Question

尝试在烧瓶中使用简单的rest api和基本的东西。当我尝试介绍数据库时，导入模型失败了

app.py

from flask import Flask, jsonify, request 
from flask_sqlalchemy import SQLAlchemy 
from flask_migrate import Migrate

import redis from rq import Queue

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db' 
db = SQLAlchemy(app) 
migrate = Migrate(app, db)

from models import OcrText

models.py

from app import db

class OcrText(db.Model):
    # schema

错误

Traceback (most recent call last): 
File "app.py", line 21, in <module> from models import OcrText
File "/Users/mid_dev/Learn/Flask/mercari_ml_ocr/models.py", line 1, in <module> from app import db
File "/Users/mid_dev/Learn/Flask/mercari_ml_ocr/app.py", line 21, in <module> from models import OcrText
ImportError: cannot import name 'OcrText'

Answer 1

是的，您是正确的，这是一个循环导入问题。只需将数据库初始化移至新文件db.py，然后从app.py和models.py导入此文件。这样就可以正常工作。

示例db.py

from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate

db = None


def init_db(app):
    global db

    db = SQLAlchemy(app)
    Migrate(app, db)

    return db

示例app.py

from db import init_db

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
init_db(app)

from models import OcrText

示例models.py

from db import db

class OcrText(db.Model):
    # schema

Flask应用程序中可能存在循环导入问题

1 个答案: