How to execute raw SQL in SQLAlchemy-flask app
如何在SQLAlchemy中执行原始SQL？
我有一个python web应用程序，运行在flask上，通过sqlachemy接口到数据库。
我需要一种运行原始SQL的方法。查询涉及多个表联接以及内联视图。
我试过了：
1 2 | connection = db.session.connection() connection.execute( <sql here> ) |
但我一直在收到网关错误。
您是否尝试过：
1 | result = db.engine.execute("<sql here>") |
或：
1 2 3 4 5 6 | from sqlalchemy import text sql = text('select name from penguins') result = db.engine.execute(sql) names = [row[0] for row in result] print names |
号
如果您想使用会话(如您的问题所示)，请直接使用其
1 2 3 4 5 6 7 8 | import sqlalchemy from sqlalchemy.orm import sessionmaker, scoped_session engine = sqlalchemy.create_engine('my connection string') Session = scoped_session(sessionmaker(bind=engine)) s = Session() result = s.execute('SELECT * FROM my_table WHERE my_column = :val', {'val': 5}) |
。
以下可能是我的数据库驱动程序(psycopg2)特有的；我不确定。不管怎样，这就是我如何提出自己的价值观。
1 2 3 4 5 6 | from collections import namedtuple Record = namedtuple('Record', result.keys()) records = [Record(*r) for r in result.fetchall()] for r in records: print(r) |
关键是
此外，这是事务性的，不需要手动管理。假设
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | >>> s1 = make_session() >>> s1.execute('CREATE TABLE blah (id INTEGER)') <sqlalchemy.engine.result.ResultProxy object at 0x02CD86F0> >>> s1.commit() >>> >>> s1.execute('INSERT INTO blah VALUES (1)') <sqlalchemy.engine.result.ResultProxy object at 0x02CD8870> >>> s1.execute('SELECT * FROM blah').fetchall() [(1,)] >>> >>> s2 = make_session() >>> s2.execute('SELECT * FROM blah').fetchall() [] >>> s2.close() >>> >>> s1.commit() >>> >>> s2 = make_session() >>> s2.execute('SELECT * FROM blah').fetchall() [(1,)] >>> s2.close() >>> s1.close() |
。
文档：SQL表达式语言教程-使用文本
例子：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | from sqlalchemy.sql import text connection = engine.connect() # recommended cmd = 'select * from Employees where EmployeeGroup == :group' employeeGroup = 'Staff' employees = connection.execute(text(cmd), group = employeeGroup) # or - wee more difficult to interpret the command employeeGroup = 'Staff' employees = connection.execute( text('select * from Employees where EmployeeGroup == :group'), group = employeeGroup) # or - notice the requirement to quote"Staff" employees = connection.execute( text('select * from Employees where EmployeeGroup =="Staff"')) for employee in employees: logger.debug(employee) # output (0, u'Tim', u'Gurra', u'Staff', u'991-509-9284') (1, u'Jim', u'Carey', u'Staff', u'832-252-1910') (2, u'Lee', u'Asher', u'Staff', u'897-747-1564') (3, u'Ben', u'Hayes', u'Staff', u'584-255-2631') |
您可以使用
1 2 3 4 5 6 7 8 9 | from sqlalchemy.sql import text . . . user = session.query(User).from_statement( text("SELECT * FROM users where name=:name")).\ params(name='ed').all() return user |
。
1 | result = db.engine.execute(text("<sql here>")) |
执行
要在更改后提交，请执行
1 | result = db.engine.execute(text("<sql here>").execution_options(autocommit=True)) |
。
This is a simplified answer of how to run SQL query from Flask Shell
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首先，映射您的模块(如果您的模块/应用程序在主文件夹中是manage.py，而您在UNIX操作系统中)，请运行：
1 | export FLASK_APP=manage |
运行烧瓶外壳
1 | flask shell |
。
导入我们需要的内容：
1 2 3 4 | from flask import Flask from flask_sqlalchemy import SQLAlchemy db = SQLAlchemy(app) from sqlalchemy import text |
号
运行查询：
1 | result = db.engine.execute(text("<sql here>").execution_options(autocommit=True)) |
。
这将使用当前具有应用程序的数据库连接。
您是否尝试过使用