Question

这个周末，我一直在为Python使用sqlite3 stdlib模块。我对SQL完全陌生。

我试图编写一个测试外键的测试，但是不幸的是segments表似乎没有被填充，即fetchall()不返回任何结果。我看了看db文件，每个表的声明都存在，但是似乎只填充了points。谁能提供一些见识？

import json
import attr
import random
import pytest
import datetime as dt
import typing as typ
import sqlite3 as sql


@attr.s
class Point:
    x: float = attr.ib(default=random.random())
    y: float = attr.ib(default=random.random())


def adapt_point(point: Point) -> str:
    data = attr.asdict(point)
    text = json.dumps(data)
    return text


def convert_point(value: bytes) -> Point:
    data = json.loads(value)
    value = Point(**data)
    return value


sql.register_adapter(Point, adapt_point)
sql.register_converter('point', convert_point)


@pytest.fixture
def connection():
    con = sql.connect('tmpdb.sqlite', detect_types=sql.PARSE_DECLTYPES)
    cur = con.cursor()
    cur.execute(
        """
        create table points(
            id integer primary key,
            pt point,
            at timestamp
        );  
        """
    )
    cur.execute(
        """
        create table segments(
            id integer primary key,
            start integer,
            end integer,
            at timestamp,
            foreign key(start) references points(id),
            foreign key(end) references points(id)
        ); 
        """
    )
    con.commit()
    yield con
    con.close()


def test_insert_points(connection: sql.Connection):
    """
    Test adding:

    * datetime object using builtin 'timestamp' adapter and converter
    * dataclass object using custom adapter and converter using :py:func:`attr.asdict`

    :param connection: sqlite fixture
    """
    cur = connection.cursor()

    for i in range(5):
        cur.execute(
            "insert into points(id, pt, at) values (?, ?, ?)",
            (i, Point(), dt.datetime.now())
        )

    connection.commit()


def test_insert_segments(connection: sql.Connection):
    """
    Test adding:

    * datetime object using builtin 'timestamp' adapter and converter
    * foreign keys to other table

    :param connection: sqlite fixture
    """
    cur = connection.cursor()

    for i in range(3):
        cur.execute(
            "insert into segments(id, start, end, at) values (?, ?, ?, ?)",
            (i, random.randrange(5), random.randrange(5), dt.datetime.now())
        )

    connection.commit()


def test_retrieve_points_from_segment(connection: sql.Connection):
    cur = connection.cursor()
    cur.row_factory = sql.Row

    cur.execute("select * from segments")

    segs = cur.fetchall()
    assert segs is not None, "THIS FAILS"

未填充外键的表

0 个答案: