如何强制 Flask/SQLAlchemy 创建表？

Question

我第一次将 Flask 与 flask.ext.sqlalchemy 一起使用。我收到一个错误，告诉我一个表不存在，但我认为对象关系设置会解决这个问题。可能不会。我在以下代码中缺少什么？

from flask import Flask, request, url_for
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.secret_key = 'This is really unique and secret'

db = SQLAlchemy(app)
app.config['SQLALCHEMY_DATABASE_URI'] ='mysql://golfape:mypass@mysql.server/golfape$swarm'


class Suggestion(db.Model):
    __tablename__ = 'suggestions'
    id   = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.String(100))

    def __init__( self, name ):
        self.name = name

@app.route('/')
def get_suggestion():
    return """
        <p>What do you think swarm prediction could be applied to?</p>
        <form method = "POST" action="%s">
             <input name="name" />
             <input type="submit" value="Go!" />
         </form>
         """ % (url_for('append_suggestion'),)


@app.route('/suggestions', methods=['POST'] )
def append_suggestion():
    name = request.form["name"]
    newSuggestion = Suggestion( name = name )
    db.session.add( newSuggestion )
    db.session.commit()
    return """
        <p>Thanks for suggesting %s</p>
        <p><a href="%s">Back</a></p>
        """ % (name, url_for('get_suggestion'))

这是错误：

默认错误处理程序中的文件“/usr/local/lib/python2.7/dist-packages/MySQLdb/connections.py”，第 36 行 引发错误类，错误值 ProgrammingError: (ProgrammingError) (1146, "Table 'golfape$swarm.suggestions' 不存在") 'INSERT INTOSuggestions (name) VALUES (%s)' ('fishing',)

Answer 1

您必须调用一次 db.create_all() 才能让 sqlalchemy 创建架构：

from my_app import Suggestion, db
db.create_all()

此外，您必须在初始化 db 之前移动数据库配置 URL 行：

app.config['SQLALCHEMY_DATABASE_URI'] ='mysql://golfape:mypass@mysql.server/golfape$swarm'
db = SQLAlchemy(app)

更新 上面提到的问题是关于连接到 mysql db 并为它找到合适的连接器。安装以下模块：

pip install pymysql

并像这样更改您的连接字符串：

db = SQLAlchemy('mysql+pymysql://user:password@mysql.server/database_name')