btn">Go Home</a>
</div>
{% endblock %}
app/templates/errors/500.html
{% extends "base.html" %}
{% block title %}Server Error - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>500 - Internal Server Error</h1>
<p>Something went wrong on our end. Please try again later.</p>
<a href="/" class="btn">Go Home</a>
</div>
{% endblock %}
app/templates/home.html
{% extends "base.html" %}
{% block title %}Login - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>Welcome to PostHog FastAPI Example</h1>
<p>This example demonstrates how to integrate PostHog with a FastAPI application.</p>
<form method="POST">
<label for="email">Email</label>
<input type="email" id="email" name="email" required>
<label for="password">Password</label>
<input type="password" id="password" name="password" required>
<button type="submit">Login</button>
</form>
<p style="margin-top: 16px; font-size: 14px; color: #666;">
Don't have an account? <a href="/signup">Sign up here</a>
</p>
<p style="font-size: 14px; color: #666;">
<strong>Tip:</strong> Default credentials are [email protected]/admin
</p>
</div>
<div class="card">
<h2>Features Demonstrated</h2>
<ul style="margin-left: 20px; color: #666;">
<li>User registration and identification</li>
<li>Event tracking</li>
<li>Feature flags</li>
<li>Error tracking</li>
<li>Group analytics</li>
</ul>
</div>
{% endblock %}
app/templates/profile.html
{% extends "base.html" %}
{% block title %}Profile - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>Your Profile</h1>
<p>This page demonstrates profile updates and report generation with PostHog.</p>
{% if success %}
<div class="message success">{{ success }}</div>
{% endif %}
<form method="POST" action="/profile">
<table>
<tr>
<th>Email</th>
<td>{{ current_user.email }}</td>
</tr>
<tr>
<th>Name</th>
<td>
<input type="text" name="name" value="{{ current_user.name or '' }}" placeholder="Enter your name">
</td>
</tr>
<tr>
<th>Date Joined</th>
<td>{{ current_user.date_joined.strftime('%Y-%m-%d %H:%M') }}</td>
</tr>
<tr>
<th>Login Count</th>
<td>{{ current_user.login_count }}</td>
</tr>
<tr>
<th>Staff Status</th>
<td>{{ 'Yes' if current_user.is_staff else 'No' }}</td>
</tr>
</table>
<button type="submit">Update Profile</button>
</form>
</div>
<div class="card">
<h2>Activity Reports</h2>
<p>Generate a report of your account activity:</p>
<div style="margin: 20px 0;">
<button onclick="generateReport('summary')">Summary Report</button>
<button onclick="generateReport('detailed')">Detailed Report</button>
</div>
<div id="report-result" style="display: none;" class="message"></div>
</div>
<div class="card">
<h2>Error Tracking Demo</h2>
<p>Click a button to trigger an error and see it captured in PostHog:</p>
<div style="margin: 20px 0;">
<button class="danger" onclick="triggerError('value')">
Trigger ValueError
</button>
<button class="danger" onclick="triggerError('key')">
Trigger KeyError
</button>
<button class="danger" onclick="triggerError('generic')">
Trigger Generic Error
</button>
</div>
<div id="error-result" style="display: none;" class="message"></div>
</div>
<div class="card">
<h3>Code Example</h3>
<pre>
try:
raise ValueError('Invalid value provided')
except Exception as e:
# Capture exception and event with user context
with new_context():
identify_context(current_user.email)
posthog.capture_exception(e)
capture('error_triggered', properties={
'error_type': 'value',
'error_message': str(e)
})</pre>
</div>
{% endblock %}
{% block scripts %}
<script>
async function triggerError(errorType) {
const resultDiv = document.getElementById('error-result');
try {
const formData = new FormData();
formData.append('error_type', errorType);
const response = await fetch('/api/trigger-error', {
method: 'POST',
body: formData
});
const data = await response.json();
resultDiv.style.display = 'block';
resultDiv.className = 'message ' + (data.success ? 'success' : 'error');
resultDiv.textContent = data.message + ': ' + data.error;
} catch (error) {
console.error('Error:', error);
resultDiv.style.display = 'block';
resultDiv.className = 'message error';
resultDiv.textContent = 'Request failed: ' + error.message;
}
}
async function generateReport(reportType) {
const resultDiv = document.getElementById('report-result');
try {
const formData = new FormData();
formData.append('report_type', reportType);
const response = await fetch('/api/reports/activity', {
method: 'POST',
body: formData
});
const data = await response.json();
resultDiv.style.display = 'block';
resultDiv.className = 'message success';
resultDiv.innerHTML = '<strong>' + data.report_type + ' report generated</strong> (' + data.row_count + ' rows)<br><pre>' + JSON.stringify(data.data, null, 2) + '</pre>';
} catch (error) {
console.error('Error:', error);
resultDiv.style.display = 'block';
resultDiv.className = 'message error';
resultDiv.textContent = 'Request failed: ' + error.message;
}
}
</script>
{% endblock %}
app/templates/signup.html
{% extends "base.html" %}
{% block title %}Sign Up - PostHog FastAPI Example{% endblock %}
{% block content %}
<div class="card">
<h1>Create an Account</h1>
<p>Sign up to explore the PostHog FastAPI integration example.</p>
<form method="POST">
<label for="email">Email *</label>
<input type="email" id="email" name="email" required>
<label for="password">Password *</label>
<input type="password" id="password" name="password" required>
<label for="password_confirm">Confirm Password *</label>
<input type="password" id="password_confirm" name="password_confirm" required>
<button type="submit">Sign Up</button>
</form>
<p style="margin-top: 16px; font-size: 14px; color: #666;">
Already have an account? <a href="/">Login here</a>
</p>
</div>
<div class="card">
<h2>PostHog Integration</h2>
<p>When you sign up, the following PostHog events are captured:</p>
<ul style="margin-left: 20px; color: #666;">
<li><code>identify_context()</code> - Associates your email with the context</li>
<li><code>tag()</code> - Sets person properties (email, etc.)</li>
<li><code>user_signed_up</code> event - Tracks the signup action</li>
</ul>
<h3 style="margin-top: 20px;">Code Example</h3>
<pre>
# After creating the user
with new_context():
identify_context(user.email)
tag('email', user.email)
tag('is_staff', user.is_staff)
tag('date_joined', user.date_joined.isoformat())
capture('user_signed_up', properties={'signup_method': 'form'})</pre>
</div>
{% endblock %}
requirements.txt
fastapi>=0.109.0
uvicorn>=0.27.0
sqlalchemy>=2.0.0
python-dotenv>=1.0.0
posthog>=3.0.0
pydantic>=2.0.0
pydantic-settings>=2.0.0
jinja2>=3.0.0
python-multipart>=0.0.9
werkzeug>=3.0.0
itsdangerous>=2.0.0
run.py
"""Development server entry point."""
import uvicorn
if __name__ == "__main__":
uvicorn.run("app.main:app", host="0.0.0.0", port=5002, reload=True)
Requirements and compatibility
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.
Needs: Needs an API key, Needs Python
Security
What our scanner noticed· Low risk
- Instructions that use the network
A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.
Attribution and licence
- Created by
- PostHog
- Publisher
- PostHog (Official)
- Source
- PostHog/skills · skills/posthog/integration/skills/fastapi · commit a5d30e7
- Licence
- MIT License (redistribution allowed)
- LICENSE (added by AutoGineer from LICENSE)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
- Also distributed in
- PostHog/skills
AutoGineer is not affiliated with or endorsed by PostHog.
Download ZIP
The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download integration-fastapi.zip