更新SQLAlchemy中的PostgreSQL数组字段
考虑以下可标记模型:更新SQLAlchemy中的PostgreSQL数组字段,postgresql,sqlalchemy,Postgresql,Sqlalchemy,考虑以下可标记模型: from sqlalchemy import cast, Text from sqlalchemy.dialects.postgresql import ARRAY, array class User(Base): __tablename__ = 'users' tags = Column(ARRAY(Text), nullable=False, default=cast(array([], type_=Text),
from sqlalchemy import cast, Text
from sqlalchemy.dialects.postgresql import ARRAY, array
class User(Base):
__tablename__ = 'users'
tags = Column(ARRAY(Text), nullable=False,
default=cast(array([], type_=Text), ARRAY(Text)))
我似乎找不到任何关于如何更新该字段的文档。当然,我可以按照以下建议做一些事情:
但该解决方案假定设置整个数组值
如果我只想在数组中附加一个值呢?如果我想在一个查询中批量标记一组User
对象,该怎么办?如何做到这一点?您可以使用SQLAlchemy和PostgreSQL函数:
text('array\u append(tags,:tag)
对于smallint
类型,您可以使用PostgreSQL和:
text('array\u append(tags,:tag\:\:smallint)
TestTable.tags.contains(cast((1,),TestTable.tags.type))
示例:
将值追加到整数PostgreSQL数组:
from sqlalchemy.orm import sessionmaker, scoped_session
from sqlalchemy import create_engine, Column, Integer, update, text
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class TestTable(Base):
__tablename__ = 'test_table'
id = Column(Integer, primary_key=True)
tags = Column(ARRAY(Integer), nullable=False)
engine = create_engine('postgresql://postgres')
Base.metadata.create_all(bind=engine)
DBSession = scoped_session(sessionmaker())
DBSession.configure(bind=engine)
DBSession.bulk_insert_mappings(
TestTable,
({'id': i, 'tags': [i // 4]} for i in range(1, 11))
)
DBSession.execute(
update(
TestTable
).where(
TestTable.tags.contains((1,))
).values(tags=text(f'array_append({TestTable.tags.name}, :tag)')),
{'tag': 100}
)
DBSession.commit()
from sqlalchemy import SmallInteger, cast
class TestTable(Base):
__tablename__ = 'test_table2'
id = Column(Integer, primary_key=True)
tags = Column(ARRAY(SmallInteger), nullable=False)
DBSession.execute(
update(
TestTable
).where(
TestTable.tags.contains(cast((1,), TestTable.tags.type))
).values(tags=text(f'array_append({TestTable.tags.name}, :tag\:\:smallint)')),
{'tag': 100}
)
将值追加到小整数PostgreSQL数组:
from sqlalchemy.orm import sessionmaker, scoped_session
from sqlalchemy import create_engine, Column, Integer, update, text
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class TestTable(Base):
__tablename__ = 'test_table'
id = Column(Integer, primary_key=True)
tags = Column(ARRAY(Integer), nullable=False)
engine = create_engine('postgresql://postgres')
Base.metadata.create_all(bind=engine)
DBSession = scoped_session(sessionmaker())
DBSession.configure(bind=engine)
DBSession.bulk_insert_mappings(
TestTable,
({'id': i, 'tags': [i // 4]} for i in range(1, 11))
)
DBSession.execute(
update(
TestTable
).where(
TestTable.tags.contains((1,))
).values(tags=text(f'array_append({TestTable.tags.name}, :tag)')),
{'tag': 100}
)
DBSession.commit()
from sqlalchemy import SmallInteger, cast
class TestTable(Base):
__tablename__ = 'test_table2'
id = Column(Integer, primary_key=True)
tags = Column(ARRAY(SmallInteger), nullable=False)
DBSession.execute(
update(
TestTable
).where(
TestTable.tags.contains(cast((1,), TestTable.tags.type))
).values(tags=text(f'array_append({TestTable.tags.name}, :tag\:\:smallint)')),
{'tag': 100}
)
结果:
id | tags
----+---------
1 | {0}
2 | {0}
3 | {0}
8 | {2}
9 | {2}
10 | {2}
4 | {1,100}
5 | {1,100}
6 | {1,100}
7 | {1,100}
对于前者。请注意,session.add(user)
是多余的<代码>用户在获取后已处于会话
中,并且不是暂时的。