[英]Hibernate hql/criteria result contains collection
I have two entities:我有两个实体:
public class Photo {
Long id;
String url;
@ManyToOne
@JoinColumn(name ="user_id")
User user;
// other fields and getters/setters
}
And second:第二:
public class User {
Long id;
@OneToMany(mappedBy = "user")
private Collection<Photo> photos;
// other fields and getters/setters
}
I am trying to get this DTO:我正在尝试获取此 DTO:
public class UserDTO {
Long id;
List<String> photosUrls;
}
But I can't find the right solution.但我找不到正确的解决方案。 I wrote next criteria - find user with photos by login:我写了下一个标准 - 通过登录找到有照片的用户:
getCurrentSession().createCriteria(User.class, "user")
.createAlias("user.photos", "photos")
.setProjection(getUserProjection())
.add(Restrictions.eq("user.login",login))
.setResultTransformer(Transformers.aliasToBean(UserDTO.class))
.list();
// projection
getUserProjection() {
return Projections.projectionList()
.add(Projections.property("user.id"), "id")
.add(Projections.property("photos"), "url");
}
Also tried with HQL:还尝试使用 HQL:
getCurrentSession()
.createQuery("select u.id, p.url " +
" from User u inner join u.photos p " +
" where u.login LIKE :login")
.setString("login", login)
.list();
But returned result is List<Object[]>
type but I need List<UserDTO>
.但返回的结果是List<Object[]>
类型,但我需要List<UserDTO>
。
Update:更新:
HTTP Status 500 - Request processing failed; HTTP 状态 500 - 请求处理失败; nested exception is org.springframework.orm.hibernate4.HibernateSystemException: IllegalArgumentException occurred while calling setter for property [com.memories.dto.UserDTO.photos(expected type = java.util.List)];嵌套异常是 org.springframework.orm.hibernate4.HibernateSystemException: IllegalArgumentException 在为属性 [com.memories.dto.UserDTO.photos(expected type = java.util.List)] 调用 setter 时发生; target = [com.memories.dto.UserDTO.photos@4e162869], property value = [ https://i1.sndcdn.com/artworks-000031744302-0730nk-t500x500.jpg] setter of com.memories.dto.UserDTO.photos;目标 = [com.memories.dto.UserDTO.photos@4e162869],属性值 = [ https://i1.sndcdn.com/artworks-000031744302-0730nk-t500x500.jpg] com.memories.dto.UserDTO 的设置者。相片; nested exception is IllegalArgumentException occurred while calling setter for property [com.memories.dto.UserDTO.photos] (expected type = java.util.List)];嵌套异常是 IllegalArgumentException 在为属性 [com.memories.dto.UserDTO.photos] 调用 setter 时发生(预期类型 = java.util.List)]; target = [com.memories.dto.UserDTO.photos@4e162869], property value = [ https://i1.sndcdn.com/artworks-000031744302-0730nk-t500x500.jpg]目标 = [com.memories.dto.UserDTO.photos@4e162869],属性值 = [ https://i1.sndcdn.com/artworks-000031744302-0730nk-t500x500.jpg]
I think with the above code all you have to do it is to assign the resultant directly to List and it should work like a breeze.我认为使用上面的代码,您所要做的就是将结果直接分配给 List,它应该可以轻松工作。 something like this.像这样的东西。
List<User> userList = yourCriteria.list();
So, i found not the best solution, but...所以,我发现不是最好的解决方案,但是......
Firstly, need to get list of entities User:首先,需要获取实体用户列表:
List<User> list = getCurrentSession()
.createQuery("from USer as u where u.login LIKE :login")
.setString("login", login)
.list();
Next, we declare in entity User method like this one, which convert List<Photo>
to List<String>
:接下来,我们像这样在实体 User 方法中声明,将List<Photo>
转换为List<String>
:
public List<String> getPhotosUrls() {
List<String> urls = new ArrayList<String>(photos.size());
for (Photo p : photos)
urls.add(p.getUrl()));
return urls;
}
And last step is hard-coded creating DTO beans:最后一步是硬编码创建 DTO bean:
List<UserDTO> users = new ArrayList<UserDTO>(list.size());
for (User u : list) {
users.add(new UserDTO(u.id, u.getPhotosUrls));
And, of course, you must have UserDTO(Long id, List<String> urls)
constructor.而且,当然,您必须具有UserDTO(Long id, List<String> urls)
构造函数。 If anybody will find better solution, pls write here :)如果有人会找到更好的解决方案,请在这里写:)
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