无法从forms.py导入NamerForm至controllers.py，出现ImportError

问题详情 #

无法从forms.py向controllers.py导入NamerForm，报错信息：

ImportError: cannot import 'NamerForm' from 'application.forms'

移除controllers.py中的name函数后，应用可正常运行。

文件目录结构 #

.venv
|____applications
   |-__init__.py
   |-config.py
   |-controllers.py
   |-forms.py
|____templates
   |-name.html
|____static
|____main.py

相关代码 #

main.py #

from flask import Flask
import os, application.config
from application.config import LocalDevelopmentConfig
from application.database import db


app = None

def create_app():
     app = Flask(__name__, template_folder='templates', static_folder='static')
     app.config['SECRET_KEY']='somekey'
     if os.getenv('ENV',"development") == "production":
          raise Exception("Currently no production config is set up.")
     else:
          print("Starting Local Development")
          app.config.from_object(LocalDevelopmentConfig)
     db.init_app(app)
     app.app_context().push()

     return(app)

app = create_app()


from application.controllers import *
if __name__ == '__main__':
     app.run(host='127.0.0.1', port=8080)

forms.py #

from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired

class NamerForm(FlaskForm):
     name = StringField("write something", validators=[DataRequired()])
     submit = SubmitField("Submit")

controllers.py #

from flask import Flask,render_template, url_for
from flask import current_app as app
#from app import app
from .forms import NamerForm

#---other app routes--------

@app.route("/name", methods = ['GET', 'POST'])
def name():
     name = None
     form = NamerForm()
     if form.validate_on_submit():
         name = form.name.data
         form.name.data = ''
     return(render_template("name.html", name = name, form = form))

解决方案 #

核心问题：包名拼写不一致 #

你的文件目录里是applications（复数，末尾带s），但代码里所有导入都用的是application（单数，不带s），这直接导致Python找不到对应模块，引发导入错误。

修复步骤 #

1. 统一包名拼写
   两种选择二选一：

   • 若保留文件夹名applications，将所有代码中的application替换为applications：
     • main.py中修改导入语句：

       import os, applications.config
       from applications.config import LocalDevelopmentConfig
       from applications.database import db
       # ...
       from applications.controllers import *
       

     • controllers.py中可使用绝对导入：

       from applications.forms import NamerForm
       

   • 若希望代码中用application，将文件夹applications重命名为application。

2. 确认__init__.py存在
   确保包文件夹下有__init__.py文件（空文件即可），Python才能识别它为合法包。

3. 验证依赖安装
   确保已安装flask-wtf，执行命令：

   pip install flask-wtf
   

验证修复 #

修改完成后重启应用，访问/name路径，表单应能正常加载，不再出现导入错误。

内容的提问来源于stack exchange，提问作者HS077