one-to-many

There is a nice explanation of 1-to-many relationships in datastore here by Rafe Kaplan. I tried to adapt that to a simpler case of User and Venue . So user can go to many restaurants; and I want to print the user email and the restaurants the user went to: class User(db.Model): userEmail = db.StringProperty() class Venue(db.Model): user = db.ReferenceProperty(User, collection_name="venues") venue = db.StringProperty() class OneToMany(webapp.RequestHandler): def get(self): scott = User(userEmail="scott@example.com") scott.put() Venue(user=scott, venue="club1").put() Venue(user=scott, venue=

Bacially Product has a one to many relationship to ProductPicture . My product picture model looks like this: picture_type_enums = ('main', 'related', 'option') class ProductPicture(Base): __tablename__ = 'product_pictures' picture_id = Column(Integer, primary_key = True) product_id = Column(Integer, ForeignKey('products.product_id')) picture_type = Column(Enum(*picture_type_enums)) url = Column(String(120)) and my product model looks like this: class Product(Base): __tablename__ = 'products' product_id = Column(Integer, primary_key=True) product_name = Column(String(100)) product_pictures =

I'm working on a Java project using JPA 2 + Hibernate 4.2.6 and I'm getting a strange behaviour. In my model I have two related entites: Question and Answer @Entity public class Question { // ... @OneToMany(mappedBy = "question", cascade = CascadeType.ALL, fetch = FetchType.EAGER) private Set<Answer> answers; // ... } @Entity public class Answer { // ... @ManyToOne(optional = false) @JoinColumn(name = "question_id", nullable = false) private Question question; // ... } This works perfectly: all Answer s related to a certain Question are loaded correctly. But now I need to change the tipe of

I am trying to understand the 1-to-many relationships in datastore; but I fail to understand how query and update the record of a user when the model includes ReferenceProperty . Say I have this model: class User(db.Model): userEmail = db.StringProperty() userScore = db.IntegerProperty(default=0) class Comment(db.Model): user = db.ReferenceProperty(User, collection_name="comments") comment = db.StringProperty() class Venue(db.Model): user = db.ReferenceProperty(User, collection_name="venues") venue = db.StringProperty() If I understand correctly, the same user, uniquely identified by userEmail

I have 2 tables. One is called Employee, and the other is called Phones, and an employee can have multiple Phones. Employee Class: @Entity @Table(name = "employee") public class Employee { @Id @Column(name = "id", unique = true, nullable = false) @GeneratedValue(strategy = javax.persistence.GenerationType.IDENTITY) private Integer id; @Column(name = "name", unique = true, nullable = false, length = 25) private String name; @OneToMany(mappedBy="owner", fetch= FetchType.EAGER, orphanRemoval=true, cascade={CascadeType.ALL}) private List<Phone> phones; Phone class: @Entity @Table(name = "phone")

I am trying to make a one-to-many relation in django. In my model I have a class Person and a class Group and the relation I want to make is that one Group can have N people inside, and a group cann't exist without at least one person inside In a MER diagram it would be like(imagine these are entities and relations) |group|1====<>-----N|person| As Arthur states, this is documented quite well in the Django documentation. It is in fact quite easy: from django.db import models class Person(models.Model): # Some other fields group = models.ForeignKey(Group, related_name='people') class Group