我正在使用SQLAlchemy和Flask为我的应用程序创建关系。我最近改写了关系,并且,无论我改变什么,我都会收到错误:
sqlalchemy.exc.NoForeignKeysError: Could not determine join condition between
parent/child tables on relationship CurriculumVersion.enrollments - there are
no foreign keys linking these tables. Ensure that referencing columns are
associated with a ForeignKey or ForeignKeyConstraint, or specify
a 'primaryjoin' expression.
在我的模特身上:
class User(db.Model, AuthUser):
id = db.Column(db.Integer, primary_key=True)
tf_login = db.Column(db.String(255), unique=True, nullable=False) # can assume is an email
password = db.Column(db.String(120), nullable=False)
salt = db.Column(db.String(80))
role = db.Column(db.String(80)) # for later when have different permission types
zoho_contactid = db.Column(db.String(20), unique=True, nullable=False)
created_asof = db.Column(db.DateTime, default=datetime.datetime.utcnow)
enrollments = db.relationship('Enrollment', backref='enrollment', lazy='dynamic')
firstname = db.Column(db.String(80))
lastname = db.Column(db.String(80))
def __repr__(self):
return '#%d tf_login: %s, First Name: %s Last Name: %s created_asof %s' % (self.id, self.tf_login, self.firstname, self.lastname, self.created_asof)
def __getstate__(self):
return {
'id': self.id,
'tf_login': self.tf_login,
'firstname': self.firstname,
'lastname': self.lastname,
'role': self.role,
'created_asof': self.created_asof,
}
@classmethod
def load_current_user(cls, apply_timeout=True):
data = get_current_user_data(apply_timeout)
if not data:
return None
return cls.query.filter(cls.email==data['email']).one()
return '#%d Course Name: %s, Course Version: %s, Closing Date: %s' %(self.id, self.course_name, self.course_version, self.closing_date)
class Enrollment(db.Model, AuthUser):
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
version_id = db.Column(db.Integer, db.ForeignKey('curriculumversion.id'))
cohort_id = db.Column(db.Integer, db.ForeignKey('cohort.id'))
def __repr__(self):
return '#%d User ID: %d Version ID: %d, Cohort ID: %d' %(self.id, self.user_id, self.version_id, self.cohort_id)
class Cohort(db.Model, AuthUser):
id = db.Column(db.Integer, primary_key=True)
days_to_completion = db.Column(db.String(20))
course_id = db.Column(db.Integer, db.ForeignKey('course.id'))
enrollments = db.relationship('Enrollment', backref='enrollment', lazy='dynamic')
def __repr__(self):
return '#%d Days To Completion: %s' %(self.id, self.days_to_completion)
class CurriculumVersion(db.Model, AuthUser):
id = db.Column(db.Integer, primary_key=True)
version_number = db.Column(db.String(6))
date_implemented = db.Column(db.DateTime)
course_id = db.Column(db.Integer, db.ForeignKey('course.id'))
enrollments = db.relationship('Enrollment', backref='enrollment', lazy='dynamic')
def __repr__(self):
return '#%d Version Number: %s, Date Implemented: %s' %(self.id, self.version_number, self.date_implemented)
class Course(db.Model, AuthUser):
id = db.Column(db.Integer, primary_key=True)
course_code = db.Column(db.String(20))
course_name = db.Column(db.String(50))
versions = db.relationship('CurriculumVersion', backref='version', lazy='dynamic')
cohorts = db.relationship('Cohort', backref='cohort', lazy='dynamic')
def __repr__(self):
return '#%d Course Code: %s, Course Name: %s' %(self.id, self.course_code, self.course_name)
任何帮助将不胜感激!
答案 0 :(得分:28)
此错误:
Could not determine join condition between parent/child tables on relationship CurriculumVersion.enrollments
表示SQLAlchemy无法在Enrollments
中找到合适的列以用作关系中的外键。
您定义了外键,但使用了不正确的表名。 Flask-SQLAlchemy在创建表时将CamelCase
类转换为camel_case
,因此您需要更改此内容:
class Enrollment(db.Model, AuthUser):
# ...
version_id = db.Column(db.Integer, db.ForeignKey('curriculumversion.id'))
#...
到此:
class Enrollment(db.Model, AuthUser):
# ...
version_id = db.Column(db.Integer, db.ForeignKey('curriculum_version.id'))
#...
或者,您可以使用__tablename__
属性覆盖Flask-SQLAlchemy使用的默认命名约定。
答案 1 :(得分:2)
尝试在CurriculumVersion类中使用primaryjoin,如下所示:
更改
enrollments = db.relationship('Enrollment', backref='enrollment', lazy='dynamic')
到
enrollments = db.relationship('Enrollment', backref='enrollment', lazy='dynamic', primaryjoin="Enrollment.version_id==CurriculumVersion.id")
注意:您可能还需要为其他类执行此操作。