15

我正在尝试使用 SQLAlchemy Core 中的 SQL 语句更新 PostgreSQL 表上的整数数组。我第一次尝试使用查询生成器，但也不知道该怎么做。我相信我使用的方言 Psycopg2 可以自动将数组形成 PostgreSQL 可以接受的格式。

这是表架构：

CREATE TABLE surveys (
    survey_id serial PRIMARY KEY,
    question_ids_ordered INTEGER[],
    created_at TIMESTAMP NOT NULL DEFAULT now(),
);

和 SQLAlchemy 语句：

survey_id = 46
question_ids_ordered = [237, 238, 239, 240, 241, 242, 243]

with engine.begin() as conn:
    conn.execute("""UPDATE surveys
                    SET question_ids_ordered = %s
                    WHERE survey_id = %s""",
                    question_ids_ordered, survey_id)

我收到的回溯是：

Traceback (most recent call last):
  File "foo.py", line 16, in <module>
    res = add_question_to_group(current_user, 46, 358, question_ids_ordered, new_group_name="Jellyfish?")
  File "/vagrant/workspace/panel/panel/survey.py", line 80, in add_question_to_group
    question_ids_ordered, survey_id)
  File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/base.py", line 664, in execute
    params)
  File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/base.py", line 808, in _execute_text
    statement, parameters
  File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/base.py", line 831, in _execute_context
    None, None)
  File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/base.py", line 827, in _execute_context
    context = constructor(dialect, self, conn, *args)
  File "/home/vagrant/.virtualenvs/project/lib/python2.6/site-packages/sqlalchemy/engine/default.py", line 513, in _init_statement
    for p in parameters]
sqlalchemy.exc.StatementError: 'int' object is not iterable (original cause: TypeError: 'int' object is not iterable) 'UPDATE surveys\n                        SET question_ids_ordered = %s\n                        WHERE survey_id = %s' ([237, 238, 239, 240, 241, 242, 243], 46)

我究竟做错了什么？

4

2 回答 2

19

如果你的表是这样定义的：

from datetime import datetime
from sqlalchemy import *
from sqlalchemy.dialects.postgresql import ARRAY

meta = MetaData()
surveys_table = Table('surveys', meta,
    Column('surveys_id', Integer, primary_key=True),
    Column('questions_ids_ordered', ARRAY(Integer)),
    Column('created_at', DateTime, nullable=False, default=datetime.utcnow)
)

然后您可以通过以下方式简单地更新您的数组（与 psycopg2 一起使用）：

engine = create_engine('postgresql://localhost')
conn = engine.connect()
u = surveys_table.update().where(surveys_table.c.id == 46).\
     values(questions_ids_ordered=[237, 238, 239, 240, 241, 242, 243])
conn.execute(u)
conn.close()

或者，如果您愿意，可以使用text()构造编写原始 SQL：

from sqlalchemy.sql import text
with engine.connect() as conn:
    u = text('UPDATE surveys SET questions_ids_ordered = :q WHERE id = :id')
    conn.execute(u, q=[237, 238, 239, 240, 241, 242, 243], id=46)
于 2013-01-08T18:33:19.197 回答
1

在 Flask 中，您的调查表的模型将如下所示：

class Survey(UserMixin, db.Model):
    __tablename__ = 'surveys'
    id = db.Column(db.Integer, primary_key=True)
    question_ids_ordered = db.Column('question_ids_ordered', db.ARRAY(db.Integer))

并且您想更新question_ids_ordered字段，您可以像这样使用 ORM：

from sqlalchemy.orm.attributes import flag_modified

survery = (Survey
           .query
           .filter(Survey.id == 46)).first()

survery.question_ids_ordered.remove(237)
flag_modified(survery, "question_ids_ordered")
db.session.merge(survery)
db.session.flush()
db.session.commit()
于 2021-12-01T21:12:13.780 回答