Flask API搭建报错：SQLALCHEMY_DATABASE_URI未定义问题排查与解决

问题场景 #

搭建Flask API基础框架时，配置数据库连接后，IDE及运行程序均提示SQLALCHEMY_DATABASE_URI未定义，但模块导入无异常。

出错代码 #

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlite3 import Connection as SQLite3Connection
from datetime import datetime
from sqlalchemy import event
from sqlalchemy.engine import Engine
from flask import Flask, request, jsonify


app = Flask(__name__)

app.config[SQLALCHEMY_DATABASE_URI] = "sqlite:///sqlitedb.file"
app.config[SQLALCHEMY_TRACK_MODIFICATIONS] = 0

错误原因 #

Flask的app.config是字典类型，配置键需要是字符串。代码中直接使用SQLALCHEMY_DATABASE_URI和SQLALCHEMY_TRACK_MODIFICATIONS作为键，Python会将其识别为未定义的变量，而非字符串键名。

解决方法 #

给配置键添加引号，将其转为字符串类型：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlite3 import Connection as SQLite3Connection
from datetime import datetime
from sqlalchemy import event
from sqlalchemy.engine import Engine
from flask import Flask, request, jsonify


app = Flask(__name__)

# 为配置键添加引号
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///sqlitedb.file"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = 0

内容的提问来源于stack exchange，提问作者dongus