如何迁移更改以升级mysql数据库

Question

我正在开发一个分类广告网站，使用 Flask 和 mysql 作为数据库。我对数据库模型做了一些更改。例如，我在 ForSaleAd 中添加了价格、品牌、型号。我尝试将更改升级到mysql数据库。我在 init.py 中运行 db.init_app 后添加迁移设置。但是，数据库中没有任何变化。 这是项目结构：

classified_ads
|
|___app
|    |
|    |_static
|    |
|    |_templates 
|    |
|    |__init.py__
|    |
|    |__category.py
|    |
|    |__model.py
|
|___myenv
|
|___config.py
|
|___main.py

init.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager
from config import Config
from flask_migrate import Migrate

db = SQLAlchemy()
login_manager = LoginManager()
login_manager.login_view = 'auth.login'
def create_app():
    app = Flask(__name__)
    #load configuration files
    app.config.from_object(Config)    
    db.init_app(app)

    #migrate changes to database
    migrate = Migrate(app, db)
    migrate.init_app(app, db)

    from .model import User,init_categories
    with app.app_context():
        db.create_all()
        init_categories()        
    
    login_manager.init_app(app)
    @login_manager.user_loader
    def load_user(user_id):
        return User.get(user_id)
    
    return app

model.py
from app import db
from flask_login import UserMixin
from werkzeug.security import generate_password_hash,check_password_hash

#represents a registered user
class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)    
    email = db.Column(db.String(120), unique=True, nullable=False)
    password_hash = db.Column(db.String(128))
    ...

#ad's main category
class Category(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True, nullable=False)
    subcategories = db.relationship('Subcategory')

#ad's subcategory
class Subcategory(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), unique=True, nullable=False)
    category_id = db.Column(db.Integer, db.ForeignKey('category.id'), nullable=False)

#base ad with common fields provide template
class Ad(db.Model):
    __abstract__ = True
    id = db.Column(db.Integer, primary_key=True)
    subject = db.Column(db.String, nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
    subcategory_id = db.Column(db.Integer, db.ForeignKey('subcategory.id'), nullable=False)
    ...

class HousingAd(Ad):
    __tablename__ = 'housing_ad'
    rent = db.Column(db.Float)
    rent_period = db.Column(db.Enum('day', 'week', 'month'))    
    type = db.Column(db.Enum('room', 'house', 'homestay', 'vacation', 'other'))

class ForSaleAd(Ad):
    __tablename__ = 'for_sale_ad'
    price = db.Column(db.Float)
    brand = db.Column(db.String)
    make = db.Column(db.String)
    model = db.Column(db.String)
    condition = db.Column(db.Enum('new','used','deficiency'))

class JobAd(Ad):
    __tablename__ = 'job_ad'
    industry = db.Column(db.String)
    compensation = db.Column(db.String)

class Payment(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    card_number = db.Column(db.String(16), nullable=False)
    ...
#create category and subcategory names
from . import category
def init_categories():
    for cat_name, subcats in category.categories.items():
        categry = Category.query.filter_by(name=cat_name).first()
        if not categry:
            categry = Category(name=cat_name)
            db.session.add(categry)
            db.session.commit()

        for subcat_name in subcats:
            subcat = Subcategory.query.filter_by(name=subcat_name, category_id=categry.id).first()
            if not subcat:
                subcat = Subcategory(name=subcat_name, category_id=categry.id)
                db.session.add(subcat)

    db.session.commit()


category.py
categories = {
    "Housing": [
        "Housing available",
        "Housing wanted",
        "Other"
        ],
    "For Sale": [
        "Appliance",
        "Auto",
        "Clothes", 
        "Computer",
        "Phone",
        "Electronics", 
        "Free",  
        "Household", 
        "Transportation", 
        "Musical Instrument", 
        "Wanted", 
        "Other"
        ],
    "Jobs": [
        "Admin Office", 
        "Customer Service",
        "Driver",
        "Food Restaurant",
        "General Labor",
        "Job Seeking",
        "Landscaping",
        "Massage",
        "Nanny",
        "Warehouse",
        "Software IT",
        "Other"
        ]
}

config.py
class Config:
    SECRET_KEY = 'dev'
    SQLALCHEMY_DATABASE_URI ='mysql+pymysql://root:psword@localhost/databasename'

main.py
from flask import render_template,url_for
from app import create_app
from app import category

app = create_app()
bunch of routes...

Answer 1

我找到了解决办法。我之前更改了文件夹名称，这就是代码不起作用的原因。因此，我更新 Flask 配置文件中的文件夹名称以识别新路径。然后我使用

flask db init; flask db migrate -m 'initial changes'; flask db upgrade;

来升级数据库。