```

To set a value used in the current "context" (e.g. for the current request) use:

```Python
some_var.set("new value")
```

To get a value anywhere inside of the context (e.g. in any part handling the current request) use:

```Python
some_var.get()
```

### Set context variables in the `async` dependency `reset_db_state()`

شما پایتون استاندارد را با استفاده از تایپ ها مینویسید:

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```

که سپس میتوان به این شکل از آن استفاده کرد:

# Templates

You can use any template engine you want with **FastAPI**.

A common choice is Jinja2, the same one used by Flask and other tools.

There are utilities to configure it easily that you can use directly in your **FastAPI** application (provided by Starlette).

## Install dependencies

Install `jinja2`:

<div class="termy">

```console
$ pip install jinja2

---> 100%
```

</div>

"_Python ile kullanıma hazır bir API oluşturmak isteyen herhangi biri için, **FastAPI**'ı şiddetle tavsiye ederim. **Harika tasarlanmış**, **kullanımı kolay** ve **yüksek ölçeklenebilir**, API odaklı geliştirme stratejimizin **ana bileşeni** haline geldi ve Virtual TAC Engineer gibi birçok otomasyon ve servisi yönetiyor._"

The first step is to create a SQLAlchemy "engine".

We will later use this `engine` in other places.

```Python hl_lines="8-10"
{!../../../docs_src/sql_databases/sql_app/database.py!}
```

#### Note

The argument:

```Python
connect_args={"check_same_thread": False}
```

...is needed only for `SQLite`. It's not needed for other databases.

!!! info "Technical Details"

from fastapi.testclient import TestClient
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.pool import StaticPool

from ..database import Base
from ..main import app, get_db

SQLALCHEMY_DATABASE_URL = "sqlite://"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL,
    connect_args={"check_same_thread": False},
    poolclass=StaticPool,
)

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = "sqlite:///./sql_app.db"
# SQLALCHEMY_DATABASE_URL = "postgresql://user:password@postgresserver/db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

If you used to rely on this behavior, now you should create the resources for background tasks inside the background task itself, and use internally only data that doesn't depend on the resources of dependencies with `yield`.

from fastapi import Depends, FastAPI, HTTPException
from sqlalchemy.orm import Session

from . import crud, models, schemas
from .database import SessionLocal, engine

models.Base.metadata.create_all(bind=engine)

app = FastAPI()


# Dependency
def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


@app.post("/users/", response_model=schemas.User)

href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#responseObject" class="external-link" target="_blank">OpenAPI Response Object</a>, you can include anything from this directly in each response inside your `responses` parameter. Including `description`, `headers`, `content` (inside of this is that you declare different media types and JSON Schemas), and `links`....