bidirectional-relation

问题 I have a problem saving entities with forms. The relationship that gives me problems is many-to-many bidirectional. Agent Entity /** * @var \Doctrine\Common\Collections\ArrayCollection $agentLists * * @ORM\ManyToMany(targetEntity="AgentList", inversedBy="agents") * @ORM\JoinTable(name="agent_agentlist", * joinColumns={@ORM\JoinColumn(name="agent_id", referencedColumnName="id")}, * inverseJoinColumns={@ORM\JoinColumn(name="agentlist_id", referencedColumnName="id")} * ) */ protected $agentLists

问题 I want to model the relationship between two entities, a group and an account with JPA/Hibernate. An account can have several groups, but not vice versa, so we have a OneToMany relationship between account and group. My working colleague suggested to model the entities Account and Group like public class Account { private List<Group> groups = new ArrayList<Group>(); public Account() {} public void setGroups(List<Group> usergroups) { this.groups = groups; } @OneToMany(mappedBy = "account")

问题 I want to model the relationship between two entities, a group and an account with JPA/Hibernate. An account can have several groups, but not vice versa, so we have a OneToMany relationship between account and group. My working colleague suggested to model the entities Account and Group like public class Account { private List<Group> groups = new ArrayList<Group>(); public Account() {} public void setGroups(List<Group> usergroups) { this.groups = groups; } @OneToMany(mappedBy = "account")

问题 Lets assume we have the following Entities: @Entity public class Department { @OneToMany(mappedBy="department") private List<Employee> employees; } @Entity public class Employee { @ManyToOne private Department department } It is understandable on an update that we need to maintain both sides of the relationship as follows: Employee emp = new Employee(); Department dep = new Department(); emp.setDepartment(dep); dep.getEmployees().add(emp); All good up till now. The question is should I apply

问题 I have an entity as below. I am curious if it is possible to create a relationship as I will be describing with the example: I am creating 2 Person entities Michael and Julia . I am adding Julia to Michael's friends set. After that I am retrieving Michael as a JSON response and Julia is available in the response. But when I am retrieving Julia, her friends set is empty. I want to create the bidirectional friendship relation by saving just one side of the friendship. I would like to get

问题 I have two class like this: public Class Company { public IList<Employee> Employees; } public Class Employee { public Company WorkPlace; } when I want to save an object of class Company: MongoDatabase Database = MongoServer.GetDatabase("db"); var workPlace = new Company(); var employee = new Employee { WorkPalce = workPlace} workPlace.Employees = new List<Employee>{ employee }; Database.GetCollection<Company>("company").Save(workPlace); StackOverFlow Exception will be thrown. 回答1: This is

问题 While trying to create a Bi-directional one-to-one mapping in NHibernate, I found that, I am unable to have the Reference of the objects recursively. For example: suppose I have one-to-one relationships between Person and Address . then after executing the following code, class Person { ... ... public Address Address { get;set; } } class Address { ... ... public Person Person {get;set;} } Repository<Person> rep = new Repository<Person>(); Person p = rep.Get<Person>(1); I need to have a non-

问题 I am trying to use Spring 3.x @ResponseBody to generate json/xml response, I am using JPA 2.0 ORM when there is many-many relation b/w tables then json is throwing LazyInitializationException If I give "eager fetch" then it is going into cyclic reference. 回答1: I recently encountered a similar problem: Jackson - serialization of entities with birectional relationships (avoiding cycles) So the solution is to upgrade to Jackson 2.0, and add to classes the following annotation: @JsonIdentityInfo

问题 Is there a way to create bidirectional relationship in Neo4j using Cypher? I would like the relationship to be bidirectional rather than making two unidirectional relationships in both directions For eg: (A)<-[FRIEND]->(B) Rather than: (A)-[FRIEND]->(B) (A)<-[FRIEND]-(B) Thanks in advance :) 回答1: No, there isn't. All relationships in neo4j have a direction, starting and ending at a given node. There are a small number of workarounds. Firstly, as you've suggested, we can either have two

问题 I have two classes as shown below in a bi-directional Many to Many relationship: Parent implements Serializable{ @ManytoMany(//declaration for join table) @JsonBackReference @com.fasterxml.jackson.annotation.JsonIgnore Set <Child> childSet; } Child implements Serializable{ @ManytoMany(//declaration for join table) @JsonManagedReference @com.fasterxml.jackson.annotation.JsonIgnore Set <Parent> parentSet; // other getter and setters } I make a call in my DAO to get a particular parent.