java - JPA 在运行时删除约束

Question

我正在从与同一实体(表示节点层次结构)具有一对多关系的表中删除实体。如果我将 xincoCoreNodeId 关系设置为级联，那么它就可以工作，但我不希望在实际应用程序中出现这种情况。

我不想移除叶子并移除其父代。有没有办法在运行时修改此关系或禁用约束，以便我可以删除整个表内容而不会收到约束提示？

    package com.bluecubs.xinco.core.server.persistence;

import com.bluecubs.xinco.core.server.AuditedEntityListener;
import com.bluecubs.xinco.core.server.XincoAuditedObject;
import java.io.Serializable;
import java.util.List;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.eclipse.persistence.annotations.PrivateOwned;

/**
 *
 * @author Javier A. Ortiz Bultrón <javier.ortiz.78@gmail.com>
 */
@Entity
@Table(name = "xinco_core_node")
@EntityListeners(AuditedEntityListener.class)
@NamedQueries({
    @NamedQuery(name = "XincoCoreNode.findAll", query = "SELECT x FROM XincoCoreNode x"),
    @NamedQuery(name = "XincoCoreNode.findById", query = "SELECT x FROM XincoCoreNode x WHERE x.id = :id"),
    @NamedQuery(name = "XincoCoreNode.findByDesignation", query = "SELECT x FROM XincoCoreNode x WHERE x.designation = :designation"),
    @NamedQuery(name = "XincoCoreNode.findByStatusNumber", query = "SELECT x FROM XincoCoreNode x WHERE x.statusNumber = :statusNumber")})
public class XincoCoreNode extends XincoAuditedObject implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @Column(name = "id", nullable = false)
    private Integer id;
    @Basic(optional = false)
    @Column(name = "designation", nullable = false, length = 255)
    private String designation;
    @Basic(optional = false)
    @Column(name = "status_number", nullable = false)
    private int statusNumber;
    @JoinColumn(name = "xinco_core_language_id", referencedColumnName = "id", nullable = false)
    @ManyToOne(optional = false, fetch = FetchType.LAZY)
    private XincoCoreLanguage xincoCoreLanguageId;
    @OneToMany(cascade = CascadeType.PERSIST, mappedBy = "xincoCoreNodeId", fetch = FetchType.LAZY)
    private List<XincoCoreNode> xincoCoreNodeList;
    @JoinColumn(name = "xinco_core_node_id", referencedColumnName = "id")
    @PrivateOwned
    @ManyToOne(fetch = FetchType.LAZY)
    private XincoCoreNode xincoCoreNodeId;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "xincoCoreNodeId", fetch = FetchType.LAZY)
    private List<XincoCoreAce> xincoCoreAceList;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "xincoCoreNodeId", fetch = FetchType.LAZY)
    private List<XincoCoreData> xincoCoreDataList;

    public XincoCoreNode() {
    }

    public XincoCoreNode(Integer id) {
        this.id = id;
    }

    public XincoCoreNode(Integer id, String designation, int statusNumber) {
        this.id = id;
        this.designation = designation;
        this.statusNumber = statusNumber;
    }

    public Integer getId() {
        return id;
    }

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

    public String getDesignation() {
        return designation;
    }

    public void setDesignation(String designation) {
        this.designation = designation;
    }

    public int getStatusNumber() {
        return statusNumber;
    }

    public void setStatusNumber(int statusNumber) {
        this.statusNumber = statusNumber;
    }

    public XincoCoreLanguage getXincoCoreLanguageId() {
        return xincoCoreLanguageId;
    }

    public void setXincoCoreLanguageId(XincoCoreLanguage xincoCoreLanguageId) {
        this.xincoCoreLanguageId = xincoCoreLanguageId;
    }

    public List<XincoCoreNode> getXincoCoreNodeList() {
        return xincoCoreNodeList;
    }

    public void setXincoCoreNodeList(List<XincoCoreNode> xincoCoreNodeList) {
        this.xincoCoreNodeList = xincoCoreNodeList;
    }

    public XincoCoreNode getXincoCoreNodeId() {
        return xincoCoreNodeId;
    }

    public void setXincoCoreNodeId(XincoCoreNode xincoCoreNodeId) {
        this.xincoCoreNodeId = xincoCoreNodeId;
    }

    public List<XincoCoreAce> getXincoCoreAceList() {
        return xincoCoreAceList;
    }

    public void setXincoCoreAceList(List<XincoCoreAce> xincoCoreAceList) {
        this.xincoCoreAceList = xincoCoreAceList;
    }

    public List<XincoCoreData> getXincoCoreDataList() {
        return xincoCoreDataList;
    }

    public void setXincoCoreDataList(List<XincoCoreData> xincoCoreDataList) {
        this.xincoCoreDataList = xincoCoreDataList;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof XincoCoreNode)) {
            return false;
        }
        XincoCoreNode other = (XincoCoreNode) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.bluecubs.xinco.core.server.persistence.XincoCoreNode[id=" + id + "]";
    }
}

Answer 1

如果您使用 Hibernate，则可以使用其对 batch processing 的支持有效地删除表中的许多行。基本上，查询从 HQL 转换为 SQL 并直接针对数据库运行。不过，这种方法也有局限性。例如，如果您持有对任何受影响对象的引用，则内存中的状态将不会更新。

不知道JPA本身是否支持批处理。可能不会。但是，如果您预计会影响大量行(数百行或数千行)，那么无论如何，这就是 ORM 并不是真正适合该工作的工具的情况之一。使用直接 SQL 或存储过程来执行此操作可能更有意义。无论哪种方式，您都可以隔离数据访问对象内的代码，以便高级业务逻辑不需要关心操作是如何实现的。