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我正在尝试通过 ORM 将另外两个表添加到已经存在的 MySQL 数据库中。我要添加的表是DataInfo和Project，已经存在的表是User。如您所见，我的Project表有一个 ForeignKey 到User表，但是每当我运行代码时，我都会收到错误消息sqlalchemy.exc.ArgumentError: Mapper mapped class User->d_users could not assemble any primary key columns for mapped table 'd_users'。我在网上遵循了一些教程，但无法解决我的问题。

这是我的 models.py 文件。

from sqlalchemy import Column, ForeignKey, Integer, String, Date, MetaData, Table
from sqlalchemy.orm import relationship

from .database import Base

from datetime import datetime

class User(Base):
    __tablename__ = "d_users"


class DataInfo(Base):
    __tablename__ = "d_data_info"
    id = Column(Integer, primary_key=True, index=True)
    isURL = Column(Integer, index=True)
    dataSource = Column(String(100), index=True)
    dateCreated = Column(Date, index=True, default=datetime.date(datetime.now()))
    projectId = Column(Integer, ForeignKey("d_ml_projects.projectId"))

    data_for_project = relationship("Project", back_populates="data")


class Project(Base):
    __tablename__ = "d_ml_projects"

    projectId = Column(Integer, primary_key=True, index=True)
    projectTitle = Column(String(200), index=True)
    projectDescription = Column(String(550), index=True)
    problemType = Column(String(15), index=True)
    classLabel = Column(String(100), index=True)

    userId = Column(Integer, ForeignKey("d_users.id"))
    data = relationship("DataInfo", back_populates="data_for_project")

数据库.py：

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = "mysql+pymysql://martin:password@localhost/hope"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL
)

SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

我DESCRIBE d_users来自 MySQL；

+-------------------+--------------+------+-----+-------------------+-----------------------------+
| Field             | Type         | Null | Key | Default           | Extra                       |
+-------------------+--------------+------+-----+-------------------+-----------------------------+
| id                | varchar(36)  | NO   | PRI | NULL              |                             |
| oAuthId           | varchar(48)  | NO   | UNI | NULL              |                             |
| oAuthType         | varchar(20)  | YES  |     | NULL              |                             |
| firstName         | varchar(50)  | YES  |     | NULL              |                             |
| secondName        | varchar(50)  | YES  |     | NULL              |                             |
| city              | varchar(50)  | YES  |     | NULL              |                             |
| phone             | varchar(20)  | YES  |     | NULL              |                             |
| email             | varchar(100) | YES  | UNI | NULL              |                             |
| profileLink       | varchar(300) | YES  |     | NULL              |                             |
| profilePic        | varchar(300) | YES  |     | NULL              |                             |
| status            | varchar(10)  | YES  |     | NULL              |                             |
| notificationToken | text         | YES  |     | NULL              |                             |
| password          | varchar(64)  | YES  |     | NULL              |                             |
| confirmed         | tinyint(1)   | YES  |     | 0                 |                             |
| notes             | text         | YES  |     | NULL              |                             |
| created_timestamp | timestamp    | NO   |     | CURRENT_TIMESTAMP |                             |
| updated_timestamp | timestamp    | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------------------+--------------+------+-----+-------------------+-----------------------------+
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