如何使用 Hibernate 转换平面结果集 [英] How to transform a flat result set using Hibernate

问题描述

是否可以将 SQL 的结果映射到非平面对象?

Is it possible to map result of SQL to not flat object?

List<Customer> customers = hibernateSession().createCriteria(CustomerDetailsView.class)
                .add(Restrictions.in("userName", userName))
                .setProjection(buildProjection())
                .setResultTransformer(Transformers.aliasToBean(Customer.class))
                .list();

就我而言，CustomerDetailsView 具有扁平结构.但我需要将它映射到这样的对象:

In my case CustomerDetailsView has flat structure. But I need to map it to object like this:

public class Customer {
    private String userName;
    private String title;
    private String firstName;
    private String lastName;
    private String type;
    private String companyName;
    private AddressDetails addressDetails;
}

和

public class AddressDetails {
    private String countryCode;
    private String addressLine1;
    private String zipOrPostCode;
    private String city;
    private String countryDivisionName;
    private String countryDivisionCode;
    private String countryDivisionTypeCode;
    private String residentialAddress;
}

推荐答案

是的，这是可能的.您可以使用自定义转换器:FluentHibernateResultTransformer.

Yes it is possible. You can use a custom transformer for it: FluentHibernateResultTransformer.

您可以复制粘贴代码，或者通过Maven添加jar:流畅的休眠核心.

You can copy paste code, or add the jar by Maven: fluent-hibernate-core.

您需要将 Criteria 与 Projections 结合使用.请不要忘记指定投影别名 (userName, addressDetails.countryCode)

You need to use Criteria with Projections. Please, don't forget to specify projection aliases (userName, addressDetails.countryCode)

Criteria criteria = session.createCriteria(Customer.class);
criteria.createAlias("addressDetails", "addressDetails", JoinType.LEFT_OUTER_JOIN);

criteria.setProjection(Projections.projectionList()
        .add(Projections.property("userName").as("userName"))
        .add(Projections.property("addressDetails.countryCode")
        .as("addressDetails.countryCode")));

List<Customer> customers = criteria.setResultTransformer(
        new FluentHibernateResultTransformer(Customer.class)).list();

与 HQL 一起使用

它不可能与 HQL 一起使用，因为 Hibernate 不允许在 HQL 中嵌套别名

It is impossible to use it with HQL, because of Hibernate doesn't allow nested aliases in HQL

选择 addressDetails.countryCode 作为 addressDetails.countryCode

addressDetails.countryCode 别名会出错.

使用原生 SQL

转换器可用于带有嵌套投影的本机 SQL(与 HQL 相对).在这种情况下需要使用别名和引号:

The transformer can be used for a native SQL with the nested projections (opposite HQL). It is need to use the aliases with the quotes in this case:

String sql = "select c.f_user_name as userName, d.f_country_code as "addressDetails.countryCode" "
        + "from customers c left outer join address_details d on c.fk_details = d.f_pid";

List<Customer> customers = session.createSQLQuery(sql)
        .setResultTransformer(new FluentHibernateResultTransformer(Customer.class))
        .list();

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