使用Postgres和SQLAlchemy过滤数组列

Posted 2021-04-25

我有一个带有int []列的简单表，我希望能够选择其中任何一个数组元素与我拥有的值匹配的行，并且我无法在不使用SQLAlchemy的情况下弄清楚如何使用SQLAlchemy原始查询，我不想这样做。

这是表的模式（“testuser”）：

 Column  |          Type          |
---------+------------------------+
 id      | integer                |
 name    | character varying(250) |
 numbers | integer[]              |

以下是样本数据的样子：

 id |  name   |    numbers
----+---------+---------------
  1 | David   | {25,33,42,55}
  2 | Salazar | {11,33,7,19}
  3 | Belinda | {32,6,20,23}
  4 | Casey   | {19,20,27,8}
  5 | Kathie  | {25,31,10,40}
  6 | Dianne  | {25,20,40,39}
  7 | Cortez  | {1,20,18,38}

这是一个生成我想要的SQL语句;我想在Python中完成这一切，而不是简单地编写原始查询（25仅用作示例）。

scrape=# select * from testuser where 25 = ANY(numbers);
 id |  name  |    numbers
----+--------+---------------
  5 | Kathie | {25,31,10,40}
  6 | Dianne | {25,20,40,39}
  1 | David  | {25,33,42,55}
(3 rows)

我发现写另一种方式：

scrape=# select * from testuser where numbers @> ARRAY[25];
 id |  name  |    numbers
----+--------+---------------
  5 | Kathie | {25,31,10,40}
  6 | Dianne | {25,20,40,39}
  1 | David  | {25,33,42,55}
(3 rows)

这是我用来生成表的Python代码：

from sqlalchemy import Column, Integer, String
from sqlalchemy.dialects import postgresql
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

Base = declarative_base()

class TestUser(Base):
    __tablename__ = 'testuser'
    id = Column(Integer, primary_key=True)
    name = Column(String(250))
    numbers = Column(postgresql.ARRAY(Integer))

engine = create_engine('postgresql://postgres:{pw}@localhost:5432/scrape'.format(pw=POSTGRES_PASSWORD))

Base.metadata.create_all(engine)

DBSession = sessionmaker(bind=engine)
session = DBSession()

testcases = [{"numbers": [25, 33, 42, 55], "name": "David"}, {"numbers": [11, 33, 7, 19 ], "name":     "Salazar"}, {"numbers": [32, 6, 20, 23 ], "name": "Belinda"}, {"numbers": [19, 20, 27, 8 ], "name": "Casey"},     {"numbers": [25, 31, 10, 40 ], "name": "Kathie"}, {"numbers": [25, 20, 40, 39 ], "name": "Dianne"},     {"numbers": [1, 20, 18, 38 ], "name": "Cortez"} ]

for t in testcases:
    session.add(TestUser(name=t['name'], numbers=t['numbers']))
session.commit()

答案

所以你想使用Postgres Array Comparator。

query = session.query(TestUser).filter(TestUser.numbers.contains([some_int])).all()

要么

query = session.query(TestUser).filter(TestUser.numbers.any(25)).all()

另一答案

该死的SQLAlchemy，花了我一些时间才弄清楚正确的方法是：

TelegramUser.query.filter(TelegramUser.selected_exchanges.contains(f"{{{platform_name}}}")).all()

platform_name是str，selected_exchanges列的定义如下：

from sqlalchemy.dialects import postgresql as pg

selected_exchanges = db.Column(pg.ARRAY(db.String, dimensions=1), nullable=True)