我正在使用sqlAlchemy与Flask来创建我的应用程序的关系.我最近重写了关系,无论我改变了什么,我都不断得到错误：
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.
在我的车型上：
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),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,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,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',lazy='dynamic')
def __repr__(self):
return '#%d Days To Completion: %s' %(self.id,self.days_to_completion)
class CurriculumVersion(db.Model,primary_key=True)
version_number = db.Column(db.String(6))
date_implemented = db.Column(db.DateTime)
course_id = db.Column(db.Integer,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,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！
解决方法
这个错误：
Could not determine join condition between parent/child tables on relationship CurriculumVersion.enrollments
意味着sqlAlchemy在注册中找不到一个适当的列用作关系中的外键.
您定义了外键,但您使用了不正确的表名. Flask-sqlAlchemy在创建表时将CamelCase类转换为camel_case,因此需要更改此值：
class Enrollment(db.Model,AuthUser):
# ...
version_id = db.Column(db.Integer,db.ForeignKey('curriculumversion.id'))
#...
到这个：
class Enrollment(db.Model,db.ForeignKey('curriculum_version.id'))
#...
