# Step 1: Setup your Puff project
Follow the instructions on how to setup a new poetry project and install Puff:
* [Using the CLI](https://github.com/hansonkd/puff/blob/master/book/CLI.md)
# Step 2: Add a FastAPI app
Install FastAPI to your your project:
```
poetry add fastapi
```
Add your flask application in a new file `my_puff_project/fastapi.py`
```python
from fastapi import FastAPI
app = FastAPI()
@app.get("/fast-api")
async def read_root():
return "<p>Hello, World!</p>"
```
Update `puff.toml` with the following lines
```toml
asyncio = true
asgi = "my_puff_project.fastapi.app"
```
Run the server:
```bash
poetry run puff serve
```
To use Puff in development mode, use `puff-watch` which is a wrapper around puff that will restart the process when files change in the directory.
```bash
poetry run puff-watch serve
# Spawn multiple processes on the same Port to simulate hypercorn workers
PUFF_REUSE_PORT=true poetry run puff-watch --num 2 serve
```
# Step 3: Add GraphQL
Create a new file called `my_puff_project/graphql.py`
```python
from typing import Optional, Iterable, Tuple, List, Any
from dataclasses import dataclass
from puff.pubsub import global_pubsub as pubsub
@dataclass
class DbObject:
was_input: int
title: str
@dataclass
class Query:
@classmethod
def hello_world(cls, parents, context, /, my_input: int) -> Tuple[List[DbObject], str, List[Any]]:
# Return a Raw query for Puff to execute in Postgres.
# The ellipsis is a placeholder allowing the Python type system to know which field type it should transform into.
return ..., "SELECT $1::int as was_input, \'hi from pg\'::TEXT as title", [my_input]
@classmethod
def auth_token(cls, context, /) -> str:
# All GraphQL queries have access to the Bearer token if set.
return context.auth_token()
@classmethod
def new_connection_id(cls, context, /) -> str:
# Get a new connection identifier for pubsub.
return pubsub.new_connection_id()
@dataclass
class Mutation:
@classmethod
def send_message_to_channel(cls, context, /, connection_id: str, channel: str, message: str) -> bool:
return pubsub.publish_as(connection_id, channel, message)
@dataclass
class MessageObject:
message_text: str
from_connection_id: str
num_processed: int
@dataclass
class Subscription:
@classmethod
def read_messages_from_channel(cls, context, /, channel: str, connection_id: Optional[str] = None) -> Iterable[MessageObject]:
if connection_id is not None:
conn = pubsub.connection_with_id(connection_id)
else:
conn = pubsub.connection()
conn.subscribe(channel)
num_processed = 0
while msg := conn.receive():
from_connection_id = msg.from_connection_id
# Filter out messages from yourself.
if connection_id != from_connection_id:
yield MessageObject(message_text=msg.text, from_connection_id=from_connection_id, num_processed=num_processed)
num_processed += 1
@dataclass
class Schema:
query: Query
mutation: Mutation
subscription: Subscription
```
Update `puff.toml` with the following lines
```toml
pubsub = true
postgres = true
graphql_schema = "my_puff_project.graphql.Schema"
graphql_url = "/graphql/"
graphql_subscription_url = "/subscriptions/"
graphql_playground_url = "/playground/"
```
Run the server and go to `http://localhost:7777/playground/`
# Step 4: Add Distributed Tasks
Update `puff.toml` with the following lines
```toml
task_queue = true
```
Create a new file called `my_puff_project/tasks.py`
```python
def my_task(payload):
print(f"Inside `my_task` with payload: {payload}")
return {"from_task": payload}
```
Change your `Mutation` class in `graphql.py` to call the function through the queue:
```python
from puff.task_queue import global_task_queue as tq
from my_puff_project.tasks import my_task
...
@dataclass
class Mutation:
@classmethod
def send_message_to_channel(cls, context, /, connection_id: str, channel: str, message: str) -> bool:
tq.add_task(my_task, {"auth_token": context.auth_token(), "connection_id": connection_id, "channel": channel, "message": message})
return pubsub.publish_as(connection_id, channel, message)
```
Run a worker server by using wait_forever in another tab:
```bash
poetry run puff wait_forever
```
Now run the server. Going to `http://localhost:7777/graphql/` calling the mutation will trigger tasks.
```bash
poetry run puff serve
```