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Create food objects

Pybites

Level: Intermediate (score: 3)

Now with the Pydantic Food model defined we can start creating objects through FastAPI. Exciting!

In this Bite you will make a create_food() endpoint that receives a Food object payload and adds the food to a dictionary. We use an in memory data structure to keep things simple for starters. The endpoint should also return a status_code of 201 upon successful creation.

The foods dictionary will hold the food ids integers as keys and the Food objects as values.

After creation of a food object, foods will effectively hold the following (taken from the tests):

(Pdb) foods
{1: Food(id=1, name='egg', serving_size='piece', kcal_per_serving=78, protein_grams=6.3, fibre_grams=0)}

Note that we realize working with a global object is not ideal, but we wanted to separate FastAPI from SQLModel to teach this in a gradual manner.

Also this just teaches the happy path. In a later Bite we have you add some exception handling in case the object already exists or could not be created.

So go ahead and write this endpoint and look at the tests to see how we validate the code. Have fun!

FastAPI

Code
Tests

import pytest
from fastapi.testclient import TestClient

from app import Food, app, foods

@pytest.fixture
def client():
    client = TestClient(app)
    return client

@pytest.fixture
def food():
    food = Food(
        id=1,
        name="egg",
        serving_size="piece",
        kcal_per_serving=78,
        protein_grams=6.3,
        fibre_grams=1,
    )
    return food

@pytest.fixture
def food_payload():
    return dict(
        id=1,
        name="egg",
        serving_size="piece",
        kcal_per_serving=78,
        protein_grams=6.3,
        fibre_grams=1,
    )

@pytest.fixture
def second_food_payload():
    return dict(
        id=2,
        name="oatmeal",
        serving_size="100 grams",
        kcal_per_serving=336,
        protein_grams=13.2,
        fibre_grams=10.1,
    )

def test_can_only_post(client):
    resp = client.get("/")
    assert resp.status_code == 405

def test_create_food(client, food_payload, food):
    resp = client.post("/", json=food_payload)
    assert resp.status_code == 201
    assert resp.json() == dict(food)
    assert foods == {1: food}

def test_create_two_foods(client, food_payload, second_food_payload):
    for pl in (food_payload, second_food_payload):
        resp = client.post("/", json=pl)
        assert resp.status_code == 201
    assert len(foods) == 2
    names = [food.name for food in foods.values()]
    assert names == ["egg", "oatmeal"]
    total_calories = sum(food.kcal_per_serving for food in foods.values())
    assert total_calories == 414

def test_create_food_default_fibre(client, food_payload):
    del food_payload["fibre_grams"]
    resp = client.post("/", json=food_payload)
    assert resp.status_code == 201
    assert foods[1].fibre_grams == 0

def test_create_food_wrong_food_payload(client, food_payload):
    del food_payload["kcal_per_serving"]
    resp = client.post("/", json=food_payload)
    assert resp.status_code == 422
    details = resp.json()["detail"][0]
    assert details["msg"] == 'Field required'
    assert details["type"] == 'missing'