python - Flask/SQLAlchemy Relationships -

so reading database relationships , seem puzzled this

below code of miguel grinberg in blog

from app import db  class user(db.model):     id = db.column(db.integer, primary_key=true)     nickname = db.column(db.string(64), index=true, unique=true)     email = db.column(db.string(120), index=true, unique=true)     posts = db.relationship('post', backref='author', lazy='dynamic')      def __repr__(self):         return '<user %r>' % (self.nickname)  class post(db.model):     id = db.column(db.integer, primary_key = true)     body = db.column(db.string(140))     timestamp = db.column(db.datetime)     user_id = db.column(db.integer, db.foreignkey('user.id'))      def __repr__(self):         return '<post %r>' % (self.body) 

correct me if understanding wrong

posts = db.relationship('post', backref='author', lazy='dynamic') 

the posts attribute having relationship post model posts attribute become? field? can contain? , backref mean? it's being defined author there no author attribute in neither models.

i looked docs , newb have it. still don't quite it.

so tl:dr

what posts become?

what backref do?

posts list can use abstraction in sqlalchemy access. sqlalchemy translate appropriate sql query when use (it indicates has-many relationship)

backref - hints sqlalchemy property in post indicate belongs specific user. in case mistake (look @ comments @ bottom of blog) , should user