Python 没有名为'；后端'；

您好，我正在尝试将代码分离到文件中。当我尝试从另一个文件导入任何变量时，出现以下错误：

文件“\app.py”，第2行，在 从后端.Measure导入度量，MeasurementSchema，Measure\u模式，measures\u模式 ModuleNotFoundError:没有名为“backend”的模块

我有3个文件：

• app.py

  from flask import Flask, Request, jsonify
  from backend.Measure import Measure,MeasurementSchema,measure_schema,measures_schema
  from flask_sqlalchemy import SQLAlchemy
  
  app = Flask(__name__)
  
  db = SQLAlchemy(app)
  
  
  @app.route('/api/measures')
  def getAllMeasurements():
      results = Measure.query.all()
      return measures_schema.jsonify(results)
  

• Measure.py

  from flask_marshmallow import Marshmallow
  from backend.app import app
  from backend.app import db
  
  ma = Marshmallow(app)
  
  class Measure(db.Model):
      __tablename__ = 'measurements'
      id = db.Column(db.Integer, primary_key=True)
      timestamp = db.Column(db.DateTime, auto_now_add=True)
      temperature = db.Column(db.Float)
  
      def __init__(self, timestamp, temperature):
          self.timestamp = timestamp
          self.temperature = temperature
  
  class MeasurementSchema(ma.Schema):
      class Meta:
          fields = ('id', 'timestamp', 'temperature')
  
  measure_schema = MeasurementSchema()
  measures_schema = MeasurementSchema(many=True)
  

      from sqlalchemy import create_engine
  
      server = 'localhost'
      database = 'TESTDB'
      driver = 'SQL Server Native Client 11.0'
      connection_string = f'mssql+pyodbc://@{server}/{database}?trusted_connection=yes&driver={driver}'
  
      app.config['SQLALCHEMY_DATABASE_URI'] = connection_string
      app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
  
      engine = create_engine(connection_string)
      connection = engine.connect()
  

• db.py

  from flask_marshmallow import Marshmallow
  from backend.app import app
  from backend.app import db
  
  ma = Marshmallow(app)
  
  class Measure(db.Model):
      __tablename__ = 'measurements'
      id = db.Column(db.Integer, primary_key=True)
      timestamp = db.Column(db.DateTime, auto_now_add=True)
      temperature = db.Column(db.Float)
  
      def __init__(self, timestamp, temperature):
          self.timestamp = timestamp
          self.temperature = temperature
  
  class MeasurementSchema(ma.Schema):
      class Meta:
          fields = ('id', 'timestamp', 'temperature')
  
  measure_schema = MeasurementSchema()
  measures_schema = MeasurementSchema(many=True)
  

      from sqlalchemy import create_engine
  
      server = 'localhost'
      database = 'TESTDB'
      driver = 'SQL Server Native Client 11.0'
      connection_string = f'mssql+pyodbc://@{server}/{database}?trusted_connection=yes&driver={driver}'
  
      app.config['SQLALCHEMY_DATABASE_URI'] = connection_string
      app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
  
      engine = create_engine(connection_string)
      connection = engine.connect()
  

所有文件都在后台文件夹中，如下图所示

from flask import Flask, Request, jsonify
from backend.Measure import Measure,MeasurementSchema,measure_schema,measures_schema
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)

db = SQLAlchemy(app)


@app.route('/api/measures')
def getAllMeasurements():
    results = Measure.query.all()
    return measures_schema.jsonify(results)

---

我丢失了什么？

如果要从同一文件夹导入文件，应该这样做

In Measure.py

from .app import app
from .app import db

在app.py中

from .Measure import Measure,MeasurementSchema,measure_schema,measures_schema

---

确保“后端”模块目录位于python路径

import sys中的目录中；打印（sys.path）

。要将文件夹添加到此路径，我需要做什么？您可以执行

sys.path.append（）

。最好是文件夹的相对路径（相对于调用模块）。文件“\app.py”，第2行，from.Measure import度量，MeasurementSchema，Measure\u schema，measures\u schema ImportError：尝试在没有已知父包的情况下进行相对导入