Connection¶
Connection is a class that represents a connection to a database. Connections are used to communicate with databases.
Creating a Connection¶
To create a connection, create a root function with the class Connection as an argument.
from pykour import Pykour, Config
from pykour.db import Connection
app = Pykour(config=Config("config.yml"))
@app.get("/")
def index(conn: Connection):
return conn.fetch_one("SELECT * FROM users")
The above example creates an index function with the Connection class as an argument.
This function uses the Connection class to retrieve user information from the database.
Connection Methods¶
The Connection class provides a low-level API.
fetch_one method¶
The fetch_one method executes the specified SQL query and returns the first row of results.
result = conn.fetch_one("SELECT * FROM users")
fetch_all method¶
The fetch_all method executes the given SQL query and returns all rows of the result.
results = conn.fetch_all("SELECT * FROM users")
execute method¶
The execute method executes the specified SQL query. The execute method returns the number of rows executed.
ret = conn.execute("INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com')")
commit method¶
The commit method commits a transaction.
conn.commit()
rollback method¶
The rollback method rolls back a transaction.
conn.rollback()
close method¶
The close method closes a connection.
conn.close()
Parameterized Queries¶
Parameterization, rather than embedding variables directly in SQL, allows for separation of query and parameters.
result = conn.fetch_one("SELECT * FROM users WHERE id = ?", 1)
The above example uses the ? placeholder to specify the parameter.
The second argument to the fetch_one method is the parameter value.