ormar/docs/fastapi/index.md

Fastapi

The use of ormar with fastapi is quite simple.

Apart from connecting to databases at startup everything else you need to do is substitute pydantic models with ormar models.

Here you can find a very simple sample application code.

!!!warning This example assumes that you already have a database created. If that is not the case please visit database initialization section.

!!!tip The following example (all sections) should be put in one file.

It's divided into subsections for clarity.

!!!note If you want to read more on how you can use ormar models in fastapi requests and responses check the responses and requests documentation.

Quick Start

!!!note Note that you can find the full quick start script in the github repo under examples.

Imports and initialization

Define startup and shutdown procedures using FastAPI lifespan and use is in the application.

from typing import List, Optional

import databases
import sqlalchemy
from fastapi import FastAPI

import ormar

from contextlib import asynccontextmanager
from fastapi import FastAPI


@asynccontextmanager
async def lifespan(_: FastAPI) -> AsyncIterator[None]:
    if not config.database.is_connected:
        await config.database.connect()

    yield

    if config.database.is_connected:
        await config.database.disconnect()


base_ormar_config = ormar.OrmarConfig(
    metadata=sqlalchemy.MetaData(),
    database=databases.Database("sqlite:///test.db"),
)
app = FastAPI(lifespan=lifespan(base_ormar_config))

!!!info You can read more on connecting to databases in fastapi documentation

Models definition

Define ormar models with appropriate fields.

Those models will be used instead of pydantic ones.

base_ormar_config = OrmarConfig(
    metadata = metadata
    database = database
)


class Category(ormar.Model):
    ormar_config = base_ormar_config.copy(tablename="categories")

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)


class Item(ormar.Model):
    ormar_config = base_ormar_config.copy()

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    category: Optional[Category] = ormar.ForeignKey(Category, nullable=True)

!!!tip You can read more on defining Models in models section.

Fastapi endpoints definition

Define your desired endpoints, note how ormar models are used both as response_model and as a requests parameters.

@app.get("/items/", response_model=List[Item])
async def get_items():
    items = await Item.objects.select_related("category").all()
    return items


@app.post("/items/", response_model=Item)
async def create_item(item: Item):
    await item.save()
    return item


@app.post("/categories/", response_model=Category)
async def create_category(category: Category):
    await category.save()
    return category


@app.put("/items/{item_id}")
async def get_item(item_id: int, item: Item):
    item_db = await Item.objects.get(pk=item_id)
    return await item_db.update(**item.model_dump())


@app.delete("/items/{item_id}")
async def delete_item(item_id: int, item: Item = None):
    if item:
        return {"deleted_rows": await item.delete()}
    item_db = await Item.objects.get(pk=item_id)
    return {"deleted_rows": await item_db.delete()}

!!!note Note how ormar Model methods like save() are available straight out of the box after fastapi initializes it for you.

!!!note Note that you can return a Model (or list of Models) directly - fastapi will jsonize it for you

Test the application

Run fastapi

If you want to run this script and play with fastapi swagger install uvicorn first

pip install uvicorn

And launch the fastapi.

uvicorn <filename_without_extension>:app --reload

Now you can navigate to your browser (by default fastapi address is 127.0.0.1:8000/docs) and play with the api.

!!!info You can read more about running fastapi in fastapi docs.

Test with pytest

Here you have a sample test that will prove that everything works as intended.

Be sure to create the tables first. If you are using pytest you can use a fixture.

@pytest.fixture(autouse=True, scope="module")
def create_test_database():
    engine = sqlalchemy.create_engine(DATABASE_URL)
    metadata.create_all(engine)
    yield
    metadata.drop_all(engine)

# here is a sample test to check the working of the ormar with fastapi

from starlette.testclient import TestClient

def test_all_endpoints():
    # note that TestClient is only sync, don't use asyns here
    client = TestClient(app)
    # note that you need to connect to database manually
    # or use client as contextmanager during tests
    with client as client:
        response = client.post("/categories/", json={"name": "test cat"})
        category = response.json()
        response = client.post(
            "/items/", json={"name": "test", "id": 1, "category": category}
        )
        item = Item(**response.json())
        assert item.pk is not None

        response = client.get("/items/")
        items = [Item(**item) for item in response.json()]
        assert items[0] == item

        item.name = "New name"
        response = client.put(f"/items/{item.pk}", json=item.model_dump())
        assert response.json() == item.model_dump()

        response = client.get("/items/")
        items = [Item(**item) for item in response.json()]
        assert items[0].name == "New name"

        response = client.delete(f"/items/{item.pk}", json=item.model_dump())
        assert response.json().get("deleted_rows", "__UNDEFINED__") != "__UNDEFINED__"
        response = client.get("/items/")
        items = response.json()
        assert len(items) == 0

!!!tip If you want to see more test cases and how to test ormar/fastapi see tests directory in the github repo

!!!info You can read more on testing fastapi in fastapi docs.