postgresql - 一对多，Flask-SqlAlchemy，sqlalchemy.exc.ProgrammingError : (psycopg2. ProgrammingError)关系不存在

Question

我在尝试测试是否可以将一些记录保存到数据库中时遇到了问题。我使用 postgres.app 作为数据库。在尝试测试之前，我做了:

dropdb testdb
createdb testdb
python db_create.py

我的 models.py 看起来像这样:

class Municipality(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    municipality_name = db.Column(db.String(120), unique=True)
    population = db.Column(db.Integer)
    region_id = db.Column(db.Integer, db.ForeignKey('region.id'))

    def __init__(self, municipality_name, population, region_id):
        self.municipality_name = municipality_name
        self.population = population
        self.region_id = region_id

    def __repr__(self):
        return '{0}'.format(self.municipality_name)

class Region(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    region_name = db.Column(db.String(120), unique=True)
    region_capital = db.Column(db.String(120), unique=True)
    population = db.Column(db.Integer)
    municipalities = db.relationship('Municipality', backref=db.backref('region'))

    def __init__(self, region_name, region_capital, population):
        self.region_name = region_name
        self.region_capital = region_capital
        self.population = population

    def __repr__(self):
        return '{0}'.format(self.region_name)

我试试

todb = Region(region_name='Ahvenanmaa',region_capital='Maarianhamina',population=123)
db.session.add(todb)
db.session.commit()

在这一步我得到了一个错误:

sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) relation "region" does not exist
LINE 1: INSERT INTO region (region_name, region_capital, population)...
                    ^
 [SQL: 'INSERT INTO region (region_name, region_capital, population) VALUES (%(region_name)s, %(region_capital)s, %(population)s) RETURNING region.id'] [parameters: {'population': 123, 'region_capital': 'Maarianhamina', 'region_name': 'Ahvenanmaa'}]

我想我遗漏了在 python db_create.py 之后我必须做的一些步骤。你能建议一些方法来解决这个问题吗？

Answer 1

看起来您还没有完成(第一次)迁移。我相信您需要 $ ./db_migrate.py