Quickstart

A simple CRUD API can be written as given below, noting that the database url should be customised to match your setup (the given URL creates an in memory sqlite database).

schema.py

from quart import g, Quart, request
from quart_db import QuartDB

app = Quart(__name__)
db = QuartDB(app, url="sqlite:memory:")

@app.get("/")
async def get_all():
    results = await g.connection.fetch_all("SELECT col1, col2 FROM tbl")
    return [{"a": row["col1"], "b": row["col2"]} for row in results]

@app.post("/")
async def create():
    data = await request.get_json()
    await g.connection.execute(
        "INSERT INTO tbl (col1, col2) VALUES (:col1, :col2)",
        {"col1": data["a"], "col2": data["b"]},
    )
    return {}

@app.get("/<int:id>")
async def get(id):
    result = await g.connection.fetch_one(
        "SELECT col1, col2 FROM tbl WHERE id = :id",
        {"id": id},
    )
    return {"a": result["col1"], "b": result["col2"]}

@app.delete("/<int:id>")
async def delete(id):
    await g.connection.execute("DELETE FROM tbl WHERE id = :id", {"id": id})
    return {}

@app.put("/<int:id>")
async def update(id):
    data = await request.get_json()
    await g.connection.execute(
        "UPDATE tbl SET col1 = :col1, col2 = :col2 WHERE id = :id",
        {"id": id, "col1": data["a"], "col2": data["b"]},
    )
    return {}

Initial migrations

In the above example it is assumed there is a table named tbl with columns id, col1 and col2. If the database does not have a structure (schema) or you wish to change it, a migration can be used.

Quart-DB looks for migrations in a migrations folder that should be placed alongside the application (as with templates). A example would be placing the following in migrations/0.py

migrations/0.py

async def migrate(connection):
    await connection.execute(
        "CREATE TABLE tbl (id INT NOT NULL PRIMARY KEY, col1 TEXT, col2 TEXT)"
    )

async def valid_migration(connection):
    return True

This migration will run once when the application starts. See Migrations for more.