Question

我遇到了neo4j OGM库的问题，我按照库docs page上的说明实现了一个抽象的父实体，以包含我的实体的所有共享字段和功能。当我继承具体的类并尝试执行session.save时，我收到此错误消息MappingException: No identity field found for class: models.nodes.User。然后我尝试将id字段从父类拉到子具体类，并且保存操作成功 - 但是，父类的其他字段没有持久保存到DB中。我的结论是OGM出于某种原因忽略了父域。

这是我的父抽象类：

abstract public class MorpheusEntity {

    // Fields

    /**
     * The ID of the entity
     */
    @JsonProperty("id")
    @GraphId
    public Long id;

    /**
     * The date of first creation of the entity
     */
    @DateString
    private Date created;

    /**
     * The date of the last modification of the entity
     */
    @DateString
    private Date modified;

    // Constructors

    public MorpheusEntity() {
        this.created = new Date();
        this.modified = new Date();
    }

    // Methods

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || id == null || getClass() != o.getClass()) return false;
        MorpheusEntity entity = (MorpheusEntity) o;
        if (!id.equals(entity.id)) return false;
        return true;
    }

    @Override
    public int hashCode() {
        return (id == null) ? -1 : id.hashCode();
    }

    // Getters / Setters

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Date getCreated() {
        return created;
    }

    public void setCreated(Date created) {
        this.created = created;
    }

    public Date getModified() {
        return modified;
    }

    public void setModified(Date modified) {
        this.modified = modified;
    }

}

这是我具体的儿童班：

@NodeEntity
public class User extends MorpheusEntity {

    // Fields

    /**
     * Facebook ID of the user
     */
    private String facebookId;

    /**
     * First name of the user
     */
    private String firstName;

    /**
     * Last name of the user
     */
    private String lastName;

    /**
     * A URL address of the user avatar image
     */
    private String avatarURL;

    /**
     * A set of friends of the user
     */
    @Relationship(type = RelationshipNames.USER_FRIENDS, direction = Relationship.UNDIRECTED)
    private Set<User> friends;

    /**
     * A set of user connected devices
     */
    @Relationship(type = RelationshipNames.USER_DEVICES, direction = Relationship.OUTGOING)
    private Set<Device> devices;

    // Constructors

    // Methods

    // Getters / Setters

    public String getFacebookId() {
        return facebookId;
    }

    public void setFacebookId(String facebookId) {
        this.facebookId = facebookId;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getAvatarURL() {
        return avatarURL;
    }

    public void setAvatarURL(String avatarURL) {
        this.avatarURL = avatarURL;
    }

    public Set<User> getFriends() {
        return friends;
    }

    public void setFriends(Set<User> friends) {
        this.friends = friends;
    }

    public Set<Device> getDevices() {
        return devices;
    }

    public void setDevices(Set<Device> devices) {
        this.devices = devices;
    }

}

我已经尝试将父类放在映射包中，然后放出。＆lt;＆lt; - 编辑：这实际上是问题，父类没有被OGM映射

我错过了一些必需的注释吗？我的父类是否未正确映射？我正在使用来自Maven的使用SBT构建器的Neo4j OGM version 1.1.4的Play Framework 2.4。

感谢。

Answer 1

创建SessionFactory时，请检查您的抽象类包是否正在注册。

Answer 2

@NodeEntity应该在Parent类中，它将被继承到Child类。

请参阅文档中的Entity Type Representation部分

Neo4j OGM字段未继承

2 个答案: