✨ Add docs and tests for encode/databases (fastapi#107)

* ✨ Add docs and tests for encode/databases

* ➕ Add testing-only dependency, databases

Pipfile

@@ -27,6 +27,7 @@ uvicorn = "*"
 [packages]
 starlette = "==0.11.1"
 pydantic = "==0.21.0"
+databases = {extras = ["sqlite"],version = "*"}
 
 [requires]
 python_version = "3.6"

docs/src/async_sql_databases/tutorial001.py

@@ -0,0 +1,65 @@
+from typing import List
+
+import databases
+import sqlalchemy
+from fastapi import FastAPI
+from pydantic import BaseModel
+
+# SQLAlchemy specific code, as with any other app
+DATABASE_URL = "sqlite:///./test.db"
+# DATABASE_URL = "postgresql://user:password@postgresserver/db"
+
+database = databases.Database(DATABASE_URL)
+
+metadata = sqlalchemy.MetaData()
+
+notes = sqlalchemy.Table(
+    "notes",
+    metadata,
+    sqlalchemy.Column("id", sqlalchemy.Integer, primary_key=True),
+    sqlalchemy.Column("text", sqlalchemy.String),
+    sqlalchemy.Column("completed", sqlalchemy.Boolean),
+)
+
+
+engine = sqlalchemy.create_engine(
+    DATABASE_URL, connect_args={"check_same_thread": False}
+)
+metadata.create_all(engine)
+
+
+class NoteIn(BaseModel):
+    text: str
+    completed: bool
+
+
+class Note(BaseModel):
+    id: int
+    text: str
+    completed: bool
+
+
+app = FastAPI()
+
+
+@app.on_event("startup")
+async def startup():
+    await database.connect()
+
+
+@app.on_event("shutdown")
+async def shutdown():
+    await database.disconnect()
+
+
+@app.get("/notes/", response_model=List[Note])
+async def read_notes():
+    query = notes.select()
+    return await database.fetch_all(query)
+
+
+@app.post("/notes/", response_model=Note)
+async def create_note(note: NoteIn):
+    query = notes.insert().values(text=note.text, completed=note.completed)
+    last_record_id = await database.execute(query)
+    return {**note.dict(), "id": last_record_id}

docs/tutorial/async-sql-databases.md

@@ -0,0 +1,160 @@
+You can also use <a href="https://github.com/encode/databases" target="_blank">`encode/databases`</a> with **FastAPI** to connect to databases using `async` and `await`.
+
+It is compatible with:
+
+* PostgreSQL
+* MySQL
+* SQLite
+
+In this example, we'll use **SQLite**, because it uses a single file and Python has integrated support. So, you can copy this example and run it as is.
+
+Later, for your production application, you might want to use a database server like **PostgreSQL**.
+
+!!! tip
+    You could adopt ideas from the previous section about <a href="/tutorial/sql-databases/" target="_blank">SQLAlchemy ORM</a>, like using utility functions to perform operations in the database, independent of your **FastAPI** code.
+
+    This section doesn't apply those ideas, to be equivalent to the counterpart in <a href="https://www.starlette.io/database/" target="_blank">Starlette</a>.
+
+## Import and set up `SQLAlchemy`
+
+* Import `SQLAlchemy`.
+* Create a `metadata` object.
+* Create a table `notes` using the `metadata` object.
+
+```Python hl_lines="4 14 16 17 18 19 20 21 22"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+!!! tip
+    Notice that all this code is pure SQLAlchemy Core.
+
+    `databases` is not doing anything here yet.
+
+## Import and set up `databases`
+
+* Import `databases`.
+* Create a `DATABASE_URL`.
+* Create a `database` object.
+
+```Python hl_lines="3 9 12"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+!!! tip
+    If you where connecting to a different database (e.g. PostgreSQL), you would need to change the `DATABASE_URL`.
+
+## Create the tables
+
+In this case, we are creating the tables in the same Python file, but in production, you would probably want to create them with Alembic, integrated with migrations, etc.
+
+Here, this section would run directly, right before starting your **FastAPI** application.
+
+* Create an `engine`.
+* Create all the tables from the `metadata` object.
+
+```Python hl_lines="25 26 27 28"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+## Create models
+
+Create Pydantic models for:
+
+* Notes to be created (`NoteIn`).
+* Notes to be returned (`Note`).
+
+```Python hl_lines="31 32 33 36 37 38 39"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+By creating these Pydantic models, the input data will be validated, serialized (converted), and annotated (documented).
+
+So, you will be able to see it all in the interactive API docs.
+
+## Connect and disconnect
+
+* Create your `FastAPI` application.
+* Create event handlers to connect and disconnect from the database.
+
+```Python hl_lines="42 45 46 47 50 51 52"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+## Read notes
+
+Create the *path operation function* to read notes:
+
+```Python hl_lines="55 56 57 58"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+!!! Note
+    Notice that as we communicate with the database using `await`, the *path operation function* is declared with `async`.
+
+### Notice the `response_model=List[Note]`
+
+It uses `typing.List`.
+
+That documents (and validates, serializes, filters) the output data, as a `list` of `Note`s.
+
+## Create notes
+
+Create the *path operation function* to create notes:
+
+```Python hl_lines="61 62 63 64 65"
+{!./src/async_sql_databases/tutorial001.py!}
+```
+
+!!! Note
+    Notice that as we communicate with the database using `await`, the *path operation function* is declared with `async`.
+
+### About `{**note.dict(), "id": last_record_id}`
+
+`note` is a Pydantic `Note` object.
+
+`note.dict()` returns a `dict` with its data, something like:
+
+```Python
+{
+    "text": "Some note",
+    "completed": False,
+}
+```
+
+but it doesn't have the `id` field.
+
+So we create a new `dict`, that contains the key-value pairs from `note.dict()` with:
+
+```Python
+{**note.dict()}
+```
+
+`**note.dict()` "unpacks" the key value pairs directly, so, `{**note.dict()}` would be, more or less, a copy of `note.dict()`.
+
+And then, we extend that copy `dict`, adding another key-value pair: `"id": last_record_id`:
+
+```Python
+{**note.dict(), "id": last_record_id}
+```
+
+So, the final result returned would be something like:
+
+```Python
+{
+    "id": 1,
+    "text": "Some note",
+    "completed": False,
+}
+```
+
+## Check it
+
+You can copy this code as is, and see the docs at <a href="http://127.0.0.1:8000/docs" target="_blank">http://127.0.0.1:8000/docs</a>.
+
+There you can see all your API documented and interact with it:
+
+<img src="/img/tutorial/async-sql-databases/image01.png">
+
+## More info
+
+You can read more about <a href="https://github.com/encode/databases" target="_blank">`encode/databases` at its GitHub page</a>.