如何进行休眠空间删除？

Question

我想删除我的数据库数据。

这是取自 TextBox 值的 AJAX 代码：

 function deleteVector()
{
    var value = $('#hs').val();
    console.log(value);
    $.ajax({
        type: "GET",
        url: "/deleteGeoJson",
        data: {id: value},
        contentType: 'application/x-www-form-urlencoded; charset=UTF-8',
        success: function (data) {
            var parser = new OpenLayers.Format.GeoJSON();
            var feature = parser.read(data.data);
        }
    });
}

这是我的按钮代码：

删除

这是我的控制器（get方法）

 SavegeojsonManager add = new SavegeojsonManager();

 @RequestMapping(value = "/deleteGeoJson", method = RequestMethod.GET)
@ResponseBody
public GeoJSON deleteGeoJson( final HttpServletRequest request,@RequestParam("id") final int vectorId) {
    return add.delete(vectorId);
}

这是 SavegeojsonManager 类代码：

 public GeoJSON delete(int id) {

    GeoJSON geoJson = new GeoJSON();
    try{
        EntityManager em = HibernateSpatialJPA.createEntityManager();
        em.getTransaction().begin();
        //How can I continue ?
       //If there's one thing if it is connected to the data you delete it
      //so cascade ??

    }
    catch (Exception ex)
    {
        ex.printStackTrace();
    }
    return geoJson;
}

}

这是 GeoJSON 类：

private int id;
 public int getId() { return id; }
public void setId(int id) {  this.id = id; }

Answer 1

首先，当您删除实体时，您不能在示例中返回该已删除实体的实例。

你可以这样做： 在您的视图中，例如在jsp 中，您可以显示通过Controller 发送的消息。可能在来自success 的ajax 请求中的一部分。

控制器代码：

@RequestMapping(value = "/deleteGeoJson", method = RequestMethod.GET)
@ResponseBody
public String deleteGeoJson( final HttpServletRequest request,@RequestParam("id") final int vectorId) {
    String message = null;
    boolean deleted = add.delete(vectorId);
    if(deleted){
        message = "Geo object has been deleted with id: "+vectorId;
    } else {
        message = "There was some problem with deleting GeoObject"
    }
    return message;
}

你的 dao 代码： 这可以通过多种方式完成：

 public boolean delete(int id) {
 boolean deleted = false;
 try{
    EntityManager em = HibernateSpatialJPA.createEntityManager();
    em.getTransaction().begin();
    Query query = em.createQuery("delete SavegeojsonEntity s where s.id = :id");
    query.setParameter("id", id);

    int result = query.executeUpdate();
    em.getTransaction().commit();
    if(result > 0){
        deleted = true;
    }

 } catch (Exception ex){
    ex.printStackTrace();
 }
return deleted;
}